Hyperledger Foundation Meetups, 2 Nov 2020

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From YouTube: Blockchain Techfest 2020 - Part 1

Description

A virtual meetup hosted by the Hyperledger India Chapter. Listen to Senthilnathan Natarajan speaking about Private Data Collections in Hyperledger Fabric. Hear from Michael Holdmann on how to get faster throughput in Hyperledger Fabric. Learn to write smart contracts in Hyperledger Sawtooth from S Gopinath, Sr Scientist, NIC. Understand the foundational concepts behind remote attestation in Hyperledger Avalon from Muhammad Usama Sardar.

More about the event is at: https://www.meetup.com/Hyperledger-Bangalore/events/274096080/

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Hyperledger – Open Source Blockchain Technologies

Hyperledger is an open source community focused on developing a suite of stable frameworks, tools and libraries for enterprise-grade blockchain deployments.
It serves as a neutral home for various distributed ledger frameworks including Hyperledger Besu, Fabric, Sawtooth, Indy, as well as tools like Hyperledger Avalon, Cactus and libraries like Hyperledger Aries, Ursa. Learn more about Hyperledger projects: https://www.hyperledger.org/use

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#Hyperledger #HyperledgerMeetups #Blockchain

A

So I think, let's get started then I'll.

B

Start then try all right good morning, everyone and welcome to this inaugural hyperledger techvest event, uh I'm julian gordon, uh I'm the vp for asia, pacific for hyperledger and I'm speaking from sunny hong kong today and I'm delighted to be invited to open this event.

B

Firstly, I'd like to thank the hyperledger india chapter african chapter and the apac meetups for organizing the series. This is really a great show of collaboration. I think one of the first we've done across multiple different chapters, so great great collaboration.

B

So what is the hyperledger techfest? As I said in one of the linkedin messages? Promoting this event? One of the questions I always get and many people in the community get asked is how does one here get to hear and meet the contributors and maintainers of hyperledger projects?

B

Well, this is one of these events today you'll hear and see four contributors or maintainers of hyperledger projects and those these are the people that write the code and without them, hyperledger hyperledger is all about writing. Code uh hyperledger would not exist.

B

um This is the first of three events and you'll hear from many other contributors over the coming weeks. It's such a great idea. uh There is so much great knowledge and experience to be shared from these uh contributors and maintainers, and I'm looking forward myself to listening and interacting today and please do interact, ask questions. We have a q, a channel. We have a chat channel. Please do ask questions. We want to make this.

B

You know interactive as well, so why uh the name techfest well arun, who you're going to be hearing from soon who created this event, was keen to have it during the festival season season here in india. So he came up with the term tech fest, so please do enjoy and to celebrate this festival season on this hyperledger tech fest.

B

By the way, if you don't know arun, he is the co-lead of the indian chapter and also this month got voted to the global hyperledger technical steering committee. So congratulations, arun on that. The technical steering committee or the tsc as commonly known, uh is called the heart and soul of the hyperledger project, and it is made up of contributors like some of the contributors who have who are here today, who are elected once a year and they're elected by the contributors of the project. It's what we call a democracy.

B

Those who get involved are those that run the projects and you can listen to that to the technical steering committee, and actually, you can listen to any of the different projects, uh their meetings uh and it's a great way uh to get the feel and pulse of hyperledger. So I really uh recommend listening to the technical steering committee uh calls.

B

The second question I often get asked is how how do I compute? How does one contribute uh to hyperledger? I would encourage everyone listening. You know honest call on this webinar today to get involved in the hyperledger community contribution can come in many different forms.

B

You can contribute to projects and you're going to be hearing about a number of projects today, and these these projects are always eager to get more uh contributors. uh You can cont. You can help organize events like this. You can help run the chapter. I talked to run before and he's looking for for more and more people to help here, specifically in the indian chapter, but all other chapters are looking for people. We need help with translation. We've done, I think, like fabric.

B

We have now nearly nine different languages, and some of that is done here uh in a lot in india, we have malayam, we have chinese, we have spanish, we have many many languages, but we're always trying to make uh you know what we do here at hyperledger, more accessible. So translation is something we're very keen on writing documentation.

B

It's you know very much a requirement and obviously people who want to use technology. You know the better the documentation, the more accessible it is so basically any activity that helps build our support, our shared ecosystem with a hyperledger, so please do contribute. A great way to start is actually to join, and I discussed this with the room just before right, the hyperledger, india chapter course they happen every thursday afternoon.

B

You can find out that the times and the and the call-in numbers on the hyperledger wiki, so that's wiki.hyperledger.org and then drop down in groups and you'll, see the ledger, uh india, and actually maybe we can put that link uh in in the chat today. So so please do or not, just in your chat anymore, just reach out to any of us any of these contributors.

B

Anyone involved in hyperledger, everyone is very, very open to helping people come and help contribute uh to this ecosystem to hyperledger, so that just a quick few words I first uh I'd like to say thank you for all attending um stay safe and enjoy this event. Okay, over to your roon. Thank you.

A

Thank you julian. That was a great introduction and yes, we welcome all sorts of contributions from india and even if you are developer or program managers or project maintenance, then please do feel free to join the weekly calls. I just shared the link on chat for all of your reference, and you will also find this public information and hyperledger's public calendars events and to start with today's event.

A

We welcome you again warmly and we will be starting with mr gopinath, who is a senior scientist at nic government of india, and then he will be speaking about how to write a transaction processor, how to write a smart contract in hyperledger sawtooth, and we will now switch over to mr.

A

C

Thank you arun. uh Can I just uh do my presentation yeah? Yes,.

C

So, as aaron told I work at some senior scientist in national informatics center government of india, it is a technology home for government of india, so I work in a network division where we run a countrywide national knowledge network.

C

So that is something like internet2 in america, so some similar kind of network we have in fact we appear with internet too also. So basically, I am in that area, but I mean in my group we are all around us, so we work with software. We work with that people and we share knowledge everything and make it so I have been doing system administration also quite some time back and no knows about the importance of the various uh the verticals in ict, especially in government as a scenario.

C

So apart from working, so I I'm doing my higher education, so I am doing my masters, so in my master's I have to do a project work. The final semester is all about the project work. So in fact you can see the logo here in my presentation. It is not of nic. I put the logo of my institute bsa crescent institute of science and technology, so the project, so I am interested I have always been wondering see because the logs are very important for me.

C

Whenever the router exchanges, the route information it has to be logged whenever somebody logs in my email system, there is a log when the mail goes from x to z, there must be a log and the law enforcing agencies may ask for a log. The log is a very critical thing, a very important thing for various reasons.

C

So how to make that immutable? I mean how to secure the logs. How can I prevent anyone can have in support? I can I mean I'm basically an unix guy, so I know uh log into root and then go to that. Where locks is, uh then you open any log file and delete some file? I mean it is very easy to tamper it so how to make that uh this thing?

C

Why not, I use blockchain for that part, so the complete investigation on on this aspect and made me to do a project in this particular area. So my project title is trustable logs using blockchain- I'm not the first person to invent these things, but this idea is natural to me because I'm in that field making it I'm one minute.

C

So the problem statement is something like this: events are recorded as logs locks are used for various purposes. Regulatory authorities requires that most of the legacy travel systems are temperable.

C

I can use warm device if I want to make a reasonably a trustable thing, but it is very costly and I can't do that in every each and every case. Is there any solution using software like blockchain? Yes, because the other name for blockchain is basically immutability.

C

These are the two phases I have done. The phase. One is basically a steady thing and phase. Two is an implementation thing, so the next thing is, since it is an academic project, there is always an intention that I should learn something new, so the rust is a beautiful language. I am told so I wanted to learn rust when I wanted to learn rust and do this part then I have been searching which blockchain platform supports rust as an sdk, then naturally the sawtooth also comes.

C

I never even thought what are the complications or how easy it is or out of it is for the sawtooth. I just selected that part assuming that at some point of the time I'm going to get succeed in that part and people are going to help me in that part.

C

So I become a member in hyperledger group and I've been exchanging the messages I've been reading the documentation. Then I get to know the weekly meetings are happening and that I got the contact of her own, etc and then the things grown.

C

So my implementation is a very simple one. It's a four node blockchain cluster and I use aws because anywhere I can go there. I can just access that part and.

C

And these are the literatures I require to refer. um There are already lot of literature on how to build a trustable blockchain, for example, the first prop the paper tried to implement using exonum.

C

So again it is a pbft system, so other people also making it and the one beautiful paper is vitalik buterin's white paper, which I really learned something about. I'm trying to learn something about the blockchain and another beautiful the paper, uh the introduction to sawtooth pbft in the blog, a wonderful, beautiful, plain, english, simple, english and beautifully explained it. So these are the literatures I referred uh during my project.

C

So what is the architecture of my thing? Let me understand, I mean put it like this, so I have four blockchain nodes and the logs are basically generated by the systems, the various systems. It could be an email system, it could be a router or it could be a banking transaction or any for any system. For that matter. There is something called log sources.

C

Then I have a build. What is called a log network.

C

I I I built a log network. What I do is I send the logs to all the blockchain nodes.

D

C

Real time in real time or, for example, if the log is generated immediately, that is sent to all the blockchain nodes so that the blockchain nodes knows that this event is really happened. It is in real time it is all sending it. Then I am going to separate blockchain network pbft network. I have all the four nodes are there and I have a pbft network is a separate, separate network. Logically, it is a separate it can be residing in the same ip subnet, but logically I mean for an understanding purpose.

C

I keep it a separate one. So like this, so what happens? It is all getting accumulated, then the owner of the lock source he generates a transaction. For example.

C

Let us take foreign instance, I'm trying to record the mail log, so let the file name me slash where slash log slash mail log. So whenever there is a mail whenever there is an even happening, the logs are emitted on.

C

These logs are all transported in real time to the blockchain nodes and then, after some time at the end of the day or whatever it is, then the owner of the mail, the the person who is in charge of that particular resource mail, log log, so that person generates a transactions and then he files to one of the nodes. Then the pbft network takes care of everything and then it the transaction. I mean because all the nodes I mean the transaction processor is able to access the logs which are generated already.

C

Then it can compare whether I am telling the this. The transaction which I am generating at this point of time, is correct or wrong. Then, if it is so, then it is pushed on to the blockchain and it grows like that.

C

So this is the whole setup I have so later. At some point of time an auditor comes up and he wants to verify the mail logs and all then you ask the owner of the law. Give me your transaction, I mean give me your log file, so he takes the log file. Then he uses the same kind of structure and he queries the blockchain node. So this is the law from byte I mean start byte is zero n byte is say 1024.

C

What is the hash of that part? If that hash matches the blockchain hash, then that particular thing is said to be not tampered with that then it queries for what is the I mean from 10 25 byte to 20 47 byte. So what is the thing so like that? You can query and that part, and then you can verify on each block each block of the log. He can just verify and if he's satisfied, that's fine. He goes forward that part.

C

So here I can have something called a partial trust, establishment suppose if the mail log or the speed log or webrobic proxy log generates in a few tons of uh megabytes, so if tampering has been done at only one, not one particular point, I don't need to throw the entire thing I can just I mean it is basically the it is a by boundary system so, which are the things are all is intact. That alone I can take it back, and then I can do that part. So here after the logs are all generated.

C

What I can do is the blockchain nodes need not store uh the real logs, the only the hashes can be stored, so you can the purge the the other stuff. I mean the original lock stuff, so you can store only the hashes, so there is no the space constraint. Also in this part, so I got to the client, module and transaction processor module and verification module.

C

So the client, on behalf of lock source, as I told the lock stream, is there the transaction batches and then it sends the sawtooth validator.

C

The transaction processor business logic runs in every node and transaction process semantic just a minute. I think I'm uh chosen the wrong powerpoint just in just a minute.

C

So what exactly I'm storing about the lock- and this is my payload- so I have I mean I have this- is the payload. I store some id, for example, if it is a main log of this particular thing I give some id, it is a basically a 32-bit integer, some id is there. Then I take the start, byte and n-byte.

C

So I got two implementation, so in one implementation let us take that the second implementation- it is a 64-bit start by turned in byte, and what is the data size, data, hash value sha-256 so on? This payload is c bar serializer using c bar.

C

So what is the programming model of a sawtooth? So sawtooth? We got what is something called validator, that is a blockchain node and within the validator system. The transaction processor is running. This transaction processor is the application specific, which means that every application developer should implement this transaction processor, so the transaction processor I mean it basically validates transaction semantics and all business logics are applied over there and that in the validator, the blockchain node the validator contains what is called the global state.

C

So the clients, the person or I mean- or the systems who are going to submit the transactions through rest api. They are going to get contact, the validator, submit it and suppose they want to retrieve some kind of state they can retrieve that part. So this is thick. I mean uh 40 000 feet uh the eye view of what is the I mean.

C

This is all about the sawtooth at a very high level.

C

So inside the blog I mean the sawtooth, the validator we have something called. There is a block. This is a basically diagram. These are the transaction processor and this transaction processor is. We have to write it and we have to place it. This is basically the core of the validator, so it contains a global state. It contains blocks, uh it contains consensus engine proxy, which means the consensus engine is pluggable. For example, in my case it is pbft and there is a block.

C

Amoled transfer, tp handler transaction processor, handler everything is there and this the network part which makes the full mesh connectivity with other nodes.

C

So what I do is uh uh I read the file blocks. Suppose uh I'm given the log stream for me, the it is a basically log is a stream of bytes so which means it could be that I don't know say that the law it should be in with the crlf or something like that, so it could be even a binary file. It could be even a binary log.

C

So for me the logs are, the events are recorded in a stream of buys zero to byte uh starts from a byte a to start with the that is a log. So I read the stream and I generate the payload. How do I generate the payload I take? uh I give the id for the particular string. Take the start by invite calculate hash. That is my payload, and I then I do. I just push the payload.

C

So after certain count, I generate into a transaction set of transaction and set of transactions are then pushed to the batch and then finally, I push it to the call the rest api and submit to the one of the nodes.

C

So this is another thing I have payload and I got the various serialization uh this thing, so the payload is represented by the either c bar c bar or protobuf or csv, whatever format then the transaction letter generation. I will do for that. I need a key, so the transaction I create, then the batch header I have to create then push the transaction into batches. Then I make a submission, so this figure is something that the entire thing that the whole chain I put it, but it is not really visible.

C

I could not able to make that making it, because I I was, I mean I thought that I could do some better presentation, but last three days for four days uh completely separate from here, so I could not able to even enlarge or make it. I did not even touch that.

C

What is a transaction processor modules, it is runs in every saw tooth node suppose I write an application in a sawtooth application, all the business logic I put it in a transaction processor, so this transaction processor, I need to run in all the blockchain nodes.

C

Suppose I have the four node in all the four nodes I have to run the same transaction processor module multiple transaction processor can run at the same time. A blockchain node can contain can support various application at the same time and multiple transaction I can run at the same time and it uses a git set methods to set the state with the payload and to read the state. I can use the gate method and the negative, so the transaction processor module asked to implement an apply method.

C

That is something called an apply method which the validator calls. So what happens is whenever a validator node receives a transaction from any client and depending upon its family name, family version, it selects, I mean which transaction processor it belongs to and.

E

C

It calls that particular apply method and then the business logic runs in that part depending upon the business outcome, either your transaction, whatever we write that transaction processor set the the state or get the state. So this is the basic overall idea of what is the transaction processor module, so the same is depicted over here. This is the transaction processor which I have here and first, whenever a transaction processor, when I started on the first thing, is, I have to say hello to validator. I have to do something called registration.

C

I have to tell I am the transaction processor, so I am listening on this particular family name and family version. It is something like opening a tcp socket something like that. So I am reasoning on that particular part. So the validator node knows that part. So whenever it receives a transaction of that particular part and after uh doing some kind of a syntax validation- and it is okay, then it just calls the particular apply method over that part and then make it out.

C

So, basically, you have an apply method: the validator send tp process request and the trade object. uh The transaction contest. These are masked as a parameter to the apply method so that, when the apply method returns- and it can take all these things- basically, the transactions are sent over here. So accordingly, it can do this processing and then it can get us in the method. So the transaction say it depends upon. I have to set the family name, family version and what is the namespace, etc.

C

C

So this is what I got it basically, so I mean.

C

The various verification, a lot of print line statements, a lot of things- are there so because of my conditions right now, I stop here. So kindly excuse me for my poor presentation today because of my situation so probably next time. I think I hope to do the better stuff. I stop here. Thank.

A

You thank you. We have couple of questions if you don't mind answering them. So the yeah first question is: where are the locks actually stored.

C

The locks are uh initially, the locks are also stored in the blockchain nodes when it is get transaction is when the when I fire the transaction of that particular thing, and then it gets into recording the block. Then the logs are not necessary to be stored in the uh blockchain node, but I can always the the the logs owner need to store it in some safe storages to produce the auditor at later point of time.

C

But the transaction processor requires, because how the transaction processor requires to know what is really the log, then only they can come into consensus and then they can record the hash. So for that only initially they require the log at real time, store it temporarily for some time and moment the transactions are over, then I can throw off those logs in the blockchain node.

A

Thank you and one more question, so how long did it take for you to build the such a system, including testing, etc?.

C

No, I started somewhere in uh I mean february uh feb uh last week, where I started interacting and all so initially I mean I suffered a lot. It suffered a lot in the sense that reading documentation. The rest itself is a challenge for me, because russia, I want to do in really interest.

C

So I have chosen that part and really the things are not bent on well. So if uh arun can't remember uh one thing that in one night I just wrote to around somewhere in the first week of march or second week of march, that I want to switch over to python and really submit, then he sent some sample files.

C

So just few insight on that, but I got a clue in that part. Then I started writing. So I think practically, if you take the first week of march or second week of march, is really starter and initially I just completed in april itself. I completed it. So uh thing is that I started using like a bitcoin style because any blockchain uh any person who want to read about blockchain uh the thing is that uh naturally one another one will follow about the bitcoin, the bitcoin everything there in the blocks. There is no something called.

C

There is no emphasis on states, there is no addressable states and all so I started doing right. In fact, I started storing everything in this. uh You know in one particular state, then for verification I started digging the blocks and then taking out it in one dan milton video. I saw that one. He specifically told no. No, this is not at all in video. He told that this is not a blockchain. You have to use states, then my god, then I have to rewrite my program.

C

Then I went to the second style of programming, then that took about because there is no much of it. Only thing is. I have to manipulate the addresses so for some reading material is required. So then that took about 15 days or so not another time. I think at three months time, maximum three months time I believe, but the polishing and fine tuning it takes a lot of time. That's I'm not counting it, but the core stuff.

C

I think, two hundred of months to three months, I think I did and thanks to aaron he answered a lot of questions through email. I can't support it.

A

Thank you, sir.

A

um Thank you again so we'll move on to our next presentation next topic for today is about how do we? How do we scale up our fabric network? How do we make it like 10, 1000 times much faster and to speak about this kind of to answer these kind of questions? We have a team joining us from united states, and I would like to welcome mike- and this thing harry michael, um so michael is the ceo of prasaga and I would hand over to michael for further session.

F

uh Good morning, everybody and thank you very much for uh inviting us and allowing us to participate in here. So is my screen being shared. There's always first question.

F

Yes, okay and we'll just go to slideshow all right uh again, thank you and yes, we do have uh uh the team on. So let me make a quick introduction. uh My name is michael holdman, I'm founder and ceo of prosaga prasaga is a blockchain technology company. We are.

F

Have designed and are building uh an open, permissionless trustless chain with a a on a token uh based entity um and uh through the process of doing some things we uh we have run into uh some understanding or enlightenment, about blockchain scaling issues and such and that's what we're going to talk about here, specifically one of the uh technologies that have come out of our research and and design phases.

F

So um in our in the process of of looking at how to scale a blockchain.

F

One of the things that came into uh account was the fact that we couldn't see a way to truly scale because of the inability to to actually move state uh from uh pair between parallel chains from char to chard when they started to come up with the sharding technology and the things that we found here and it's a challenge, as we say in chain code, but the same in smart contracts, um they're static, they're, not dynamic, versioning or updating chain, smart contracts or chain code is difficult.

F

We compare it to a smart contract to say every time you want to write a word document. You have to write the word application. You basically have to copy a smart contract paste it into an editor edit it and then upload it. So you're re-uploading the program every single time, they're not easily, created or updated it can take depending on the complexity. Yes, you can do a simple smart contract in order to do a transfer of a token from one wallet to another.

F

um However, it's uh when you're starting to get into complex supply chain and such like that it is not as easily done it can take multiple fte years to create and deploy code. Reque requires reloading for each new contract and it doesn't have a global repository.

F

So what we have uh is the extensible blockchain object model. Now a little history about extensible blockchain object model. um It is uh we call it a decentralized global operating system and the the first time we've uh integrated it with a blockchain is on hyperledger, um we'll go back to the uh where it started from, and that was uh it's. It's based on a messing message, passing architecture which was developed by xerox labs uh the park. That's a palo alto research, uh research and um it was the the message passing architect.

F

Architecture called small talk was introduced in the early 70s. um Since then it's been used as an underlying architecture for the leading global operating systems. uh You might remember- um and we compare a lot uh smart contracts to an ms-dos ms-dos, where you can run uh one application at a time and then the invent or the introduction of windows and windows is a common object model. A class tree. uh It's a it's. A modified version of the first class object model.

F

First class object model was actually uh also utilized by ibm in a system, object model and another organization called gold corporation in their uh uh pen, point os, which was a tablet based operating system.

F

uh The other uh organization that uses the a first class object model for the modification modified first class object model would be mac os 10.. It was used by steve jobs when he had next and started next os. So history on on you know what uh first class object model is. Is there dave? Bieberman will go further into this, um I'm kind of going to do the highlights and then dave is going to go into he's this.

F

The co-founder and cto he's going to go deeper into the actual tech he's going to show what uh how classes and objects work within hyperledger and also do a a brief um code review or loading that show how it loads into hyperledger and what it is is basically an object-oriented blockchain.

F

Now we did have one individual casey tam, who is a hyper ledger instructor? He was gracious enough to uh do it, take time to do a review of the uh development environment and uh test net that we have set up and available. Now it is mvp.

F

This is not production ready yet, but it does allow you to go in and start to use object model use the x-bomb and test it out on hyperledger the interesting thing that this does- and I I highlighted it theoretically, the developer does not care about the blockchain as it is well handled by the infrastructure so to go into here. The advantages of having an extensible blockchain object model makes go to market 10x, faster, 100x faster.

F

The reason is because everybody is referencing, the same exact class or copy of code you're, not rewriting code and each time and uploading it into the contracts.

F

It's it's fully dynamic, you're, instantiating or referencing code from a class tree into your account. It's real time updates. There's no service interruptions. If somebody sends you a transaction and you do not have the proper code in order to execute that transaction or whichever part of that transaction you're supposed to, then your account will look up. The class tree find the in the the code, that's necessary for you to execute that transaction, and if you have all the proper credentials, it will instantiate it into your account on hyperledger.

F

It creates a repository of reusable code throughout all nodes and it makes many-to-many relationships feasible on each on a single chain and what we mean by this in supply chain. uh We we find that the issue is not when you're at the say, general motors at the top of the chain, but it's when you're the bolt the bolt manufacturer down at the in lower in the tree in your supply train tree and what that's going to uh what x-bomb allows you to do.

F

Is it doesn't care if it's an ibm, blockchain platform, oracle, blockchain platform, sap or any others if you're on aws the xbomb just knows that you're a hyperledger fabric blockchain, and so it will integrate or implement uh with that.

F

So what we have developed is a blockchain application framework on the business side. What this looks at is everything from layer, uh three, four five and six layer. Five in this instance is hyper. Ledger um is unknown or not. Does not have to be uh managed at all by the application developer. The application developer always plays up in layer two and the applications are just the applications where the user interface will, uh or with the user user interfaces with the blockchain applications can cover. You know whether it be pharmaceuticals, oil and gas aviation.

F

uh The list goes on, so what dave is going to do, and I'm going to turn him over here in a few in a minute or two is he's going to go deeper into how we're actually integrated into x-bomb and go into the how we're integrating into the pure nodes one of the things that we had to make sure when we did when we developed this is that um we don't do any changes to the hyperledger source or any of the other sources that's utilized in order to make a successful hyperledger uh fabric network and the other thing that dave will do is go through and show you exactly how code loads dynamically again, you don't have to add more chain code, you don't ever have to add new channels, you can dynamically add new classes to a class tree and whenever those classes are necessary or the code within the those class objects are necessary, the chain, your account automatically uh instantiates a you know that class object into your account.

F

So I will go ahead and stop sharing. I will let dave carry on if anybody has any questions on this part of it. Please do ask, I will be back to talk about uh the finish up. uh The last part after dave is done.

G

Good morning share screen, listen share and okay good morning. Can everybody see my screen? I assume yes, so um a couple quick things about the uh extensible blockchain object model. Another way to think about this is um instead of object-oriented programming, an object-oriented blockchain, the uh I'll go into what um why? How we do that, but the core piece to recognize is that for any object in any object-oriented environment, it needs a reference to it.

G

In a programming environment, you have essentially a pointer managed by the programming runtime environment, whether it's everything from c plus plus to java to c sharp to python, to you name the language actually even goaling, even though it doesn't do inheritance does the same thing.

G

What we recognized is that a interesting part of the blockchain is because it's immutable, you can have completely unique um references, object, references stored on the blockchain and we take advantage of that. You'll see how that makes it's called a first class object model and uh first class object models. Go all the way back to small talk and before that small talk uh being the language in the designer the author of it, who invented the term object-oriented programming and we're basing that all the way back in that technology, which is all message passing with.

G

What's called late, dynamic, binding or very late dynamic, binding first, a little bit about how we put it onto the hyperledger fabric. um Technically, we probably could put this on hyperledger sawtooth as well. Although we started down the path and fabric first and we're focused on uh getting a proof of concept out, I'm on the left you'll see a traditional.

G

um I use the word traditional, because that's how hyperledger fabric works, I don't mean that it's a negative thing is that this is how how it actually works. You uh launch the blockchain.

G

We actually use the test network from the fabric, samples and you'll see that later and then you load chain code code a little redundant but and then you run on it in the transactions are sent to the train code and the chain code interacts with the database in the state database layer in the blockchain consensus layer manage that in our environment we don't change any of the hyperledger fabric code to make this work.

G

The difference is that for us, the chain code, layer, loads, the class, major infrastructure that enables the class manager, environment or classes and objects, above that you dynamically load class code um into your runtime environment. We actually use what's called the external chain code model for hyperledger fabric, as opposed to having the hyperledger fabric, build the source in a docker. For you, you it's a part of version 2.0 and beyond.

G

um On top of that, we have class application framework in um ordinary objects and accounts walk through them very quickly. Similarly, so in the standard environment, the first part, your hyperledger fabric, is managed by peer nodes and orders. um What you'll see is a test network. We actually just use the simple one. It runs two nodes in one order, the order I'm going to believe it's currently doing raft. I don't remember how it's configured but it's transparent to us.

G

The chain code layer, you use literally load as a pure, using a we're using all command line from the pure node command at the moment, but obviously you can send strings as well from an api.

G

The peer node loads, a chain code. As a for an external chain code, you actually send out a tar, zip file, that's configured appropriately. You can read that in the online tutorial for hyperledger fabric, we a very important point. I think we skipped so far- and this just reminded me our current implementation.

G

All of the classes are written in the go programming, language and they're loaded as shared objects, which are known as goal goaling, plugins and there's a specific command to enable doing that with go. uh What's very important here is we're not actually at runtime um we're not actually compiling the code. You're literally loading a pre-compiled code so and it only needs to be load once per node when it runs a transaction. Once a class is loaded, um it gets, it can stay in the environment, so you don't really have an overhead for loading.

G

It glass application framework. I will show you the foundation classes and we have a diagram of it and we will just do a very quick command line load to show that we actually call them the bootstrap classes and once they're loaded you have, the ability to create accounts accounts can contain ordinary objects. It's similar, an account, is an object instance.

G

Every account has one root: object, called the account object and then everything else is considered containment underneath it. So you have a containment tree for each account. We use that model um superimposed on top of this environment. um That's part of the uh bootstrap classes.

G

It is actually possible to think of other models, but in the blockchain world accounts are the common um construct for everybody a little bit about what a first class object model means, because it's relevant very, very relevant for how we made this work in a first class object model. Everything are actual objects. They exist at runtime. This means that the class that creates the object so here's class object, which creates ordinary objects in a meta class. Excuse me, a meta class object makes classes which make objects.

G

You have a reference to each one of these, because the blockchain is completely immutable. It's now, rather rather trivial to make global references to every single object, whether it's a meta class, a class or an object and, of course, everybody's inheritable. So you can inherit from a meta class or a class. You can't inherit from an ordinary object.

G

This is a key thing, because it means that once you've established any object or any class or any meta class, that reference is usable anywhere at any time bar with with respect to any sort of scoping rules like if you're not allowed to send a message for into somebody else's account. That's a thing, but as far as the reference itself is concerned, it's just another object. Reference.

G

The basic structure once you've loaded the class major infrastructure loads, the root class object. So everything this is a single inheritance, not a multiple inheritance, although it could be done with multiple inheritance, so single inheritance with the ability to create interfaces.

G

The root inherited. The root object is called class object. The class class is the root metaclass in class. Dictionary maintains a string mapping between uh names in what we call ledger, object, ids. What I mean by that is we create, like I just said the uh like. I just pointed out here the uh independent object ids, which we actually do a chain hash to create using the standard uh shc256 algorithm in the um in order to map back and forth.

G

We call those ledger object, ids, so you can actually work from strings as you'll see further on there. We return the 256 hash as a string of integer numbers.

G

This is what the bootstrap classes look like, so the um for to enable dynamic loading of new plugins on any node, which you need any class implement. Sorry, all class implementations are plugins, so when you, if you send a transaction to a node that hasn't seen that object or that class tree yet needs to be able to go load it, the class class file loader is what's used to go load a new plugin in and then establish that the class is there the technically the class instance data is on the blockchain already.

G

This is to load the code to run the class class x. Bom is now the root of all future classes, so just like class objects, move for all classes. Class x bomb is for everything related to the x-bomb environment.

G

Going down the tree just a little bit more. The class x-bomb container is what implements the concept of containment, parent-child relationship. This is literally a list of children with any any child can be another x-bomb container or sub-class and have more children. This is identical in concept to an actual window tree that you use every day and we're using right now the only difference.

G

Of course, this is not a user interface, it's a just, a straight object-oriented containment, environment and, of course, the class account which is a root for account is of type class x bond container, which means that it can contain objects. I have a picture of that. Further down on the left side is the part that uses what's known as a standard design pattern called a factory design pattern, which, of course, we named class factory not very original.

G

In a class account manager inherits from class factory, which means an instance of class account manager will have the uh ability to create new objects in the objects that you that it would intend to create would be accounts. So you would expect that the class account manager will create instances of class account or a subclass, and that's exactly what happens.

G

A little bit more on the bootstrap cycle, once it's created all those classes and, of course, there's a little bit of bootstrap class class file, loader loads classes, but you have to actually load class class file, loader first to be able to load classes, so that piece is actually done manually and then you can use it to load all the other classes which we do.

G

We then instantiate, two initial objects: the root dictionary, which is an instance of class dictionary. To give you a way to have a bootstrap to find initial ledger object, ids in the root account, which is what you need to use to be able to send messages to anything, all all messages sent to all objects. You are meant to. You have to send the message to an account to the object in the account with the method name that you're calling it a message name in the um input arguments for it.

G

So you need those two things to get it running and you'll see that shortly. This is what the whole thing looks like. So at this point, you're ready to actually now create an account. I'm actually going to go. Do this in a minute, and this is what an account would look like. So here's a root account object in this sorry. This is the root of an account. I'm using the wrong word root account. This is an account object. This could be a subclass.

G

This could be an instance of class account, as it shows, or instance, of a subclass of class account. It supports because again it inherits from the xbomb container.

G

It is perfectly possible to have any number of objects within that account in any object that also inherits containment also can be another object. Another child list. It's important to note that it's hard to diagram it correctly, but because the object, the ledger object, ids are not typed they're. All you can send a message to any object whether or not the object is of the right type or not. If you send a message, an object doesn't recognize, it will simply return. Not implemented means that all lists are heterogeneous lists of objects.

G

This is different than you'll, see in most object-oriented environments, which are trying to do that type of type checking at compile time. We don't do that. There is some type checking we do for um to make the message passing easier, but at runtime it's actually possible to send any message to any object.

G

Late, dynamic binding has some interesting capabilities that enable a different type of object-oriented programming that you might be used to. For example, if you write in java code here's what a transaction looks like um the database, we use whether it's a couchdb or leveldb, which is the hyperledger database. Unfortunately, I'm not familiar with hyperledger sawtooth's database, but I assume it similar runs a keyword, key value.

G

For us, the keyword is always a ledger object. Id ledger object. Id is normally the 256 sha256 value. In the instance data the data is actually the instance. Data of the object instance now remember that classes and meta classes are objects too. So the instance data for the class, the instance data for the metaclass are stored in here as well. We take advantage of that, as it says, on the right. We manage all of the inheritance and um the uh pulling the instance data off of the blockchain at runtime into transaction processing.

G

Anything that's changed is automatically put back on the blockchain. If you don't make any change in instance, data, then it doesn't make any update to it and because of the automatic replication of the database, you don't need to do anything else. At that point, going down the very straight flow transactions start you're, actually sending from a client the account object. The target object again. You you retrieve the ledger, object id so I'll. Show you how that's done the method name of the method, you're calling on the object in the input arguments.

G

The class major infrastructure does um first uses the object. Ledger object id the loid key to look up the object, make it walks up the class tree to make sure that all the classes are. There pulls all of the instance data out. So you now have a running object. This all happens transparently. The method gets dispatched to it.

G

The method does inheritance so that if the method is inherited from one of the ancestor classes, it will call the appropriate one, and then you can actually do um ancestor calls you consult, you can say, call ancestor and walk right up. The tree executes the uh code, which can include by the way, calling any other object in your environment that you're illegally allowed to, so that the transaction can consist of multiple changes to multiple objects. Instance data.

G

When you, when the transaction completes successfully, the data is written back to the database automatically, and then you return with a as long as there's no error returned. The hyperledger fabric will distribute to the other nodes automatically in the standard way. Just all of that happens automatically for you just a quick piece of that all sounds great.

G

How do we do this um to write a class in go, and I should make a note that, theoretically, you could actually write in multiple languages and even in your inheritance tree, you could have one class in play implemented in one language and an ancestor class implemented another language. We will actually build something like that at some point. We've done in the past, this was to get a proof of concept out as fast as possible.

G

You write your implementation piece in just classname.go. The these are, of course, conventional names. You don't have to do exactly that. It's just easier when you're, looking at your code in your class implementation file, maintains data type definitions, a method table which is used from message name to method resolution implementations, which are the actual code. That's called executed in some boilerplate, that's required to load and run the class.

G

The stub file is what's created and you you create these things yourself at the moment, although in the future, we would expect to create some of this with auto code generation. The stub file is what other classes use to compile against, to send messages to your two instances of your class and the skeleton file is what's received.

G

So the class major infrastructure expects a stub file a skeleton file. The class major infrastructure will call into the skeleton file with the method to call and the method will act. The skeleton file will actually then call the correct method. You write this code by hand at some at some point. Like I said we will automate it. You can see an instance of this in our open source.

G

um If I don't forget, oh, if I because I'll probably forget to say it, um xbomb.io is our website where you can register and then go pull down the open source for this okay. um What I'm going to do here instead of going to this piece again we're trying to keep this short, is I'm going to actually uh bring up and do a quick uh example of this loading?

G

You'll, give me one. Second, I have to start up my we run on a remote desktop on aws on one second.

G

G

And where's the share for this.

G

I gotta stop should start shooting right here. We go green and go.

G

Okay, you should be able to see my screen um what I've done up to this point, I'm using straight. This is actually a modified test network script, so I'm actually in the test network of the fabric samples, if you install hyperledger fabric, do a quick um demonstration of that. The original shell script, uh which was here, network dot, sh we've modified slightly to class manager.sh.

G

What we've done so far is just loaded up the you can just see up here. I've just loaded up the blockchain itself, so I have two pure nodes in an order running so, and you can see this as docker containers as the dockers running um I'll come back in a second, we did not change any of the source code for hyperledger fabric whatsoever.

G

We did need to do is build our own docker images, because the default um pure nodes for uh hyperledger fabric are built with linux. Images that do not dynamically do not enable dynamic loading of shared objects technically analytics that linux. That means that you need what's called the ld-linux.so library, and so what we did is simply change the root uh linux kernel, that's built into the docker images.

G

The reason it unfortunately makes the image larger than the very small ones that are done for hyperledger right now, but it doesn't change any of the source code, any the functionality of hyperledger.

G

So now we're going to do is we're going to run our bootstrap and because um we want to uh make the ledger object easier to see in the minute uh deterministic rather than random. um We have a flag uh which I've highlighted called loid. Let me paste it over here.

G

um That gives you a you, can put a random value in there. Every time you restart the hyperledger blockchain, so you'd always have a completely uh unique numbers within it any given chain for test purposes. We want it to be deterministic, so I can run scripts. So this force is a default value. That's all what this is doing. Here's our bootstrap. So this is now creating all the bootstrap classes. I have a nice uh very uh simple return message. All objects saved there.

G

That means that all of the classes, which are objects that are for the bootstrap environment, have now been stored into the blockchain. So all the nodes can use them. It means it did this standard thing sent out all the transactions um to the nodes and that's what the piece does here and sign them then send it back out. This pure capability does standard invoke all this. By the way we are using, the the.

G

As you can see, the chain code invoke command from the command line for this so everything's standard here, the next one would be now I'm going to actually get the root dictionary, and this is a built-in function because you need to bootstrap from somewhere and this that's what this does, and this will return the ledger object. Id for my root. Dictionary ledger, object id we return as printable numbers, but this is, of course a sha-256.

G

You could put this as uh hex. You know I could print this out in hex as well just how many printing out as integers in expected as integers, but you could just easily change that now, I'm going to go get the system account object, which is the object we were talking about a minute ago.

G

In the uh tree of showing earlier, you need a ledger object id for that, so you need to go collect those two starting point: ledger object, ids to do anything I now have something I can send a message to to ask things of, and so now I'm going to send the first message: messages are object, send and there's something also called object. Call which is internal to the runtime, but object. Send is you're, saying, send this message, here's the actually it's easier to see it in the black.

G

I think let me bring that over there, and this is, uh as I said, the style of making a call. There's a couple, more steps we'll be there.

G

If I forgot, you can't see the other window, sorry, so, in this environment we have class manager, invoke the arguments. Here's object, send here's the ledger, object id for the account right here, all the way across here's. The ledger object id of the object, we're sending the message to here's the method string, the name of the method, we're sending, which is class dictionary, get object by name and here's the parameter for the input arguments we're looking for the root account manager, which is an object instance.

G

That's been created to now be able to ask it to go, make a new account for me, and so it's going to go. Send that message. Return.

G

And when it's done right here is now returned to me the object handle of the object I want, which is root, account manager. So I now have an object that I can now send a message to the message I'm going to send I'll put that into one second is to create a new account.

G

Copy here comes.

G

And what this does so? Here's again, here's another message: here's and here's the account uh um object. Here's the target, object right here and you'll notice that this is the same as right here, which was returned so literally. I got the object.

G

Now, I'm going to send a message to it and now what I'm asking it to do, because I know that it inherits from class factory, I'm saying make a new object, that's a message that is implemented in class factory and so we'll inherit it, and the argument it takes is a how many should I make and of course I only want to make one at the moment.

G

And it is now made an object and here's the handle returned again: ledger jd. If you notice a little unique piece right here, there's a double bracket. This is because this would actually return an array of objects. If I asked it to make multiple, so it could actually um it's a class factory, but it happens to make accounts right here. So I could say to the account manager make me a whole bunch of accounts of this account type.

G

In one more piece, so I now have an object and the object is an account. It doesn't actually contain anything, it's a very short demo, um but obviously I could add new objects to it. The interesting thing is: how do I know what the methods are, what the classes are an object inherits from and what the methods are for those objects.

G

What we added in is the ability for inspection to return back jason's schema, so you know how to send messages to it, and so the message that I want to demo, for that is simply one that called, and this is implemented in the root class object, so all classes have it all objects. Have it rather class object, inspect, which is going to return, looks like a very ugly piece of of uh text, but in fact this is, if you pretty print this, you will see that this is standard.

G

Jason schema that it walks up the entire class tree and gives you all of the methods in all of the arguments in json syntax that you can use to send to every single class that the objects inherit from so you can interrogate any object, whether it's an object or class or meta class and retrieve this information.

G

So it gives you a very dynamic way to um manage. You could build dynamic user interfaces from it and things like that. um That's as far as I want to go, um please take a look at xbomb.io when you register on that. It'll give you the link to the um what we call hlfxbom public fiber, ledger fabric, x-bomb, public gitlab, and you can pull that down. There's a script to set up your environment in a linux environment we don't do windows and it will come up and run for you um and it's the same environment.

G

I use. Thank you very much. I do see there's a lot of questions I'll try to pull some up and look at them and let me stop sharing and mike if you want to take over I'll, take a look at the messages.

F

Okay, thank you very much dave for that. um I am going to.

F

Share one last time.

F

Can everybody see my.

F

F

uh Slideshow from the current okay there can everyone see my screen. I guess and hear me. Okay, let me close that up. Okay, so um the last thing that there was one question that came in I saw on is this open source? So there's two parts to this um for the developer: uh for the developer community absolutely 100! This is the class code in order to build classes and uh and offer uh it, you can commercialize anything um those classes, uh those con, your vertical specific class trees that you make whatever figure.

F

Those are your applications. Yes, that is open source. We don't expect any royalties any revenue or anything from anything you create there. What's not open source is what the cmi the class manager infrastructure and that will be a sas license to the enterprise.

F

This is not something we're looking for uh uh to the developers um uh to uh uh bear any uh costs on. uh We do have a channel pro uh also set up so that there is uh channel opportunities in order to uh participate with the organization um again. The class manager infrastructure is a uh a monthly sas license uh to the enterprise.

F

The class build code uh is fully open source um with no need to uh add to the project that your your whatever you build, is not open source that is fully commercialized for you, um okay, so next steps um you know we are starting. We are looking for proof of concept.

F

Now we are working with a couple of different organizations um here in the united states, uh um we're looking for uh application and projects, uh and uh you know, and the team uh to kind of work with uh document the proof of concept objectives and then work with us on poc design and testing.

F

uh We we understand that uh it's a new way to look at uh the architecture of blockchain and such so we're definitely um here to assist in in any way that we can so, um as dave said, uh xbomb dot io, uh you can go to xbomb dot, io and uh oops and register uh for access into our gitlab repository where you can download the code and play with it. We have on xbomb.io the overview page towards the bottom are three videos that go deep into uh the overview.

F

The functional overview of xbox on hyperledger goes into the concept of accounts and class or classes and objects, and then, finally, uh into the json uh um environment that uh dave uh built and uh you know, um telegram, presago official. um We also have uh the telegram chat and I believe this uh presentation will be available um after uh to everybody, so you can use the links there uh we do have. Currently. Support for uh developers is to our telegram uh um developer channel, which is the yeah go ahead.

A

Yeah, michael, so uh thank you.

A

Very important question regarding the x bomb and the uh I think you also may be aware: the dml and the kind of record project, so another person asking about how you will relate your xbone with the the digital asset and the accord project, because they also put some kind of abstraction at the same code level. Writing.

F

I you know, I'm sorry, I did not hear that question. Can you ask one more dave? Did.

A

A

I guess there's some network issues that combination.

D

Actually, there is a.

C

Question, like you, are doing the q a.

A

Portal yeah: there is a question on the q, a portal which they are asking. How can we relate x, bomb versus other solutions like what we see in the ammon.

A

F

I'll, let you answer that on the devil question.

G

So I'm not sure what you're oh, is that damn is what you're talking about.

A

G

Oh okay, um so the uh key difference for the um x-bomb environment, um for virtually anything else, you've seen in the any sort of smart contract or chain code or any other name for blockchain, is that the class code in in or in this case, actually the reference to the class code um is actually stored on the blockchain. So a class isn't exists as an object itself, and so the instance data tool class includes telling you what the message methods that it'll take are how to call the code and in the environment with go.

G

It also tells you where to go, find the actual uh plugins, but if it was in something where you're writing an interpreted language, it would include the interpreted code itself.

G

When you do an instantiate, an object, it will walk up the class tree and those are literally looking up the blockchain for each class, which is an object for reference to another class of its inheritance tree. So you only ever if you're, adding, for example, new capability you're, adding just a subclass you're, not um uh recompiling the entire environment, to do a single image.

G

So it's a different concept from.

A

Technical presentation is really nice informative. So now we have a next presentation from santhin and.

G

A

Is uh to talk about private data collection and, if you don't know the same thing senseless from the ibm research and contributed to the hyperledger fabric, and he also maintains his blog. uh He clearly writes about the hyperledger fabric and its concept in detail and who started you know hyper fabric following then he must be no.

A

A

D

A

Okay, so uh I just introduced you, okay, so yeah take forward.

E

Stop the presentation, yeah yeah thanks for the introduction, uh so this talk is about private data collection and hyperledger fabric, and this is available uh since version 1.2- and this was anyway done uh in collaboration with other fabric, maintainer mani, shethi, davinyarat and diyakovanatham.

E

So this is the argent of the talk. So first I will present the transaction flow involving just the public data. Then I will present motivation for providing data privacy within the channel. Then I will explain uh how the private data transaction flow works in a fabric, including private data dissemination, and how to define private data collection for a chain code.

E

Then definitely there would be a questions like how channel and private data compared to each other and what are the pros and cons when one should use channel and when one should use private data collection. So I will talk about that. uh Then I will dive into some of the implementation details, some more like an internal to show that how the code execute when there is a public data and how code execute when there is a private data, especially for the commit path.

E

Then I will talk about some of the performance numbers with private data collection and some of the optimizations that we have been doing and some we are planning to do it in the future to improve the numbers. And finally, I will conclude some ongoing work.

E

Okay, let's look at public data transaction flow, uh so I'm assuming that the audience are aware of smart contract endorsement and then state db some background on hyperledger fabric.

E

So here in the setup, I have four organization a b c and d, and each of them is hosting and beer, and then there is a state database and just for an example, there is a smart contract called yes that is hosted on all the organization and we have clients and we also have an ordering service and, in the right hand, side it just a committer only pair, which does not run any smart contract.

E

So let's say that organization b wants to submit a transaction. uh Basically, it is trying to put a store, a value like account id and then balance for that account id and depending on the endorsement policy for the smart contract, it actually stores the. I mean it submits a transaction to the organizations.

E

Then the transaction is simulated on the respective organization, then the simulation results as well as organization digital signature is sent back to the client. So the simulation results include many things, including the transaction message submitted by the client. But for us the key thing is the right set, so they also include the read set, but for simplicity. I have assumed that the smart contract is not doing any read so as a response to the simulation it just give.

E

The right set right set include the account id and then the balance number and digital signature is nothing but the endorsement here then organization, I mean the client collects enough endorsement and then submit the simulation results and all endorser signature for ordering and then order perform consensus to create a block of transaction.

E

Then the block is delivered to all the members connected to the channel.

E

Then the block is opened and then for each transaction. First, the endorsement policy validator is invoked to validate against the smart contract endorsement policy. So if you remember the client collected signatures right so that need to match the endorsement policy defined for the smart contract.

E

So if that is valid, then it goes into mvcc validation, it's basically a validation uh to ensure serializability isolation in simple. We can think of it like a double spend detector and if it detects something like that, it will invalidate the transaction. uh Basically, what it does is there is a read set and then there is a version for each key. It basically checks any of the read has been modified or not. It's it's a simple right.

E

If I have read some data and then decided to make some modification, but before the commit, if the red data has been changed, then obviously I cannot commit the data, because the logic might give me a different output. If I execute the program now, so that's why that's? What the mvcc validation does. If it is valid, then the transaction will be committed and then the transaction status would be sent back to the client. So this is the basic uh how the public data work in hyperledger fabric.

E

So uh in this setup there is a need for data privacy. uh Let's take a sample, blockchain solution that is uh supply chain network, especially here I am taking a food supply chain network, assume that there is a chocolate manufacturer.

E

uh Then, for that I mean, if I take the or the overall supply chain network, there has to be a farmer who is delivering the raw materials. Then obviously there will be a wholesale seller because the manufacturer may not directly buy from the farmers, because the old seller take care of contacting multiple farmers. Then there could be multiple distributors uh on the different retailers. Okay, so let's say that, uh let's, for example, let's take a single former supplier, manufacturer, distributor and retailer and they form a consortium and then start a blockchain network in hydrogen fabric.

E

uh So each of them could run appear okay, and so we need not go into the individual detail like what are the actions that can be possible. um So these all these actions are recorded in the blockchain and the key thing is um in hyperledger fabric, as we saw when a transaction is added to a block. The block is replicated to all the members, so every member get to see the data, so especially, if you see invoice and proof of payment.

E

These are like very sensitive data and, for example, if if the invoice sent to manipu manufacturer by the supplier is visible to the distributor, then distributor can kind of calculate the profit or even the farmer can do the same. So those data we cannot directly store it and one simple solution is to only store the hash so just to store the hash of the invoice or hash of the proof of payment.

E

And then we need to manage an external store and then keep the actual data and then worry about the synchronization between the data that is present in the blockchain and then data that is present in the offline store that had a lot of additional overheads, and even the smart contract cannot directly access the data that is present outside the the pair. So the name solution doesn't work.

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So if you think about it in a high level, what kind of solution that we need is so between the farmer and supplier? We kind of need a store that will store some sensitive, sensitive information that should be seen only by those 20. Similarly, for every two entity, I need some kind of private data stock. That would definitely solve the problem right, like a high level idea and then in the replicated ledger, we could store like order id product id, not id, and that could in fact be referred back to the private data collection.

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If I do hash of order id, probably I can get the invoice for the dot ready in the the former supplier private data. This.

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Level concept, so let's look at uh what is the exact transaction flow uh that uses private data, so I'm I am taking the same example, but now you would see two new boxes: one is private a b so here in this example. What I'm assuming is that there is a private collection between organization, a and b any data that is stored in the private.

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A and b will be only visible to these two organizations and it would not be visible to other organizations, and then there is something called transient db right, that's more like an internal store. When I explain the transaction flow, uh things would become very clear why the transient db is used.

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So let's take the same example, um so it's a storing of a balance for an account account id and the simulation of transaction happens here in the simulation. What exactly happens is that the account id and balance is actually returned to the transient db and then, when the simulation result is sent back to the client, it only include the hash of account id and then the hash of balance, because this is going to be included in the block and the block is going to be distributed to all the organization.

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So if I store the plain account id in balance, then everybody would get to see the value right. So that's why it kind of. I uh sorry.

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So in the step, two, the actual value was stored in the transient db and then only the hash of the value is sent to the client so that it will be sent to the ordering service for order. Then the ordering happens, block is created and then block is delivered. So here the validation happens as usual, and then there is a new step which is called the fetch private data. So when we talk about implementation, you will find out that when exactly the step 8 is executed, so basically each peer would check.

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So whether this transaction has a private data hash in the right set. If it has a hash, then it will check whether it is belonging to that collection or not. So if it is belonging to the collection, it knows that okay then there is, there should be some private data in the transient db, so it will try to fetch the private data from the transient db. So if you remember in step 2, we actually stored the account id and then the let me show that as well.

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So in the step 2 we stored it right in the transient db and then in step, step 8, it has been fetched, then the mvcc validation happens again. It happens on the account id and then the balance, because that is only is present in all the other organization as well, then the commit happens.

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So at the end, you could see that in the private collection, a and b, the plain account id and balance would be present, whereas the hash of the account id and the balance would be available at all the organization uh database. So this is how the private data collection works. So if there are any questions you would like to take, it.

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So there is a question, as trust is compromised to the privacy or other way of technology.

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Yeah, so bola has to have some questions related to a trust, uh so so basically, here uh see, for example, in a blockchain network suppose say there is a four member that is present in a consortium, especially the example that I gave.

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If there are competitors or present in a single channel, then obviously nobody trusts right, because the competitor could read my data. So even if there is some kind of trust, I don't want to take that risk. So the consensus in blockchain is mainly doing ordering. It's not really a.

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I mean the agreement, etc. It's simple ordering of transaction, so I wouldn't uh put a trust on the consensus. It's basically the ordering node is malicious or not and can be achieved privacy by using ipfs yeah. So one of the key, uh the reason for adding private data collection is that we do not want to rely on any of the external services to store the actual data and then store the hash in the blockchain. Because then, the smart contract cannot access the data that is present in the ipf's or any other data environment.

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Right especially, we did not want to do that. So that's that's our main goal to keep the private data collection within the fabric. Still, if somebody wants to uh use ipfs, they could do it, but they need to ensure that the smart contract is able to access the external world.

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um So sudhir has asked the question: can you mention the read, write and double sprint version validation for updating our private data, okay, uh so similar to public data, uh private data, so that, as I said, there is a hash right, a hash of the key and then the hash of the value that is stored in the public db? Okay, even this entries has a version number associated with it. So when a data is been read, it actually adds to the read set.

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What is the hash of the key and then what is the version iterate and then during the mvcc validation, because even the non-member has the hash of the key they can actually validate whether the version has been changed or not.

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So when we have a private data, it does not mean that other people does not have any information about it, but note that other people still have the hash of the content and we can associate any version number with it and we can do the mvcc validation and how is the concurrency handled while ordering, if two are sends update to the same account id okay.

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uh So currently the ordering service does not ah peak into the transaction, so ordering service just to receive a set of bytes and then the one main thing that it does is access control, whether the the submitter of the transaction is allowed to write to a channel or not, and then it creates the block and then send the block to the peer. And then in the peer there is mvcc validation right and currently we do it very sequentially.

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So we take a transaction, perform, mvcc validation and then put the right set into a memory buffer, and then we do the next uh transaction validation so currently kind of serial. So that kind of provide us a reliability, isolation level. What is the impact of business reporting? Okay, so um so, but when I talk about private data collection, obviously I don't want to show my data to others right, so obviously uh they shouldn't do any analytics on my private data. uh So that's that's my main goal.

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uh That's why I'm using private data collection, so obviously uh that wouldn't be supported. Okay, no more questions, so I will move on. So next is the private data dissemination and there is a push versus pull protocol and the way that how the private data is shared between the members. So there are two scenarios. First, I will explain when the push of private data happens and when the pull happens. Okay, so let's.

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In a setup in which the smart contract has an endorsement policy, saying r, gay and then rb, okay and then there is a collection with the member a and b and when the organization b is submitting a transaction because the the endorsement policy says that, to I mean the client can submit the transaction to any one of the organization. It is submitting to organization gate.

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So now the the simulation of transaction actually stores the private data into the transient db of, let me take the laser yeah, so it stores the actual private data into the transient db of our gate. But rb doesn't have that private data right so in the push protocol. What happens is that at the end of the simulation and the private data is pushed to the other member of the collection, so it pushes the account id and then balance number to the other organization and store it in the transient db.

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So during that validation and commit of a block, the organization b also can get the private data. So that's the push protocol and in pull protocol suppose say that the organization b is kind of unreachable. In the case, one then at the eighth step, when it is fetching the private data it will try to fetch from the transient db, but transient db would return, because the data is not available at the time. It will pull it from the other member and then it do the commit.

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So that's how the push and pull happens usually pull should be avoided.

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It's only used when there is a network isolation or there is- I mean the organization b is able to talk to the ordering service, but it is not able to talk to organization a to fetch the data through push or pull protocol, so only at the time the pull would be used, otherwise it shouldn't be. There is also something called missing private data.

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I will cover that in a very brief way, so let's look at how to define private data collection for a chain code, ah so this is the sample ah json in which we pass it along with when we instantiate the chain code. uh So first thing is the name.

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That is the name of the collection, and the policy is basically a num members of the collection and there is a required peer account that actually decides to how many number of peers, the private data need to be pushed at the end of endorsement and block to live is nothing but uh for how long the data that is stored in the collection should be alive. So this feature was mainly introduced for gdpr requirement, because in gdpr uh there is a requirement for keeping the data alive only for a short duration.

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After that the data need to be removed, but because we don't have the time concept in hyperledger fabric. So we kind of use block number that is the block height as the lifetime of the data and max peer count is again something related to the push protocol, and then there is a member. Only read and member only write. I will talk about it shortly. So for us chain code, we can have any number of collections, uh so there is no limit.

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uh But, however, there is a some physical limit based on the system resources and how many database couch db can add it. But I mean in order to create like four uh collections, we need to have the four kind of uh this structure, like name policy and all other parameters, so uh in one dot ex.

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So we didn't have endorsement policy for collection, uh whereas in 2.0 that we have introduced. So here I am talking about why we have introduced that. So let us take a scenario where there is a chain called called my cc and that is deployed on r1 r2 and then r3, okay and there is a collection, a and in which r1 and r2 are the members and the endorsement policy says that any one organization can submit a transaction here.

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So ah so, given that there is a collection, a and that holds a private data associated with arg1 and r2 only I mean it's. Basically, we cannot allow arg3 to write anything into collection, one right so because it's a store belongs to r1 and r2.

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uh However, before one dot x, if chain code hasn't returned any sophisticated access control, uh definitely r3 could submit a simulation request to r2 and then can write into collection a or the rf3 peer could manually. Create that I mean even the client could manually create the transaction right set and then put the signature of the peer, because the r3 has access to the peer and they can submit the transaction to add data to a collection a so we didn't want that.

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So that's why in 2.0 we introduced the separate endorsement for policy for the collection, so that in collection a we need to define endorsement policy with r1 and r2 as a member, so that r3 cannot do any transaction on a collection. Yet so we have three levels of endorsement policy. As you know, chain code endorsement policy is there then collection. Endorsement policy is what I defined and more fine grained is the key based endorsement policy, so that this endorsement policy also, we need to define as part of this configuration okay.

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So, uh let's talk about read, write access, control on collection. uh This is like a inbuilt implicit read, write access, control, still user can add, read, write access control uh by adding a code to the smart contract, but we added some future to the the configuration itself so that the peer itself enforces access control. So um the same example same scenario uh now say that arc three client uh I mean in one dot x r.

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Three client can submit a assimilation request to read some data from collection, a uh if the smart contract hasn't implemented, any access control on collection a so this kind of leaks, some of the private data right. So that's why in 2.0 we introduced something called a member member, only read and then number only right. So member only read if it is set to true the peer itself will check whether the submitter of the transaction is a member of a collection. If it is not, it will reject the transaction, it will throw error so earlier.

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The smart contract need to make this check, because that every smart contract need to have this code. We kind of made that code integrated into peer itself. Similarly, there is a member only write as well: okay and in 2.0. We also introduced other apis like get private data hash, especially this is used for moving data from one collection to another, but I am not covering them in details, but in fabric sample.

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Recently, there is a separate use case dedicated for this apa, as well as implicit collection, so implicit collection is like whenever a chain code is instantiated by default. There is an implicit collection with the peer, as the I mean member, it's like a so, for example. So here there is a chain code m, my cc that is deployed on three organization right, so by default the arc one has a implicit collection and then r2 also has a collection. R3 also has a collection. Only the respective organization can write data to it.

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Okay and this kind of add a lot more privacy, and so that's what so I I probably you should look at a fabric sample, because this itself will take. I mean more time to cover. So that's why I'm differing to fabric sample repo if anyone is interested in learning more about implicit collection and how to use git private data hash?

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Okay, so before that, if there are any questions.

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So there is a question from rajit. If you are maintaining the private data, then why do we purchase the data? Is there any case the data could be purchased even on the block to leave this uh set to minus one.

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So uh when the block to live value is set to zero, uh we do not purge the private data at all, and so the first question is like: if I mean, if you are maintaining private data, why we need to purge it right uh suppose say that I am storing some customer data uh into the blockchain and then the later the customer comes and says that remove my data.

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So that's the gdp or use case, so the customer can ask any time to remove the data, but we didn't have that feature like when you say that remove the data we we can. We could immediately remove it, but we didn't do that. So, instead, what we did is we provided a block to leave. So whenever the data is stored, the user can specify. I mean, like this. Data will be aligned in the blockchain for like a month, depending on the the block block, height or block addition rate.

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Okay, so there is a follow-up as well. I mentioning this because the mistake, we have to say, don't appear, but the gossip was not happening.

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Properly yeah, so uh usually the gossip uh I mean whenever the people set up the private data for the first time. Definitely there would be some error related to gossip, because when there is no private data usage uh there is some configuration like uh the endpoint gaussian endpoint that we need not to set, but especially when we are using private data and the private data is pushed and then pulled so that parameter need to be set so because of that because it doesn't need the public transaction and only it is needed in the private transaction.

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uh Usually people misses that configuration as a result. The data is not usually pushed to the other member. So if the configuration is set uh properly, then it should work, and I think recently the documentation is also updated to reflect that.

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So, okay, next question: how about client app get an access to the endorsement policy? So there is something called service discovery and there is also some apa associated with the service discovery at the sdk and the application can use those api to find out. What is the endorsement policy for a given collection or the chain code, and even they can find out that whether the chain code is deployed on a particular peer or not, etc?

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So the service discovery is the place to look for I mean, if you need to know about the endorsement policy and sunil, would you talk about adding a new orc into private collection as on need to know basis, and how would this sync up work? Okay?

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So when I talk about the implementation, uh so I will talk about how we are I mean doing that in the implementation site, but in addition to that, I am not talking uh explicitly about adding new or, but we can add new org and the new or could pull the data from the block one to the current block height. But I will talk about it briefly, because you ask that when I talk when when that slide comes so then one more question, what type of collection is uh private data stored in?

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Is it similar to stated ecosystem? Yes, um so the data is still uh stored in the state db. Only so wherever the public data is stored. In the same place, we are storing this uh private data as well. It's just a separate name space, so each key is just prefixed, which is a collection name. That's it. uh There is no other fancy thing.

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Then there are some other long questions. But that looks like a debating question so that I may not be able to answer it here. I think it's from galaxy m30. Sorry, probably we can take it offline because I need to look at it. It looks a little big okay. Let me go into the presentation.

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Sorry I mean the heading is wrong: it should be like a comparison of uh comparison between channel and private data collection. um So, let's look at uh when to use channel and then when to use private integration, so I have given the table so for your use case. You need to decide by looking at the table uh and so what is suitable for the use case that you are addressing so channel actually provide a transaction level privacy. So that's like a best privacy. I would say because the participant information is completely hidden.

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The data is also hidden because one channel cannot see all the data that is present in another channel. Unless the members are like I mean overlapped and the even the smart contract invoked wouldn't be visible because it doesn't have access to the block, whereas in private data collection only data privacy is provided, but still the other member can see who has performed this transaction, which smart contract got invoked and what are the parameter that is passed to the smart contract. So all those detail is kind of leaking some information and performance.

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When we use large number of channels. Definitely it is going to improve the performance because, with the channel there is a parallel processing of blocks. So whenever we process blocks in parallel, the resource utilization improves. As a result, the the throughput also increases, whereas in private data collection I mean it's, I mean it's still: a single channel block commit path and also compared to public data.

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There is a performance degradation, so I will talk about it shortly and with the channel there is a data silos, whereas with the private data collection, there is no data silos because we can change collection membership. We can remove a member, we can add a member and also we would be able to move uh data from one state to another, one collection to another collection, and then um can we automatically modify more than uh um I mean data present in more than two channels.

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So it's not possible, whereas we can do the same thing in the collections. So if we can submit a single transaction which can uh modify more than two collections provided that the endorsement policies match. So that is one advantage with the collections and development and management complexity is debatable. It depends on the individual is what I think, because in channel we need to track of number of channels and then pls etc, and in collection. Also, we need to keep track of number of collections, who are all the members of the collections.

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So, in my opinion, it's kind of equal okay.

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Yeah, so let's look at comparison between uh public and private data commit path.

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So now we will dive into uh internal implementation details. So, in the left hand, side there is a peer component that is involved only during the public data commit on the right hand, side.

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There are more components, because the private data has more number of databases and then storage, components etc. So in the normal public data. So when the block is received by the gossip it is stored, it stores the block on the block queue.

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Then it takes the block and then give it to the endorsement policy validator which actually validate the transaction based on the smart contract endorsement policy. Then it goes to the serializability validator for mvcc validation. Then it comes to committer. Then committer opens the block into block store, then apply the right segment to state db and then the index is created in the history database, whereas if, if we take private data, you can see that there are more components right.

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So one is private rights dissemination so that what is invoked during push and the pull of private data- and that is the one which takes care of a transient store as well, and there is something called missing. Private data reconciler and this is used in two places. One is neither push happened, nor full happened, because some network connectivity issue has happened. So in that case the missing data would be marked uh in a private block. Store like there is a missing eligible state. Is there right, so the entry would be made and then missing.

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Private data, reconciler pre periodically tried to fetch those missing data from other members, ah that is another new component and then in private block store. Obviously that is also the new component, because now we have a private data.

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This is mainly to store historical private data, and you could see that there is something called missing ineligible state, so this actually stores all the states. It's like a hash of all the keys and then the the data that is associated with collection, for which the peer is not a member. Currently. So that's why it is storing it as ineligible.

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uh So somebody asked a question right. I mean how the the data is pulled when a new member is added. So when the new member is added, uh the missing in ineligible state is more of I mean the the data present in this ineligible state is moved from this bucket to the eligible state packet. Then the missing private data reconciler will fetch the data from the other members.

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So that's how the addition of new member also happens, and then there is a purge db that basically stores the purge entry for each of the key and value if the block value value is non-zero and then in the state db, we store public state, hashed, state and then private state. So public and states would be same across all the peers, because that is present in the block, whereas private state would vary depending on the collections and whether this pair is a member of the collection etc.

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And then there is a history db and also there is a collection, config db, uh this basically stores all historical collection definition for each chain code. This is used during the pull and push, for example, if a new peer is joined, it need to access the historical value. So that's why we have this database yeah so before going further. uh I would also like to check the time as well as some questions so our own.

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So do we have more time or it's already.

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I don't come leash.

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So uh I think 45 minutes so how many uh minutes you.

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So if you give me 10 more minutes, I will quickly cover the rest of the content.

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Yeah: okay, okay,.

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Thank you. So uh let me quickly. Okay, I will take questions at the end, um so this is the exact block coming path, so I can make the slide available later so that you can actually look at it. So this covers the exact steps in terms of code uh that is been called for both the purple public data and then the private data.

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So let's get into performance analysis. So here we use four organization setup. Each peer is, each organization is owning appear and there is a private data collection with all four organizations as a member. So though, it's not a realistic one, but for performance benchmarking. This kind of give a simple setup for us, and still somebody can use this if they want to hide data from the ordering service.

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So still it's kind of remote valid, I mean scenario and we used a small bank benchmark, and so you can see there is a different set of apis are implemented in the chain code, and so this is the endorsement policy. I mean collection that we have used for our setup, and so we are, uh I mean all them all all are a member uh of the collection. So that's what I mentioned in the previous uh deck. Okay, let's get into the number.

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um So in this graph the x axis is the millisecond and y axis is the throughput that achieved so this millisecond is nothing but the block coming time. So, given a take given a block, how much time it takes to commit it. uh So, with the private data, the peak throughput was around 720 dps, whereas with the public data we could get around 1440 dps, obviously more than 50 percentage drop, um but we could improve the performance.

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So that's what we did so we introduced five optimizations um so again, so these are like low level implementation details, so so I'm covering in a very high level. So we do sting based comparison for membership check instead of doing policy evaluation that we did it in 1.4 and 2.0, and we also purge transient store in background rather than doing it in the critical path, then the commit to block store and the private data store is. It happened uh serially so that we could do it in parallel, but it complicates the recovery mechanism.

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Similarly, we can commit to both purge db and state db in parallel that also we did and use a cache at the transient store.

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um So with this optimization with each individual optimization I have mentioned what is the maximum throughput that improvement that we are getting, so you can see that with all phi optimization we could get till ah thousand three hundred and forty four tps, whereas with public data, uh it's a thousand four forty right, so we kind of close to the performance gap. So only six percentage drop in the performance for now, but unfortunately not all the optimizations are available in hyperledger fabric.

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So so I I think first two has been merged. The one and two has been merged and the remaining three uh we are planning to do uh once the ledger. Checkpointing work is done, so probably it will be available uh yearly next year, so you can track those. uh I mean jira items here for the rest of the optimizations. So currently uh we could get till 1000 dps with the private data collection, whereas with public data it would be like 1400 ps again.

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This is not an official number, because the number could vary depending on the machine, and then the mission configuration what is the use case and so many other factors. This is just for the setup that we have used. This is the number we are getting okay, and this is one of the main recommendation. ah So whenever you are defining a private data, collection uh ensure that the required peer count and max peer count are set in a way that the push itself is alone. So push itself is disseminating the private data.

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There is no need for pull, because if you use pull, then it could significantly drop the performance like 60 percentage drop in the performance could occur, so these need to be set in a proper way and also we need to set something called skip, pooling invalid transaction during commit to true. So this also helps in improving the performance and yeah.

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So we are doing uh more steady like when the new member is added, uh so how much time it takes, and also, if you have a large number of collections, how it is going to impact and also performance with implicit collection yeah. So with this I will go to questions.

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So uh so can one argue on the collection, but other are request, access to the data or a particular transaction? Yes, it's kind of possible. So for that what we need to do is we need to set the member only read to false when you are defining the collection and then in the chain code, you need to manage all the access controls, so even you could have a chain code managed state to decide when to dynamically.

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Allow permission for a particular member, for example, you could store some secret into the chain code and then you can share the secret to the other member and when the other member shared the secret, you can allow that member to read the data from the chain code so that that's kind of is possible.

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So the underlying transaction log would be different for our inside private data collection and for our outside the collection, having only but both being part of the change channel yeah. So if you look at the log, the log is just the block store right. That is the block, so the block would be same across all the pairs, so the block, because we compute hash. So there is a hash chain that shouldn't change or not.

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So that's why I said that we always include hash of the key and then the hash of the value in the block that would be consistent across all the nodes. Only the state db data could vary, so some peer could have the private data and some peer would not have the private data, but still the block store being the source of truth. That would be a consistent across all the peers and what was the block size during the performance test?

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That was the 100 block size and what exactly the purge db and the history db purpose. I hope the state db will be referred for and rate rate set for validation. So can you please clarify that point? Okay, uh so the perigee tb? What it actually stores is the the purge schedule for each key value stored in the private data collection. So suppose, say we defined a private data collection with the block to live as 10.

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It means that any key value that I store in the private data collection will be alive in the appear only for till the next 10 blocks. Okay, so in the paris tv we kind of create an entry saying that on the 20th block, commit this key need to be removed from the state db. So that's the purge dbe uh work, so it's basically stores all the entry that need to be removed whenever a block commit happens. So that's what the purge db work is, and the history db is basically an index to the block store.

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uh So there is a get history for key. There is a apa right, so using that api we could get history of his all value for a given key. So it's basically indexing to a block store, it's like a which file and then which offset etc. So that's not exactly the complete story yeah, so I think uh there are no more if there is one more question. So what is the block time for the performance test? That's one! Second!

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So all the performance tests I do- or I keep it at one second, because we also uh measure the performance like throughput per second right. So so one second is good for reporting performance numbers.

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Is it not advisable to use get private data? Query result while using private data keeping the purge in mind? Yes, yes, that's true, and even so that could be missing private data, also right, uh for example, if network partition has happened, uh then the the matching data would not be present in the state db. So even in that case they get private data, for you wouldn't return. Even when there is a purge, it may not return all the data.

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So that's why, with uh very clear I mean careful uh design, we need to assign the block to live under other data, but you are correct. Yes,.

A

Yeah yeah. Thank you something thanks for coming yeah, it's really nice and so much deep technical like.

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A

Oh, thank you guys, yeah yeah, okay. So uh next we have uh muhammad usama and he is going to talk about how the articulation work in the hyperledger, evolon and hyperledger avalon is a trusted execution framework, compute framework which is based on the intel sgx cpus. Where you run the you are some kind of services and programs in the cpu in clear memory. uh Some kind of privacy features so uh old to you, mohammed.

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Thank you very much so can you hear me clearly yeah very clear, okay, perfect, perfect! Okay, so let me show you the.

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Okay, so let's start um so I'm osama and um uh I'm going to talk about the formal foundations for attestation in hyperledger avalon, and if you are not familiar with any of these three terms, I mean this formal foundations or attestation or hyperledger lawn. I will give a brief overview and this work is under the supervision of professor christopher, and I would also like to thank my colleagues, russia, do france and scythe who were involved in this work.

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So the outline basically uh is that uh I will introduce uh the three terms that I just mentioned in the title and uh afterwards I will describe about some related work which has been done in this domain.

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And thirdly, I will talk about the current attestation mechanism, which is used in avalon, which is called as epid and the future testation mechanism, which is currently being developed uh uh currently being integrated in avalon, which is called as dcap. I will describe that briefly and finally, I will uh describe uh the formalism that we used uh in order to analyze that okay, so uh briefly about hyperledger avalon.

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uh Unlike the three talks that you have attended, it is a ledger, independent tool which supports a fabric and ethereum, for example, and at the moment and it the main aim of this tool is basically to improve the blockchain scalability and the transaction confidentiality how this is done. This is done by implementing the off chain a trusted compute specification, which is published by the enterprise uh ethereum alliance, and there are a different kind of trusted, compute possible, which are supported, for instance, zero knowledge, proof and multi-party compute and trusted execution.

D

Environment, prostate execution environment is the solution which is selected for implementing uh avalon, and there are reasons for that. So I will explain when I talk about trusted execution environments and before that, I would like to talk about the security paradigms and why is it important or what is new in this, so the data security domains? If you look at very high level, it consists of three main paradigms.

D

The first one is the data at rest, for instance, the data which is residing in your hard disk. The second one is the data in transit, for instance in untrusted, public networks and um the third one really is the new paradigm, which is the data in use which, when we have some computations being done on the data- and this is really critical because uh you need uh for the most part, applications need to have the data in the clear in order to operate or in order to do some operations or on them.

D

So that is why it is important, so hardware based trusted execution environments, basically are the hardware hardware-based techniques to isolate the data from the untrusted entities, which involve not only the os but also other untrusted entities. For instance. This is really important when you have uh an application and you want to run it in an untrusted environment such as a public cloud, and then you need to have some isolated uh environment being created for the competitions to remain confidential, and this is really where uh trusted execution.

D

Environments are good and uh various solutions have been proposed, for instance, intel sex amd, secure processor on dress zone. So these are the three major solutions for trusted execution environments. Avalon currently uses intel scx for the implementation.

D

All right, so what what is attestation and why is it so important in intel? Sgx uh attestation is roughly a way of giving trust to the challenger, uh the challenger meaning here that when we have the off chain computations, when we want the blockchain to do some computation off chain, then that is the challenger basically asking the worker to do that.

D

Computation and we want that guarantee or kind of a trust that the right application or the right computation is being performed inside the right platform so that we can have these guarantees and the kind of verification which is done here is for different entities, and one of them uh is uh a major one of them is that we know the identity of the enclave and the enclave representing here the uh protected region of the memory where the computation is being done.

D

So we verify basically uh that identity of the enclave is what we expected, and uh another important thing is the validity of the platform that the platform itself on, which that computation is being done is, uh is the correct one? Is the right one and it's not under the control of the adversary or, for instance, is not something which is being simulated and giving us the results. So we need to verify that it is the right uh platform.

D

uh This is uh very important because we need to provision the secrets uh to the enclave and uh before provisioning, we need to have some kind of guarantees that our enclave and the platform are really what we are expecting before. We can uh put our secrets into it. So we uh need to uh consider the attestation mechanism talking specifically about the attestation in intel scx, as I mentioned, that avalon currently uses intel scx.

D

So the attestation process in intel cx is of two types. The first one is local attestation, where we have two enclaves: oops sorry, so we have two enclaves which are uh inside that platform and they are trying to attest each other that both of them are residing on the same platform and the second one is remote attestation. When one of these enclaves proves its identity to a remote platform, then this is called as remote attestation.

D

uh Then we have uh the two main types of remote attestation, as I showed in the outline. So the first one is applied, enhanced privacy identification, and this is what uh the currently currently being used in avalon.

D

This basically is based on the concept of privacy that your identity remains hidden and then the second one is more in order to the is called decap data center attestation primitives.

D

So this is more in the concept of giving you making a full infrastructure of attestation where you do not need to contact intel each time for the verification of your verification of your codes and so what are codes. So I will explain that uh in the coming slides and the third part of introduction, as I described in the title, there are three things. So the third part is really this formal methods and uh what they do and why they are so important.

D

So here I have mentioned that they are basically some mathematical techniques which guarantee that the model satisfies its requirements. So we have, we represent the system in mathematical way and then gets that it's this model that we created has the satisfies the requirements that are done. So here is a motivation for that. Why we need forward methods. There was a security protocol, needham shooter protocol, which was uh used for 17 years and then after 17 years. It was discovered that this had a flaw in the protocol and this was discovered using foreign methods.

D

So you can realize that the potential of formal methods in security is really great, and uh this is really what we are trying to do, along with the implementation of uh the hyperledgerable on, in order to formally guarantee that the system satisfies the requirements right. So here I show uh the flow of uh what is done inside the form methods. In general, we have a system which is then out of that system.

D

Whatever system is given to us, for instance, let's uh consider this uh attestation protocol uh or at a larger scale the hyperledger avalon system. So we create an abstract model of the system, which is that, basically, we have created a mathematical representation of which of the system which we can analyze, and then we have the requirements here, the requirements, meaning that what it should satisfy and what we want is that uh this should be represented precisely in mathematical form, so that it can be verified.

D

So we call it here the specification, meaning that they are represented as properties. And finally, what we have is that we check that this abstract model satisfies these satisf specifications. Sorry uh and if it satisfies we have some results uh in the form of a verification proof and if they do not satisfy, for instance, then we have a counter example which can show that, under this scenario, the system does not satisfy the model of the system does not satisfy this specification and then we can go back and check the uh system model.

D

Was there a problem in the abstract model, or was there a problem in the conversion or the translation that we have gone done in order to model that? And then we can rectify the problem and follow this procedure repeatedly until we get that the proof of the system can be done.

D

So this is the overall idea of uh what form methods are, and this kind of work is not new. So there are some related works which have been done specifically related to attestation, and uh I will briefly describe the two most prominent of them. uh The first work was uh by a group of researchers at uc, berkeley and mit.

D

What they did is they proposed some uh an abstract way of formalizing attestation, uh but specifically specifically for intel scx. They do not provide the proofs, and this remains a gap. Then intel has in some of the documentations mentioned about some of their works, that they have done for this and some of the tools that they have utilized.

D

In order to verify this, and, uh for instance, uh they mentioned that they have some sequel for this in the sequential settings they can use this deductive verification framework, which is a tool developed at intel and otherwise for the concurrent settings in which we have multi threads so executing. In parallel this, they have developed this ipf tool, which is a graphical framework and its automated version, which is called as accordion.

D

So the problem really here is that uh these tools, the three tools developed by intel, which they mentioned in the literature that they have done for the verification of uh intel scx, remain out of the reach of uh the normal public and so that they, the a normal user, cannot have the guarantees that it was, or let's say what was verified and what kind of system order was there.

D

So this remains a limitation and a lot of uh new attacks have been uh discovered after uh in the last few years and that limits the confidence of the user in intel scx. So that's why we need to provide some more guarantees to the system, and this is what we really do by making use of an open source tool and uh allowing user to get more confidence in that.

D

Okay. So a brief comparison between uh the proposed approach, what we did and uh what was proposed, uh as I showed in the last slide about the three tools by intel. So the first comparison on the basis of concurrency dvf. Does not support uh concurrency, so it is sequential, as I showed last uh in the last slide and uh ipv and accordion, which were for the concurrent settings.

D

They do not allow non-determinism and, as I already mentioned so, none of these tools, as well as the proofs that were done, are not available to the public and uh just to be fair. So our proposed solution is, uh does not have uh too much implementation details.

D

The idea was that uh to verify it uh to begin with, to verify it at the symbolic level and then uh maybe as the implementation details or more details are available, then we can uh move it to the implementation uh tools as well, so briefly uh about the current attestation mechanism. First, that is uh in use in avalon currently. So there are a number of entities which are involved uh here, so I will give a brief introduction of uh all of these, and then I will describe the uh protocol.

D

The first one is application enclave. So this is that protected region, isolation, environment which is created by intel sex and the second one is the application itself that is, uh uh and then the coating enclave qe. Basically this is the enclave.

D

This is the intel architecture, enclave which is provided in order to verify the reports and um in order to, and then if the reports are correct, they after verification, it can sign the code signed to sign that report to generate the code um and then, finally, this is uh the provisioning certification, encrypt pce, which is uh the local certificate authority for um this quoting enclave.

D

And so these four entities basically form the user platform and uh the challenger on outside the platform is basically that entity which is trying to verify that the code or the application is running inside the enclave. So this challenger or the relying party is uh that entity and finally, in appid, we have this intern attestation service. Ias, which represents uh the intel uh architecture, which is um going to verify that the reports.

F

D

uh uh Sorry, the codes so after conversion they are outside the platform. We have these codes, so I will describe in the flow later. So what's the difference between these and then there is a communication between all these entities, uh how they interchange uh information with each other and uh that I described in the next slide.

D

um So we have all these entities uh again enter coding, enclave, uh the sex application, enclave, scx application itself and the remote challenger, or what I mentioned as uh uh in the previous slide as a challenger here: okay and then the internet attestation service.

D

So uh the process starts with the remote challenger and just to remind you, the intercoating, enclave uh or sorry, so the scx application enclave, basically in case of uh avalon here, represents that worker, which is doing that uh operation. So the process starts here with the remote challenger, which sends a challenge including announce to the sex application.

D

uh Then the scx application will give information to the application enclave about the mr enclave, which is basically uh the uh hash of the information, and uh this basically is uh this qe corticon cliff is what I mentioned here.

D

That will be the target for this report that will be generated by this worker so and the only target which is mentioned here, as I will show next uh in the next slide- that only the target which is mentioned here will be able to verify that report and no other target will be able to verify that report, because it is based on the key which is important.

D

Okay and then uh uh this will uh the sex enclave uh or the worker will then create a report which will uh itself contain the mac over that setup. So, basically, uh inside this uh local attestation or user platform, we have um this. uh We are using the symmetry key, cryptography and or and specifically using the mac to protect the data, and then this report after generation is sent back to the application. So I will just quickly switch to the next slide and then I will come back off about uh how this report is created.

D

So the generation of report is uh here, as you have seen, that it needs some target information, as I mentioned that it needs the mr enclave of the coating enclave, which means that that particular information is added here and the key is basically derived based on that target information, so which means that only the target, which has which will add that and have this information already in its enclave control structure, will be able to derive that key and will be able to uh get access to the uh uh data uh or sorry uh we'll be able to verify that mac.

D

So the process, uh in short, is uh like this, so uh the report body is uh the major part of the report and other than the report body. We have two other fields which are, and here I show that the report body becomes a part of the report. We have the value for the key. We are out protection and finally, we have the mac, which is generated by this process.

D

That is that becomes a part of this report, and uh this pack is actually could get computed over this report body and the key used for this uh uh computing.

D

This mac is shown here, and uh what I want to show here by this sort of ugly looking arrow is that in the beginning, the value for key field protection is stored in the temporary report buffer and then that value is actually used because there can be an attack in between, so that value is then used in the derive in the derivation of the key and uh other than that. We have this target information, as I mentioned uh previously, which is coming from um the application which describes.

D

Who is the target for this, for whom this report will be created, and then there are some other data like uh which will be involved for this key derivation and uh based on that this derived report key will be generated, and by target I mean this is specific to that target. No other uh enclave will be able to uh you derive this key right and then um I think, that's all, and I come back to this slide where uh so. This was the process which uh I showed here.

D

The creation of the report containing the mac and uh this report will then be sent back to the scx application, which will forward it to the internal coding enclave, and here you can see that this report will be verified because it was targeted for this coating enclave with this, mr enclave, and then it will. In this end, I will now switch again to uh this slide.

D

So what this will do is a similar process uh for this uh for this key derivation, because um instead of this target, information like it will use its own information from the sccs register, which is the scx enclave control structure. So uh so, basically it will use now it's on and now uh because it was uh at the center end because it was generated using the target information and now it can use its own, mr enclave.

D

So basically the same key will be generated at this end and coming back so it can basically compute or calculate this key and based on that it will compute the mac with that key. It will compute the mac over that report body again and if the two mac matches, uh if the two max match, then basically the report will be verified and once the report is verified, we can then uh check the hash values inside that report.

D

And uh if everything is okay, so it will sign it with the applet private key uh which it has been provisioned by um the provisioning certification enclave. Here, as I showed that this is the local certificate authority for this, and then this will generate after signing, this will generate basically a quote and then that will be sent over to the sex application and which will just forward it to the remote challenger and now since this has been signed with its private key.

D

At this end, it can be verified uh using its public key that uh these uh data frame is actually correct and uh or the report or the code actually is correct and then, uh after the verification of the signatures, it can also verify that the unpaid status and everything is okay and the platform is not simulated one and so.

A

D

So it's uh it! The appetite mechanism basically depends on the internet attestation service, which adds some lag to the verification, and due to this uh due to this limitation, basically, uh whatever loan is uh trying to do is to basically switch to uh or provide a secondary mechanism for a test station, which is this decap or the data center attestation primitives. So I will briefly describe about that.

D

So all the entities you see here are uh actually the same except this one, which is the intel attestation service, is actually replaced by this caching service, and what this caching service represents is that you have a local service which which can be at different layers, and what this can do is that you can uh verify your.

D

So you have a local infrastructure and there you have cash that you cash all the certificates which are required for verification and all the refocus, and based on that, you can actually perform everything uh in-house. You do not need to contact intel each time for the verification of the codes, and this actually solves the availability issues uh like, for instance, if uh internet station is not available, then you are stuck, and so this basically solves that availability problem as well as leads to an increase in the performance all right.

D

So basically, uh here we have uh this kind of a flow of the attestation process.

D

Where uh you see a couple of libraries are involved, which are code provider, library, and uh it also consists of the code generation, library and provisioning certification enclave, which is the local certificate authority for this coating enclave are both part of this library, and these libraries are basically to support kind of provide you the template, which you can utilize for uh creating that infrastructure which decap is used for and then the process is like this, that application application um uh yeah so at sex application basically uh wants to get the sex target information which is uh like in the previous, uh and we had this application, uh which had that information uh to begin with, which was the mr enclave of the coating enclave, and in this case uh I've elaborated the process here, which is uh uh here that the coating enclave will send its pck, meaning this provisioning certification key- and uh this is the private key of uh pce provisioning, certification, enclave, and uh this will, uh when uh and the coding provider code provider library.

D

So he will provide it back with the tcp and the coding enclave certification data and based on this tcp, which is uh received, uh it will generate its uh estimated key pair, which is this.

C

D

Key and its public part, so after uh at this uh key pair, is based on tcp, so whenever tcp changes. So basically, these keys will also change, and, uh after using this uh after generating this key pair, uh that will be sent.

D

This public part will be sent over to the provisioning certification enclave, along with the quoting on claif id, as well as the pcb, which is a widget obtained from this code provider, library and the pc on this end will generate the its own key pair, which is pck, and this its private key and its public part and then sent over a certificate back along with its public key and the coding enclave will then send its uh target information back to the application.

D

So it has now uh that the application now has this target information which it can send to the application enclave and the application encrypt can now create a report um based on this target information.

D

And then this report will be sent back to the application, which will send it back to the coding enclave and here the process. Afterwards it is a bit similar. There are uh a few differences which I will uh show in the next slide.

D

uh Basically, what happens here is that uh it will verify the report as before, because this target information is now available to it. uh This report was basically generated with this specific target, which is this quotient enclave, so it can verify this report. The concept here is again the same, but now the it is based more on the certificate chain rather than this epic private key. So uh then it will, uh after the verification of the report, is everything is fine.

D

Then it will sign the report body with the attestation key, that is its private key and uh it will generate a code and send the code over to the sex application and then so. This can be used to verify using the certificate chain based on the root certificate, and the attestation process will then complete.

D

So I now give an idea of the structure of the code um how it is built. So the main thing here or the main kind of fields which are important here are the involving the security version. Numbers coating enclave, as I mentioned, is a part of the intel architecture. Enclave and it is its security version. Number, is important in order to see whether this is up to date or not, and it's local authority that is provisioning, certification, enclave.

D

We have its security version number and then the user data field can be used to communicate the keys in order to establish the channel, and then we have this, uh the actual report body which was generated here so meaning that this report, and then this code signature data length, because this field, this code, signature data, is a variable length structure. So we need it's uh to store, also its data length and uh this code.

D

Signature data itself consists of all these fields and uh important here is also that we have a report for the coating enclave, which we can check, that it contains the right environments and everything. So we need also the public part of the testation key and another important thing is this coating on clay certification data? We want to check what what kind of uh certification we want and the size and the certification data again. This certification data can be variable length, so we uh send its size along with it so yeah.

D

So now I will describe the proposed formalism, which we have uh selected in order to formally analyze it, as I mentioned in the introduction that um so we uh deal with the formal uh we analyze it using forward methods in order to provide some mathematical guarantees.

D

So I here now describe what kind of organism we have selected and the reason for that.

D

Okay, so the workflow of the approach is like this: we have a system configuration consisting of all the entities which are involved in the attestation protocol, uh whether it is epic or decap so, and you have seen that for epic, there was internet attestation service for dcap. There was this caching service and some extra code libraries were involved. The operation policies basically captured the communication and the computation done by these entities. So there are two main things like uh what kind of computation is being done by uh each entity.

D

um That can be uh uh so. The computation can be modeled as a function formally, and the communication is modeled by using the channels and based on these three things.

D

By three I mean this communication and the computations, and here the entities um we can generate the symbolic model. uh That is uh so so, if you remember the beginning slide of introduction, we are. We are on the left side, where we had uh model of the system or the system itself, and then we create a formal model.

D

So we are on that step where we are creating the symbolic model, so the symbolic model uh we generate is uh or the formalism that we use here is the applied by calculus, and the reason for using this is that it is um uh it is.

D

um It has more information as compared to using a simple tree, automata and uh otherwise uh also it provides you guarantees for uh unbounded, number of channels or unbounded number of messages, and it can create unbounded number of sessions between these entities so which are the kind of currencies that we want to have so on the right side, as uh I showed before so then we have the requirements in the general terms. Now we have the security goals. We are trying to uh uh what kind of goals we have from the security perspective.

D

It can be confidentiality, integrity, for instance, and we formalize that again in the form of security properties or specify them as security properties, and we combine these two and what we do here is an automatic translation of this uh symbolic model into uh that there is an automatic tool which can do that.

D

So I will uh that is named, as pro very, for instance, can be utilized and which is what we utilized in order to do this translation to the horn logic and basically the symbolic model, is then represented by the horn clauses and uh the security properties are then represented as the derivability queries on these horn clauses, and then we have a process of resolution, which means that we check whether now these derivability queries are derivable um on these horn clauses or not.

D

So if in case the effect is derivable um on these horn clauses, then we try to perform this attack reconstruction at the pi calculus level, which was this uh model which we created, and if that succeeds, there are two possibilities.

D

So if that attack reconstruction succeeds and this box, I have made basically to show that this is automatically done by many tools, improving progress so which is the one we utilized, and if this attack reconstruction succeeds, which means that this uh reconstruction at the pi calculus level, which was this model, is correct, and then we have uh successfully found a counter example to the property. That is, this property fails on this system.

D

This given system for a specific reason, which we can then explore what was the reason for the failure of this property and uh because I mentioned that uh the kind of currencies we are getting are for unbounded number of sessions and unbounded number of uh messages between these parties so which, actually, uh you can imagine, a large state space, and uh it is really possible that the tool cannot reconstruct the attack at the pi calculus level, and in that case it will result with, don't know. So.

D

We have to then uh go and check in depth that what are the kind of problems which are possible here and then another possibility here- is that uh I I mentioned here the case when the effect was derivable and then, if the fact is not derivable, which the tool will return as true, which means that basically, the security goal that we were trying to verify on this specific given model is actually true or actually. This security goal is satisfied, so um yeah right. So the challenges in specification of the protocol itself.

D

uh uh I must say that uh the literature uh and even the uh formal documentation which is available from intel is uh not so well uh described, and that is the kind of best words I can use for that. So, for instance, this is uh uh intel sex, explained document which is uh in fact the most cited documents in the literature and about the report key derivation.

D

I described you the structure of the report and this claim that the padding for this report derivation is for the case of ed report instruction, which is basically for the generation of the report, where I described you that that it has a target information coming to it. So in this case they claim it is hard coded and in the case of e, get key instruction.

D

It is obtained from sccs while we explored the enter software developers manual and uh 2019, as well as its older versions, to figure out what was the kind of uh reason for that, but it is actually the reverse, uh as evidenced by this uh intel's literature.

D

So, as I mentioned, the interliterature itself contains some problems, so there were various ambiguous statements which uh we could not figure out what uh they wanted to mention, or were really the motivation for going for the formal methods to understand more about uh how the process actually happens.

D

For instance, they write that the quoting enclave report is a report when the quoting enclave report is certified, uh which absolutely makes no sense to us, and not only that there is in fact a lot of inconsistent information, which is there in the intel's official literature uh talking specifically about this remote attestation process. So there was really a need for a formal specification of or a precise description of the protocol itself and based on the recent attacks in the last few years and how to come up with a better or a secondary attestation mechanism.

D

So what we did is uh now describing the right part of the flow just to go back a little bit. I am now describing this uh security goals, how we formalize these properties and uh then how we can adjust an overview of uh how this process, uh how we model that okay. So basically uh confidentiality of the data is very important in this case, as I mentioned, that it is the main aim of a hyperledger avalon in order to provide that and the specifications um in order to meet the specifications.

D

And the challenger basically in this case again represents that uh remote party and it has uh when it sends an encrypted secret um to the platform. We need to ensure that the data is not available in the clear to uh in the clear to the attacker, and this can be represented simply as a reachability property.

D

So reachability property, meaning that we want to explore a state in which we want to check that uh there is there any state in the system uh where an attacker can get hold of the secret. This secret, which was sent in encrypted form uh in its plain text, form uh uh to the attack, is available to the attacker or not so. uh The second important property is integrity, and uh here we had to uh um uh so the way of uh doing this uh uh or a simple way of doing.

D

This is to have a couple of states which are the events uh which is called in providing so a message unchanged event and a message accepted.

A

D

Just imagine like two entities are talking to each other and when we have a receiver, if we a receiver, can check whether the message is unchanged and a state where a message is uh accepted by the receiver. So for every message that is accepted by the receiver we need to have. uh um We need to have a state for which the message was unchanged, and that provides some guarantees, but the problem is that there can be multiple messages which can be accepted corresponding to this message, unchanged, state so and formally talking about formal languages.

D

So this will be called as correspondence assertions that we check the property that for every message, which is accepted by the receiver.

D

There was a message unchanged even before that, and uh here have uh uh duplicated that uh same scenario, and uh what I want to show here is uh the solution to this is that we have a one-to-one correspondence between uh message.

D

Acc is the short of this message accepted and unc short for this unchanged to fit it here in the single line. So uh what I do here is that a message accepted uh for each message accepted event.

D

We can have a correspondence, uh the corresponding um a message unchanged, even so that now establishes a one to one correspondence between that and now I can check that, and this scenario will now no more be applicable, that multiple messages will be accepted by this unchanged uh uh from this same message unchanged event, so this is kind of uh an overview of how uh we can view from uh overall uh scenario.

D

This injective formally called injective correspondence assertions, and, um additionally, we need to check here that uh the reachability of message accepted event is also there, so why we need to check that. The reason is that, if this event actually is not reachable, the query will still result the answer of two which will be misleading because uh there was no uh message accepted and then but the event says that uh or but the tool says that um this- uh that everything is good sort of right.

D

So so, basically, what I mean is we are checking the property that for every message, which is accepted there is uh there is a corresponding message unchanged before that and when, in the case that we have no message accepted at all, it will also return an answer of true that everything is fine. But that is not what we want. We also want to have some message accepted, and then we want that for each message accepted, there is a corresponding message unchanged event right. So that is why this uh we need to.

D

In addition to these injective correspondence assertions, we also need to check the reachability of a message accepted. So this is the kind of overall at high level and idea of how we verified the properties for um uh using this uh providive tool.

D

And uh now I summarize the work uh so we have. uh We know that so avalon is a tool for improving the scalability and the confidentiality, and uh we have seen the specification uh or the flow of the entered sex, epid and decap the two attestation mechanisms which are provided by intel sex, and I also want to mention that um intel sex has been selected.

D

But it is, uh of course not the only possibility the development currently has been can be implemented on other trusted execution environments such as amd secure processor, and during this process of specification we have discovered various discrepancies, even in the official literature, as I mentioned a few of them, and we analyzed the confidentiality and the integrity on the symbolic model.

D

Two most important properties, which are important in the scenario, for instance, the confidentiality that our data remains protected and the integrity that our data is unchanged and the future work that we have in this particular direction is um like intel recently uh released or not. Release actually announced uh its trust domain extensions and uh there they give more uh power to the trust domains which are in comparison to the legacy virtual machines, and they have actually released uh also the specification documents uh and uh we are going through that and we have.

D

uh We can foresee.

F

D

Actually, in the future, intel is going to uh utilize uh that for a combined attestation mechanism between uh the trusted domains and uh the scx framework, so uh probably that is going to be uh in use um for both of them, and uh but there is currently, uh it is not in the timeline for avalon to move to that, and uh otherwise uh one of the things uh we did not consider in this work was uh about side channels that we do not uh deal with these and we assume that uh the cryptography is perfect and uh the reason being that the indian sex model itself uh does not cover the side channels.

D

So it is the responsibility of uh the enclave developer, for instance, to ensure that there are no vulnerabilities inside the enclave and side channels cannot be exploited, but of course they can be considered, and there are various mechanisms which can be utilized for that.

D

There are different tools available for that also, and there are information, theoretic concepts which can be utilized here in order to provide uh some abstract guarantees, at least, and finally, as I mentioned, so, the implementation is not limited to intel sex as a secondary thing.

D

We can uh provide some uh guarantees uh using uh or some implementation using some other prosthetic execution environments, including the amd, secure, processor and amd, has also recently released its suv, snp version, which is providing also many guarantees, including the remote attestation, and there it would be nice to explore how uh or what kind of guarantees or additional uh things we can get from that uh amd secure processor.

D

Before going into the detailed uh development phase it is, we can have a idea from the former model that how it can be useful- and here I list a few of uh the key references which are uh which are used in this presentation. So I mentioned about intel, stx explained document, and these are the two tools which intel where intervention their tool uh tools and uh there are some software developer manuals available and um and these are two papers, so we can uh so these are available and you can go through them.

D

All documentation is available, and uh so thank you very much for your attention and um you can contribute to hyperledger avalon. I have the link here.

D

The slides will be available and, uh of course, you can google that hyperledger on- and uh we have here- also a link for the project updates, what kind of formal the kind of formal guarantees that we are providing and to deal with the attack station mechanism formally and then to provide a better retestation mechanism in the end in order to utilize, and uh of course I will try to answer the questions that I can now and otherwise, if you have any question in the future, you can contact me by email.

D

So that's all from my side and um see if you have some questions.

A

So I think there are two questions like why we are using symbolic model instead of computational mode.

D

Okay right, so that's an interesting question, so um yeah. So basically uh the reason for using that was that um it's always good to start at a basic step, so symbolic model and the or, if I go back to the slide just a moment, so, okay, so this one yeah, the symbolic model that we generate uh can be utilized for the computational model. Actually, and uh but it is not the reverse.

D

So for computational model, the first thing is or the first problem is that you need a lot of details which until unfortunately, has it made public so the symbolic model and was very basic and was a kind of starting step where we could uh go ahead with that. And of course we can.

D

When we have these details and uh we can go to the computational model in order to get some further guarantees for that.

A

Yeah, thank you. So I think there is no question yeah.

A

Thank you sama. It was very impactful.

D

A

And so that brings us to end of the part one of our four weeks, three three part session and then next week we have interesting topics lined up as part of our event and then on in next week. You will get to hear about the production grid deployments and the tools around which using which you can deploy a production grid, hyperledger fabric network, and then how do you measure the performance once you deploy the network?

A

How do you visualize what's happening in a blockchain network using explorer tool, and then we will also have a blockchain automation framework, which is an automated deployment tool which was contributed by accenture and now it's in labs.

A

They will be speaking about the things which are considered as part of vaf and how easy it is for us to deploy a production grid fabric network, so interesting topics lined up for next week. We will share out. I have put put a registration link for number seventh event and then please feel free to ask us any questions. Do look out for our linkedin notifications, posters and today's event will be posted on youtube channel.

A

Yeah, thank you all. I think we can wrap up now.