Hyperledger Foundation Meetups, 16 Sep 2021

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From YouTube: Privacy in Hyperledger Fabric

Description

A virtual meetup hosted by Hyperledger Frankfurt on September 16, 2021 with Daniel Szego speaking about privacy in Hyperledger Fabric. In this presentation, he covers some of the possible privacy concepts, ranging from channel, or private data collections to more advanced structures, like transient field or design patterns using organizational private data collection with explicit information replication.

More about Hyperledger Fabric is at: https://wiki.hyperledger.org/display/fabric/

More about the event is at: https://www.meetup.com/Hyperledger-Frankfurt/events/278427875/

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#Hyperledger HyperledgerMeetup #Blockchain

A

So hello, everybody good afternoon, everybody. uh This is danielle.

B

We're gonna do uh this hyperledger meetup, uh I'm not quite.

A

Sure about the location, I mean it's, it's always difficult, this time with the location, I.

B

Think started for somehow in with hyperledger frankfurt, but it's it's pretty much actually uh advertised throughout the the continent. In several cities.

A

As well so yeah, I would say it's like you know, I mean we are in the we descent for european times. So, basically somehow in the continent.

B

uh But basically this is hyperledger meetup. um You know I apologize uh it's for the consortium blockchain and partly already a little bit for for public blockchains uh scandals.

A

As well, what I'm going to talk today.

B

About is the privacy in hyperledger fabric, and, uh with this brief introduction.

A

I would like.

B

Just to cover some of my content, uh basically I leave the chat here because otherwise I usually I just don't- don't recognize this. If anybody uh asked me questions so basically uh anytime feel free to interrupt me and and have questions either in chat or actually uh without you as well. uh I hope my audio will will be working uh well as well.

B

So basically, uh let me start uh with hyperledger.

A

B

Basically, as you know, high pleasure fabric is is one of the oldest uh uh project actually uh with hyperledger uh it's a consortium, blockchain uh platform already uh started by high collagen and by ibm and digital asset as well, uh but at the moment, basically, it's actively uh managed by by hyperledger and ibm.

B

So as the content, uh which is gonna cover a couple of like structures uh for privacy, and these are more or less the classical classical structures. So I won't go very much into the details of like advanced cryptography, uh especially not in the algorithmic details. uh This is going to be more or less the standard structures, so basically the first one is channel.

A

We're gonna talk about like.

B

uh The second one is private data collection and basically private data collection is yeah. Let me put it that way: it's it's more or less well-known concept, but it's pretty much tricky to use so we're gonna iterate a lot of uh on private data collections, especially like if it can be attacked by by dictionary attacks because of the hash and the answer.

B

Of course, it can be attacked um with like a little bit like topics like transient field and and private data collection, uh something's about private data and the endorsement just as a slide and there's a brief demonstration of we're. Gonna cover, uh adamics uh identity, mixer and we're gonna see some advanced patterns.

A

B

And different endorsement strategies, uh we will have brief uh demonstration in the middle as well, so I basically have a demo uh set up uh and then I will show some of the some of the concepts live as well. So this is actually the agenda. This, that's the that's the content. For today uh I prepared basically a demo.

B

It looks that way on github, uh so this is basically an old demonstration from me. I started somehow like one year ago for for for demonstrating concepts of of hyperledger fabric and kubernetes, and then, after that I just used the apple for for.

A

B

Further demonstration purposes as well, so you find this repo. It actually contains uh some old presentations from me regarding hyperledger fabric and kubernetes, somewhat presentations regarding basically high pleasure fabric and monitoring, and I just built in some concept regarding high pleasure fabric and privacy as well. um So that's actually one big demo uh for a lot of things. Basically, so you find everything on github and- and this is the url of course- so let me start by on the one hand, by a little bit introduction and basically covering the first privacy concept of february.

B

So basically uh this is hyperledger fabric uh from uh from an architectural point of view. So if we speak on like architecture, we can always consider like like two layers of hyperledger fabric, and one is the physical architecture. The second one is a little bit like the ideological architecture and it's important to understand the physical architecture of especially if we speak about like privacy, it's because uh most of the privacy concepts or most of your privacy or private data can be leaked actually uh because of the architecture because of the consensus mechanism.

B

So these are actually the basic items and so what's important to know that basically hyperledger fabric uh has this architecture because of the consensus mechanism, so the consensus mechanism looks that way. Somehow we got a transaction somewhere from a client and basically this transaction will it's actually not a transaction. It's a transaction proposal, so transaction prop.

A

Was a pro cause, some kind of a change on the.

B

Blockchain um and that can be accepted or denied, or not accepted in in a sense, so first, this transaction proposal will be sent to the peers uh peers of different organizations, whereas the chain code chain code is basically the smart contract and what what's gonna happen for the first run is that chain code makes a kind of a simulation, so it doesn't actually execute the code, but it just simulates. What would he happen uh if we just execute this chain code?

B

This smart contract logic uh based on our transaction proposal, and it gets some read, write sense, uh read write set, is basically like a set of atomic rights, uh reads and writes. So what would happen if we just write this, this atomic reads or if we read these atomic reads or write these atomic rights to the ledger, but it's just a simulation. It will not be executed at this moment. So the next step is that these atomic read writes this. Atomic transactions will be sent back to the client.

B

Client sends this to the ordering service ordering service puts into the block uh into a block, and then basically, this block sends back or will be, will be sent back to the peers and peer basically are checks again if everything is valid and if everything is valid. Basically, it writes to the ledger so from a privacy perspective.

B

What's what's important to know that that's that's a multi-phase uh transaction and the first phase is like having a simulation having like atomic reads rights.

B

Basically, uh that will be actually uh written into the ledger as well and at the end there's some state change, but not just this change I mean the whole ledger is more complicated than having just the stage state change at the end. um We're gonna see like couch. They be basically there's a word state. So the last last knowledge of the word, the last state of the world, can be usually written in a couch debbie.

B

Basically, uh so that's the that's our last uh last word state basically, uh and basically the the the transactions of the ledger are resides. This word, steady, sensed it uh and it's written in the culture.

A

So that's the fabric, physical architecture and it's important in terms of the of the consensus mechanism.

A

B

Me just cover the first, probably well-known uh privacy concept, that's general, so in hyperledger fabric we got something as a logical architecture as well uh or I would say it's a logical architecture and it looks that way uh we got organizations.

B

um Organizations can be distinguished into or can be, can be covered from two directions. um One direction is uh if we have like you know from a modeling perspective from a modeling directions. We say that this is a consortium blockchain network, so basically what we got here. Organizations or enterprises try to collaborate with each other. uh Somehow so in this sense, in this, in this logical perspective, organization is an organization. It's it's a company, it's an enterprise uh that won't once somehow communicate with other enterprises with other.

A

uh Organizations.

A

B

Our technical perspective organization is a is a set of access rules.

B

So basically, if you want to access somehow uh to the whole blockchain application to the whole blockchain network, then you can do it through basically an organization and for the first round or for the first level organizations uh makes already should make you sure that you can access actually uh uh for this, for this whole whole network uh somehow so this is both basically a logical and more like axis perspective, uh but nevertheless we got like organizations uh wanting to cooperate with each other.

A

So the first uh first privacy structure is channel.

B

Channel is a blockchain, uh so channel is the ledger itself. It's the physical ledger. So it's like you know like the blocks uh like the transactions and stuff like that, and the idea is behind hyperledger fabric that, uh with the same.

A

B

You can have more than one blockchains very simple, so one channel is one blockchain: it's a physical ledger. It's a physical blockchain and in our scanario we got like four organizations uh having won. Basically one big uh high volatile, uh I'm just slowing down, because I think my network was a little bit unstable, uh but basically so it looks that way. We got four organizations and one big high pillager fabric enterprise architecture or enterprise infrastructure, and with this architecture we can have modem on blockchains uh very simple.

B

So we got here like channel one channel. One is a blockchain that connects like three organizations.

A

Organization, one organization, two.

B

And organization, free and again, this is a totally separated, blockchain uh all the blocks or the word state all the facts. All the data is replicated just between these three organizations uh organization, for we will not see anything uh basically from channel one. So we got here channel two as well. Channel two is again a totally separated blockchain uh it. It connects organization, two and organization four, so basically all the blocks, uh all the transactions and your full blockchain is replicated just beat between organization, two and organization.

B

Four, um you can have, I mean, theoretically, I'm not quite sure, what's limit, but theoretically you can have as many organizations and as many channels as you want in your setup. So basically, the first level of of your privacy consideration and basically the simplest one is just having organizations and physically separated blockchains between your organizations that we call as genus and again so, basically, that's the best privacy way. uh I would say, because I mean, if, like in organization four uh organization, four doesn't simply doesn't get physically. The data.

A

From channel one, so so this so.

B

Actually, the data is not there, it can't be seen. um There's no, like you know, cryptographic, magic or anything. It's just simply. The data is not there.

B

So what you can do for the first run, if you channel, if you, if you design a hyperledger fabric, uh cooperation or enterprise network, is that you just you- should just basically separate your use cases and separate your channels and yeah in a little bit fancy way. We can. We can say that what you can do is like uh it's like a multi-component sharding mechanism here uh separating your business logic into different, physically different blockchains.

B

uh That might be even connected a little bit with it with each other.

B

So uh if you want to connect like channels uh differentiators what you can do, uh there's this chain code- I mean chain code- is related like for channels, but basically chain code works that the that, with that works, that way that you can have like. Like multi-channel, I mean not multi-channel chain code, but basically one chain code can access to another channel as well. If you have, I mean there are some limitations for that, uh but basically you can change that access is like data from from another channel as well.

B

That's one way uh the other way is like if you have like client logic. So usually you don't have just the blockchain, but you have some like data access, layer or client um that one want basically to access your network. This client actually can connect to channels. uh You know in a pretty easy way, so that's that's uh that's another option uh of using it.

B

So the simplest way and- and I would say the most standard way- is to separate.

A

Privacy in your.

B

In your hyperledger enterprise setup is to use different channels uh separating physically your data. So that's the simplest way. The next way is the so-called private data collection and private data collection gets a little bit tricky. So if you say private data collections, we are in one in one channel. So basically we speak about like one one channel. It's it's one blockchain and what we can do. We can write in data to the public ledger to the to the general.

B

uh That's the public data and we can have something as private data, so private data works. That way. As you can see here, we got some some private data uh that we don't want to reveal for for everybody, and basically this private data is not written into the ledger. Only the heck of the data is written into the ledger.

B

So, basically, if we have like private data, um it's like an an off chain database. What we have it's actually not exactly option database, because I mean the major point is: is that this? This structure is part of hyperledger fabric, so you have basically the same access rights, access structure and different infrastructure considerations.

B

As for any other parts of hyperledger fabrics, so it's not a separated, totally separated concept, but it's in the system, but basically in the system you get like, I would say, an offline off-chain database uh that stores data in a way that only hashes of your data is starting in the ledger and basically uh we get one more mechanism, uh that's a gossip network. uh So it looks that way.

B

If we have like two organizations uh wanting to share basically private data, then there's a gossip network and we can configure in a way that this data is accessible for these two organizations.

A

Okay, so let me just draw actually a picture uh so.

B

The usual setup looks somehow that way that we get like four organizations.

A

So this is like or one this is like.

A

This is like org3 and.

B

This is like org4 and basically these organizations uh realize this one ledger: what one channel. So this is like one channel.

B

And this is one physical blockchain, but we can basically set up, like private data collection, in a way that private data collection shares data just between organization, 2 and organization 3, which means basically uh that this private data- I can say it's- it's private state in a sense- uh can be found basically between organization, two and organization. Three of the hash of the data is written into the ledger. So this is your ledger.

B

So, basically, in the channel in the ledger, you can find the hash of the data of both organization two and three, uh but the data itself can be found just in organization two and organization free and there's, basically a separate gossip network that replicates this data.

B

So your your infrastructure makes sure that your private data is synchronized between o2 and or free. But basically just all 203 sees the private data one and of all four organizations uh they see just the hashes in the blockchain. So that's private data collection, basically.

A

uh So there's couple of like.

B

Catches uh that you should that you should pay attention actually, if you use private data collection so for the first run. uh Basically, it looks that way. If you have a data- and you view write it to uh or you use it with a private data collection, as I mentioned, only hash is.

A

Written into the ledger, but the point is that this this.

B

Hash is not sorted, is there's no no answer or something. So basically, if you just use private data collection in the naive way, then it is so it can be attacked with dictionary attack. So just imagine this situation in this situation. We got like o3 and o2. Basically, uh and only hash of the data is written into the ledger, so basically organization, one and organization four will not see actually the the data itself.

B

uh However organization one and the organization four can basically see the hash of this data and, as basically, this hash is not is not sorted. What you can do is to have a dictionary attack which looks that way. So let me just imagine this situation we got here. In this example, we got a name. That's like john uh we've write john into the ledger.

A

I just have here one uh one: she hash algorithm so.

B

Basically, this is john, and this is the hash.

A

What can be seen in the lecture so in this example.

B

Basically, organization, one and organization four can see only this kind of hash here. Sorry, this one so basically based on this hash, it's not easy to. I mean it's theoretically not possible to to have some hints uh what's behind, but the point is basically, you can do a dictionary. A traditionally attack looks that way. uh You can iterate all of the possible names.

B

So you know like uh basically the names are throughout the words like there are, like I don't know, one million possible names, uh so you can see george, uh let's be count, basically the hash of george. Let me take a look if we see basically this hash here in the ledger and if not that we just have the next possible name.

A

The next first name is, I don't know daniel.

B

So daniel is the is the next possible hash. Let me take a look that we see as organization one like this session. The ledger. It's not and let me just iterate further and let me see hey john basically, and let me just take a look if the the hash of john is something similar, um then organization, one can take a look uh if it sees basically the same mesh in the ledger and if so, then, there's.

A

The a match so basically organization.

B

One can conclude that the data in the private data collection is john. uh Despite it doesn't know uh it just iterated all of the possible names, for instance, uh which is not so many. So it's it's like a couple of million. uh You can find dictionaries with that and based on that iteration, it can conclude. What's exactly in the private data collection, without knowing the exact data.

B

So let me just uh let me just cover basically.

A

So let me just finish up.

B

So basically I mean the solution is, don't use just uh basically uh so never use anything.

B

Just a simple data in the private data collection uh have something obvious, as you know, or sold somewhere, uh because otherwise it won't work.

A

So the question is one field in the private data correction or just one for.

B

The fields in the private data collection, so that's a.

A

Good question, so usually what we do is we write like.

B

Json's into the ledger, so basically it looks that way.

A

I should investigate basically that we get an id.

B

And for this id there's a complex, json and complex json actually has more than one fields and then in this scanner you then, basically one hash is calculated uh on that. So it looks that way in the ledger.

B

You can write like ids and basically and basically value for the ids and I think for each each value for each id there's a there's a hash calculated, but usually, though, you don't write like individual items, uh basically into your ledger, but this is like you know like a complex json having like multiply fields, and it's not a complicated way to have like here, one one, nonce.

A

So in this use case, what's the advantage of private data we're creating a channel? uh So that's a good question.

B

I I should think it over exactly the answer uh in some in some use cases uh there are like you know, I'm the ideas that uh that basically so there should be. There should be a lot of things uh going on on that channel.

B

uh So, like there's, like you know, five use cases uh and five use cases looks that way that all of the participants should see that five five use case, uh and the sixth use case is something which is you know.

A

B

I mean it's not for the not for the general public, just for like the two organizations, and this use case might be even connected with the uh with the other five use cases uh that can be seen forever for everybody. So in that scenario it's it's not practical to to realize it with the channel. uh It's usually much better, basically uh with the private data collection.

B

uh That's one thing, the second thing uh which might be considered uh so I'm I'm not a basically I'm, not a gdpr expert, uh but one idea of like using gdpr or solving gdpr problems uh is that you use basically line private data collections because in private data collection, uh if you, if you delete the name, uh I mean, if you have nonsend the name, then basically only the hash remains in your ledger.

B

So, like uh the deleting there's, there's even a mechanism that you can, I mean this private data can be purged automatically as well. uh But if this private data is purged, then then the data is not anymore in the ledger and if you use it a bit like nonsense, sort and only the hash remains in the ledger, which can can't be so based on this.

B

On this test, you.

A

Can't conclude.

B

Or what's exactly the name, then it might be a good way for like gdpr compliance. uh This is this is a technical infrastructure, that's uh or technical solution uh that might solve gdpr uh problems, uh I'm a technical guy, so I'm not a lawyer, so so speak with the gdpr lawyer. If you want to realize uh such an idea, but but basically it can be an idea actually for for such a use, cases.

A

Okay, so that's one thing uh in terms of private data collection, that's basically nonce! So there's a second problem and the second problem.

B

Looks that way that basically sleep that.

A

Ledger the ledger looks that way.

A

So usually it's like you know, I mean this, is your blockchain.

A

You got some some transactions and at.

B

The end of the transactions, uh you have the state, uh I think in ethereum, like you have the state overall, but basically in hyperledger fabric, you have the straight state that just at the end, so your state is basically deflects the information. The your word state. Your replication word state that you want to that. You want to use actually in your application, but these are the transactions.

B

These are your blocks and basically uh you should be aware that not just the state is written, not just the word state is written into the ledger, but your transactions as well.

B

So the problem is that your transaction mimics, pretty much the I mean this whole fabric, consensus.

A

That we were talking about.

B

That I mean the first part is basically something which is which is a transaction proposal, so you send the transaction proposal uh basically to your peers. uh It simulates your your proposal. It gives back like atomic rights and reits, and these atomic rights and leads are basically endorsed by different organizations.

B

So, what's important is basically uh even if you have like, like private data, so you don't store you don't store at the end. Anything in your words.

A

You can actually a.

B

Problem that you, the despite you, send this private information, basically in your in your transaction proposal, so it looks that way. uh Let me just imagine I have one private data that should be kept somehow confidential. So basically I have this private data. I don't write it into the ledger, but I write it into a private data collection, uh for instance, but the.

A

Problem is, uh if I, coincidentally, send this data.

B

In my transaction proposal or if it can be concluded somehow based on the atomic rights and reads, then I will have a problem, uh because these transactions are.

A

B

The ledger as well.

A

Okay, so for this stuff.

B

There's actually one idea which is called transient field, and it looks that way you should pay attention. Basically, uh if you send.

A

Something in your transaction proposal in a normal way.

B

Then it will be recorded in the ledger. If you use, however, like transient field, then then it won't be recorded. So if you have like one private data that you want to be sure it's private, uh then you should be pay attention that it should be send it with a transient feel.

B

Basically, so then it will be private in terms of like private data, and it will not be seen in your ledger uh either, and then you can have some analysis as well, because it looks that way if you have like atomic rights and reads so usually with your private data collection, you have atomic rights and reads just for your hashes, uh but despite if you are, if you have some some errors, coincidentally, you might as well write some information uh in a way uh that it can be reflected with atomic rights and leads, and there might be a possibility to somehow make some connection with your information that you want to hide.

A

So that's transient field, uh so this is the next picture.

B

For transient field, so, if you use like transient field, uh it's basically, you create your transaction proposal in a way that, instead of standard cause, you use transient field and what's important, is- is that this transient data will not be recorded in the into the ledger.

B

A

Prepared some demonstration as well, so let me just take a look uh if I have some some practices.

A

So what I'm having here is a very simple example. This is like a one organization, art test, so I have like the meantime. I just started because it takes a while, but basically what I have here.

A

It's a very simple organization.

A

It's like one, pier.

A

One ordering service.

A

Hyperelectric explorer it has actually two parts, it has a database and basically explorer and I got set up basically. So this is my setup.

A

That's a container.

B

uh Which helps actually setting up the whole network and I get one more setup. Basically.

A

uh That's for identity mixer, but it doesn't matter at the moment and basically it looks that way. I got like one organization um so.

B

This is the simplest demonstration.

A

That can be imagined uh for such for such scenarios and it starts. It will take a while.

A

It's like two more minutes.

B

So in the meantime perhaps I just show the uh the code. I prepared some very, very simple code.

A

That you can see here and that's what we're gonna take a look on.

B

So I have basically one smart contract one chain code. uh It has, for the first run, save data uh save data, it's a very simple save we just we just put put information into the ledger, so I get just one id id and one some some information and.

A

I just put this to the ledger. uh I have.

B

That as well, it really sold the information from the ledger it's like gets did so. The next version is save private data and get private data. uh It looks that way. I use private data, uh so I have like two more calls. One is like put private data. I just write private data to the ledger. It's basically there's a test collection uh in which I write this information and I get like get private data. I just read out uh information from the from this from the same private data collection.

B

uh Anyway, private data collection is basically described with the help of a of a json that must be actually configured uh during the setup of the network. I mean at the installation of your.

A

Chain code, so it's again it's a very simple private data collection uh and I have a third call pair as well. It looks that way I have just.

B

The same private data save and read out, but I use basically private data collection, sorry, private data collection with transient data. So it looks that way. uh In this scenario, I have private data. I have saved the private data and basically I have both my id and my data in the transaction itself and if I take a look with like save.

A

Private data with transient.

B

Then it looks that way that I have just the id in the transaction itself and basically my transient data I mean: can we get actually with a separate call, so basically the data itself, I mean the private data itself will be read out uh in a different way and that will be sent actually uh with help of a transient field. Basically,.

A

So these are my functions and theoretically my network should be ready and then basically.

B

A

Hyperledger explorer as well, you can't see everything on hyperledger explorer, but you can see a couple of things and I think it's admin.

A

And if I find my password, I'm pretty lucky: okay, awesome, so that works. So I got a network up and running. So let me take a look. What I can here do- and the first example is looks that way.

A

I will have basically a very simple transaction: uh that's a normal transaction! So what I'm gonna do here.

B

I have basically a setup container need to have a cli setup container. I just have I just save my data. uh This save data is the is the name of the transaction. It is actually the name of the of the chain code and I have just one id and one data. One basically, and I mean in this sense data one will be on the long run, something which should be considered as private. It's not private. At the moment. With this setup, I just save the data id1, and I just save this data into the ledger.

A

So let me just have this command.

A

So it was successful.

A

So if you just take room basic, take a look actually uh with like explorer, we can see actually a lot of information, so this is the transaction.

B

Details of hyperledger explorer- and actually it sees some some relevant information, like perhaps what's important, it can be seen which organization created has created this transaction, who endorsed this transact transaction um some time, information and basically the atomic rights and reits are here as well.

B

So, basically, you can see at the bottom that basically there was some id1 key and there you want data. So this is not the transaction. This is the atomic revised set up. That can be seen basically on the ledger, so this information is visible with with hyperledger fabric, with hyperledger explorer, even thai pleasure explorer.

A

So let me just take a look. The next one and the next one is basically a private data transaction. So what I'm gonna do is that basically.

B

I call this safe. Private data function, save private data function again. That looks that way. So, basically, I have here nothing. uh Just I use, instead of putting data into the ledger like putting data into a private data collection which is configured here.

A

B

If I see private data, then basically it looks that way. I use similarly, this id1 and I use similarly basically a data which is which is private data. One.

A

So if I have this stuff.

A

Let me just execute this transaction.

A

And if I take a look and typological export app, it should be the top transaction so that.

B

Should actually look better hyperledger.

A

Explorer doesn't really show uh much about my my my.

B

Private data- uh basically uh I can, despite take a look, my my private data. If I want.

A

If I have the correct organization, what I can do is that I can take a look on my on my coach db, just a second that should be.

A

That should be there's an administrator console for coach db and you can call it with underline uts if I'm not mistaken,.

A

Yeah, that looks great, I'm not quite sure. What's my username and password.

A

A

Then it works. So what I see here, I see some.

B

Databases, it's like this is the database of my of my development channel this test channel and I can see actually here the id1, uh the id1 that was written into my channel. Actually in the with the first transaction I get.

A

Somewhere, actually perhaps you attachments, if I say like view attachment, then I see you can even see.

B

The data as well, so this is data one. I wrote data one into the ledger with my standard transaction.

A

And what I can see here is, I have my private data.

B

As well, it's again it's just one organization. So basically I should see my private data. uh This one is this dev channel test private data, and this one is the id2. If I'm not mistaken,.

A

uh I think that was like id2, but let me just check it. No, it's id1.

B

And that should be like private data one so basically.

A

If I just have id one and private data one then I should see here private.

B

Data one, so it looks good um again I configured in a way that I see my private data actually in my organization, but if I, coincidentally, don't have access uh for the private data that I won't see. This information here.

A

Okay, so what I can do.

B

I mean this is the classical way of like checking the information, but basically, what I prepared is some deep level analysis of the ledger itself and.

A

It's getting tricky here a little bit so what I have.

B

Here so basically it looks that way that your ledger is not encrypted, so every information uh that that is on the ledger can be found on your peer. So if you have access for your peer and if you coincidentally know how to encode your information, it's again it's encoding. So it's like like unicode or ask your stuff like that. uh It's not so easy, but it's not encrypted.

B

So technically you can enter encode your information from your ledger and you can see basically everything um what I'm gonna do is not the deep level analysis of the of the ledger itself, but there's.

A

An administrator function, that's an administrator.

B

A smart contract that you can call- and that has a core basically get transaction by id, and what I can do with this call is, is to get one section from my ledger, so I will get the whole transaction from from from my ledger. So.

A

Let me have uh this was actually the first uh transaction, so let me just go actually into this javascript file and if I'm not mistaken,.

A

Okay, let me just try it.

A

B

Is basically our transaction? uh It looks that way that the I mean the encoding is tricky a little bit. uh I got here several versions, it's like once. I I convert a little bit like to s key, then to to base 64 and so on. So the the the encoding is not necessarily the simplest, uh but nevertheless it can be done. So it's it's not there's no key like for encryption or something it's just an encoding.

A

So this is my transaction, it is encoded somehow and if I just put it to the integers on.

A

Viewer then I can.

B

Deep level analyze.

A

Basically, uh my transaction, so let me just let do just how can I clear it? I think this one. Let me open the other one.

A

Let me just give a shot with this one.

A

Exactly so here we are, uh this is our transaction uh and it looks that.

B

Way uh so we got some signature at the beginning, uh then we got.

A

Some payload some header, uh some some channel information, a lot of things.

A

But if we just go down, there's.

B

This signature header so like one thing, that's important to know, uh there's this creator, um you still remember. If you just go here, we can see the creator membership service provider of our transaction, but actually the situation is a little bit more problematic, because if we get the transaction we don't only see the membership service provider, but we will see actually the the whole x 509 certificate that created and signed our transaction. So this is like actually the.

A

Orex 5.9 certificate uh for the formulator.

B

One thing that's important: we got here like so if you, if you just created our certificate for somebody, it's just an administrator, but if we have like names here like uh we create a uh you know, we create a x509 certificate to a certain name. Then it might be a little bit problematic because this name, this common name, is written into the ledger. So it can't be deleted. So if you have like some gdpr considerations,.

A

It's not necessarily the best idea and in the.

B

Data field we see basically the read, write, sets so again. It's creator.

A

Again, creator information again, so we got here. Actually the issuer, that's just the certificate authority, but here again.

B

We got the common name for x 509 certificate, which might be pretty much unpractical, but somewhere we got the chain code proposal, so we should basically see.

A

Our first uh whole proposal here so.

B

If we just take a look, this is our proposal. That's that's how we call the transaction. It's safe data, it's id one and it's data one. So pretty simple!.

A

Okay- and we get some endorsement as well, but personal endorsement is not so complicated or not so problematic, but problematic uh is.

B

The is the read write sets, so we should see somewhere not just.

A

The not just the already original uh proposal.

B

But basically the whole read write sets as well.

A

I'm not quite sure if I find it, but that should be somewhere here. Let's paint all the chain proposal responses.

B

Basically, or can be seen like uh like with.

A

uh With explorer as well, some don't know if I find it exactly yet, because this is the one and we find.

B

Here the read right sets and we see here the rights- and we see here that we have id1 and we got data one.

A

Okay, but this is totally normal and it's totally normal because that's a normal transaction, but let me just let me just go back and take a look, my second transaction.

A

I think that was my second transaction, but I mean I can just execute once again. So basically, I just execute my transaction to a private data.

A

So this is my private data transaction.

A

I just execute it again. I got a new transaction id and basically, what I'm having I just try to deep level analyze. This transaction.

A

So it looks a little bit like weird, but.

A

If I just have this new version.

A

There should be some information in there, which is not so practical.

A

And it's again, it's not always the simplest to find, but so this is like the chain called proposal payload, and I should find here the proposal and.

B

Basically, it's we can see. This is the proposal. So again, uh this is a proposal that was sent actually to the blockchain. As for endorsement- and we see here the safe private data- that's the function name and we see here the id1 and we see here the private data as well. So this is something that should not be recorded actually in the ledger display. That's for sure.

A

And the other one is what's perhaps important is that in the action we can even find the hashes itself. It's not so.

B

A

Get but basically we got the read, write sets and we have somewhere collection of hash d.

B

A

Sets so basically.

A

This is hash rights, and this.

B

Is the hash key, and this is the hash data, so I will not demonstrate this uh due to basically uh time constraints, but basically based on these hashes. This is the uh ssh hash of your data, so based on without any nonce noise, or anything like that. So, based on this hashtag, you can have something as a dictionary attack and if you're lucky, you can find. Basically the the original data, uh pretty simple.

A

So I got my last transaction and my last transaction looks that way here. Basically,.

B

I use transient field so it looks that way. uh I use. I set up some some test transient data and basically I call this function in a way that there's there's transient data.

A

So let me just show this one as well.

A

And let me show this transaction.

A

So basically I got my transaction id.

A

So again it looks a little bit like nasty, but.

B

Just a quick check.

A

B

I just go to viewer.

A

So what's better or what must be better.

A

Is that I shouldn't see the data as I, as I just call the function, so this is the chain called proposal payload and basically, what I'm having here is that exactly.

B

So I have here the safe private data transient, that's the that's the function, call that's the chain code function call, and I have here the id2 and what I'm not having here is basically this. uh This data, uh which is which is basically actually I mean this one, is the data um it's a key value pair. So basically I have the key data and I have some some data, which is the message itself and basically, as you see it,.

A

Is not recorded in the ledger uh so because it was used like in in transient data field. So I just like.

B

These two pieces of information- uh and I mean the rest- is pretty similar uh because I just write into the to the private data collection. uh We don't like having to consider like, like salt or not.

A

Okay, so basically, uh this is like the first part of the presentation.

B

uh If you use like trans uh use, like private data collection, uh just just consider using nonce and consider using transient field.

A

What there's a third important point as well, are that still with private data collection,.

B

And the third one is like something which is endorsement.

A

And endorsement looks that way. So if you have like organization.

A

It's like all one and you get like organization two.

B

And if you consider private data collection just for one organization, but you have a transaction which you send for both organizations for endorsement, uh then there's usually some tricky behavior as well. So you would expect that if you send this transaction to both organization and this it has something to do with like private data, which is configured only only at organization two, then then the transaction will be fed. I mean I mean you get an endorsement failure, uh but this is not usu, always the case uh in normal, accepting, theoretically and.

A

It's for some reasons, it's basically a general setting or it's a.

B

Normal setting or considers as normal setting with hyperledger fabric, if you, if you just write the if you just want to write uh this private data collection, uh then if you send this transaction for endorsement uh for both organization and this organization, one doesn't have basically the private data. It doesn't cause errors, so it doesn't cause failures. So this part, if you just want to write a new value, for instance in your private data collection, your transaction will be endorsed uh actually by by both organizations.

B

So this is like a feature theoretically, but nevertheless uh it might cause problems, because I mean, if you consider you put some private data into your transaction uh either as a transient field or as a normal.

A

Field uh but you send it for both organization, then basically.

B

This organization gets private data, uh even if, even if it doesn't have private data collection- and even it shouldn't get this private data collection, this private data, so you should pay attention on the endorsement strategy as well. It feels like private data collection and the reason is for that, because the endorsement works in a little bit like like clicky way, so your transaction might be endorsed, even if there's no private data collection configured with that organization, which means that your private data might leak. Nevertheless, so that's the circle.

A

Self configuration- and I would just stop here for a second- I.

B

Have a couple of more slides, but I'm not quite sure how long did we did we planned this uh this this session? This scenario.

A

So I would just stop here and and open a little bit like uh questions and answers, uh and I would just ask as well if.

B

If I just cover some more more slides as well.

A

Foreign, so is there any questions.

A

B

I'm not quite sure I mean you could use. Basically, this chat as well.

A

uh If you have like questions.

B

So uh if there's one more question uh again, I'm not quite sure I have like two versions and in one version my presentation is one and a half hour long and the other one is just one hour, so I will just continue with a couple of more slides. uh I hope it's okay uh again.

A

I wasn't sure if, if I should plan one hour or one and a half, but nevertheless let me just continue and the next I I got like two more concepts. Basically, uh uh these these or three more concepts. I would just summarize these concepts as well.

B

uh This is again basically uh it's a usage of frenzy and field. If you know in a case, if you, if you don't want to use the private data collection, so usually use transient field bit private data collection. But this is not the not the only one, only application area, so it looks that way, there's a pattern which is not much used, uh but but nevertheless it exists and it's transient field and encryption, and it looks that way. So if you want to have like privacy, you can make like like ledger.

B

uh Ledger encryption, uh hyperledger fabric doesn't doesn't support uh encryption in your ledger, so you should actually implement it on your own. It's it's completely up to.

A

You, and so it's actually it's tricky so so the the general idea.

B

Is that don't use ledger encryption unless, unless you do what you do or unless you know what you do, otherwise it might be a little bit tricky and then you can imagine basically uh so ledger level. Encryption means that all of your ledger is encrypted. um You get some some keys for encrypting and deep, deep clip crypting your information and it is completely handled by you uh and then fabric has some minimal support for that, but but not not many examples throughout the world how it can be used.

B

So if you have such a pattern, one thing which is tricky uh is basically is that you want to. You want to have actually uh something which is which is business logic. So, in your chain code there's a business logic, there are transactions, and if you, if you want these transactions processed on your ledger, then that's not such an easy thing, um because I mean the point: is that your business logic, your chain code, should work basically with encrypted information, so there are like two ways how you can do it uh or two big directions?

B

One. The big direction is the is the cryptographic way uh it's pretty complicated. It's you know, I mean the idea is how you can process uh actually uh information uh uh in a way that they are encrypted so like how how you can process encrypted information and it functions. It's.

A

Like uh homomorphic encryption and functional encryption and stuff like that, so it's it's pretty much.

B

Cryptographic heavy uh the other one is that you can use, is kind of an architecture trick of the hyperledger fabric, and basically it looks that way you use like the transient field. um So this is your chain code, uh and this is your ledger.

A

It can't be very much seen because of the chat, but I just put the chat below and we got here the ledger and the point.

B

Is that, basically, that all of your information is encrypted in your ledger? So.

A

Your chain could want to know what to do reading for me because it's encrypted, but what you can do is that this is a user uh sending a transaction that should be.

B

Somehow processed with your chain code, so what you can do is that you send the decryption key are in your fabric, transaction in a transient field, then chain code gets basically this decryption key. It reads out the encrypted information from the ledger. With the help of this of this decryption or encryption key, it encrypts or it decrypts the information.

B

It's it it processes. Basically, this information, it encrypts it again and writes back to the ledger, and in this way you can have.

A

As as many or as much.

B

Business process with your chain code, as you want, despite the information in your ledger, uh remains actually encrypted. Certainly, there's one catch one catch is that your encryption key is here, so you make sure you have to make sure that this encryption key won't be leaked. uh It's like won't be linked uh basically uh through with your network, and won't be linked with your with your chain code container, so it might be tricky. I don't know how it can be solved with network.

B

It's like if you may want to make sure that this encryption key won't work, won't leak with your container. You should use something as a trusted execution environment, which is again pretty pretty tricky, but this was just an example that you can use transient field without without a private data collection as well.

B

A

One one other privacy uh structure.

B

From hyperledger fabric and that's identity mixer, so, as you still see, the problem is basically.

A

With with such uh with such a transaction that this is your transaction, and I briefly showed that it looks that way that.

B

Actually, the creator information can be found here.

A

Which might be not the best idea, so normally, if you use like x509 certificates,.

B

The problem is that your horse certificate is written to the ledger, so you have here like again, this is administrator, but if you like just configure you know, I mean I mean one: one certificate one client side certificate easter for each of your users, then, basically, each of your users, each of your users, will appear in the ledger based on this x 509 certificate.

B

So one way of finding this information is that, instead of x, 509 certificate, you can use something: that's identity, mixer, it's um it's! It's actually a cryptographic, uh xc structure, but it's not based on a public private key cryptography, but on verifiable credentials and zero knowledge proof. So, basically, this is the idea. I won't go very much into the details you get like issuers issuing credentials.

B

You get some some proof, uh basically uh on your credentials that you show for a verifier and basically use some some zero knowledge tricks here. So not all of your or all of your attributes are revealed.

B

So it looks that way what you can do with item x uh is basically.

A

To hide this information.

B

So it looks that way you will have. Basically the uh you will have basically the uh some some properties that are revealed uh like the like the uh like the organization where you need to add it all is really, but basically the enrollment id is hidden. So this one is that you're, the I don't know admin one of the xyz organization. This information can be actually hidden uh with the help of identity, mixer and perhaps in the long run there will be other properties that can be hidden as well. So it's important to.

A

Know that the idea of.

B

Cell is to hide this piece of information as much as possible in your ledger and your signatures. Unfortunately, identity mixer has some some limitations uh and then so let me put it that way. It was heavily investigated like a couple of years ago, but nowadays I'm.

A

I'm not quite sure it seems, but it's just my.

B

You know idea, it seems it's, it's not so much heavily further developed. So the point.

A

Is uh first, you can have just.

B

Organizational uh and organizational client certificates this way, so you can't you can't have something as an endorsement. Basically.

A

You can't you can do endorsement.

B

There's a fixed set of attributes, it's like there's, you can have an organizational unit or all these are revealed and you can have basically one enrollment id that can be hidden and basically revocation handle, but it's it's not and then, according to the documentation, there's no official revocation.

B

So if you want to do revocation, it might be tricky as well. So again this is identity mixer and the idea is basically to hide some piece of information who created uh this. uh This.

A

B

A

uh Transaction.

B

But basically with having the cryptographic guarantee and and stuff uh for the for the whole hyperledger fabric structure,.

A

I have one example here as well for identity mixer transaction, so it looks that way if you want to configure identity mixer. I had one example on the net.

B

And it looks that way that I I created a special organization called.

A

Organization, one itemix and basically it's starting the whole network and there's a tool which might not be used for production. uh But that's an itemix.

B

Generator and with the help of an itemx generator, you can create a couple of items to make sure certificates and basically I have this organization just for the identity. Mixer configured with the generated.

A

Identity, mixer certificates and the point is that this organization won't have any beers.

B

It's just a plastic organization to start basically uh transactions with. uh So basically my my channel and application policies are set up in a way as well, but basically, uh basically this uh this special itemix organization won't matter, so it won't do like endorsement or life cycle endorsement or stuff like that.

A

So having this example, I can show one edamix transaction as well, and.

B

It again it looks that way. I configured basically one special cli.

A

Once you see a light just for identity mixed and it's pretty similar as a standard cli, uh the difference is that I have to use.

B

Like core peer local membership service type, it's side mix, uh I have the local msp id uh for the for the itemx certification as well, and basically what I'm having in the msp config pass. I have my my edamix certificates, basically and.

A

Having this, uh basically, I can create one transaction.

B

It's pretty much the same, so I have invoked or I invoke one transaction uh with like in.

A

The classical way I just.

B

Via basically, a cli uh cli, itemix container.

A

So if I do it, let me just change back actually to explorer what I will see.

B

A

B

This is my: this is my transaction and, as you see basically, hyperledger explorer won't always recognize this identity, mixer transactions.

A

I don't know why, but if I just take a look in details on this transaction.

A

uh It's getting more freaky.

A

I hope it works.

A

A

Yeah, that should be great.

A

So if we take a look on this transaction.

A

Then the difference is that so in the in like in the creator, there should be like lasting formation.

A

And perhaps you can see it so if you can see in.

B

The creator, uh we don't see the x 509 certificate anymore. uh We just see this is theoretically kind of a zero knowledge proof. uh I can't I can't decode it more. Basically, uh but theoretically it reflects like the right like the role and organization you need, but it shouldn't reflect like the like the exact exact person, or is the exact exact name of the certificate that created this transaction.

A

But nevertheless, like I mean the rest, is, is unchanged so, like uh you can't use for endorsements, so like uh endorser is pretty much. The same still use these text. Five online certificates, so that's identity, mixer, and my last slide for today is that we got some advanced patterns uh based on the previous uh previous uh uh ideas so like uh with.

B

The help of of like different usage of of private data collection, uh transient field uh and edemics, even uh you can have some some pretty good things. uh It's like one pattern goes into the direction. Is that how you can coordinate like two organizations in a way that they they exchange information, but this information won't be won't, be visible for for other organizations, even if they are on the same channel, even if they see everything on the on the channel. Another idea is basically something which is, I would say, it's a quasi-only endorsement.

B

uh It's pretty tricky, so basically, endorsement is visible on the ledger. So, if you just want to endorse the transaction with two organizations, then you will see on the ledger that this transaction was actually endorsed by these two organizations, uh which.

A

Might be not so optimal uh in certain use cases, so you.

B

Can have something uh which is similar to.

A

A seldom or endorsement it works.

B

That way, it consists two transactions, uh there's a pre-approved and there's. Basically an approve and pre-approved looks that way. It writes some some information in the private data collection of the organization, one uh I didn't mention, but basically every organization has has one special private data collection, which is just for the given organization.

B

So I can write some some information in this private data collection like the like the metadata of my transaction or that should be approved uh on.

A

The long term and then having this pre-approved.

B

uh I can send basically a transaction to another organization which is just endorsed by organization two, and I can send this this. Actually, this private data.

A

In a transient field and.

B

With this approved transaction, the other organization can take a look. uh If this I mean, based on the hash, can take a look if this information, if this transaction was really pre-approved by by one organization, there's like a third advanced pattern as well. It's like uh so as basically, every organization has has a special private data collection, which is just for a certain organization.

B

You can. You can build up uh networks that work in a way that there's there's private data in in for each organization, so your data structure looks that way. You get some public data and some some private data, and then this private data will be moved actually uh with certain transactions.

B

So you can, you can imagine as like, there's a private token just for the organization one and it moves to a private data collection of an organization too. uh If there's a certain transaction basically uh happening.

B

So that was my last slide.

A

B

Basically, uh I would say, question and answers, I'm not quite sure about the timing, but it seems we have already like one and a half hour.

B

Yeah sure, just being me on linkedin, uh if you, if you want to uh yeah sure, uh just bring me.

A

On linguine and and anytime for sure uh yeah, but uh I would say I hope.

B

We have like 10 more minutes, so I would just switch back to like question and answers and.

A

If you have any questions, I'm happy to answer.

B

Yeah sure uh so I will post actually uh both this presentation and basically the the I mean presentation, includes my github repo as well. I will post this uh basically meetup uh and I think we got like live youtube streaming. So usually I post it under the under the live youtube streaming as well, so you will, you will have the link both for the presentation and for the github repo as well.

A

So I don't know uh if there's actually no more question regarding this topic, uh then I would like you. I would like to thank you very much for your attention and I would just slowly actually close this meet up.

B

So last chance, if you have any questions.

A

For for fabric and privacy, uh just let me know.

A

So if no more, then again, thank you very much for your attention and then yeah, I would say, have a nice weekend, but uh it's actually on just thursday so and thank you daniel. This was really helpful, so one one day, one day to work: yeah, yeah, okay, so thank you very much again thanks daniel thanks. Everyone.

A