Hyperledger Foundation Fabric, 11 Jun 2021

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From YouTube: Verifying Transactions in a Hyperledger Fabric Ledger with Blockchain Verifier - Taku Shimosawa

Description

Verifying Transactions in a Hyperledger Fabric Ledger with Blockchain Verifier - Taku Shimosawa, Hitachi, Ltd.

While blockchain provides immutable and trustful data store, enterprise systems often have additional requirements for reliability and auditing. Blockchain Verifier, a project in Hyperledger Labs, is a tool that verifies the basic integrity of blockchain ledgers and also provides a means to write checking logics particular to each blockchain application. The result can be used as evidences for auditing, for instance. Blockchain Verifier is available at https://github.com/hyperledger-labs/blockchain-verifier. This demo presents the capability of Blockchain Verifier to check Hyperledger Fabric ledgers, and how to write a program that performs additional checks to the transaction in the ledgers with some example applications. Taku welcomes any contributions and suggestions for improvement for Blockchain Verifier to be applied to other practical blockchain use cases.
Sessions Details & Slides (if available)- https://sched.co/j3bL

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Hyperledger – Open Source Blockchain Technologies

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Okay, I think it's now time so I'd like to start my presentation, so so hello, everyone, so I'm takshimo sabha from hitachi. So today, I'd like to present the verifying transactions in hyperledger fabric ledger with the blockchain verifier.

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So, first of all, I'd like to start with the why we need a verification in the blockchain ledger, so the one reason would be that compliance to the regulations, so enterprise systems, especially the banking systems, require some auditing that is required by the rules or the loads.

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So, and the second reason would be that the addition adding the some reliability to the smart contracts and blockchain-based systems, so um such kind of the additional checks on the past transactions or the data in the blockchain-based system will include that one is included. The complex checks that need too much time to perform during that execution of the transaction or some checks that need a comparison with external systems.

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What checks the needed? Verification with the other data that became after the transaction transactions are invoked. The third reason would be the detection of faults in the blockchain nodes.

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It is to detect some corruption of data that is caused by some hardware faults or the software bugs that inc that, whether it is uh smart contracts or that broken platforms, so if that could happen um very regularly, the checking the contents of the ledger will detect such corruption and then, and then that we can some do some fix on that correction so that to increase the availability of the blockchain nodes, what a blockchain network, which that the peer is participating in so to do this verification, um we we are developing the tool that is named.

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The blockchain verifier are two to verify the broken ledgers the target uses after these two will include the internal or external auditors.

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What the blockchain network administrators and this these two has the three main functions: one is to verify the integrity of the ledgers and snapshot and compare them with those in the other peers so that it can detect local alteration of the ledgers or some local change or faults that is caused by some force in that blockchain nodes.

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The second function is to allow application specific logic to perform additional checks. I will explain later, but it is to detect bugs or the flows in the smart contract, logics or two allows additional checks required by the regulations, such as the anti-money laundering checks that is required in the banking transferring systems.

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The third is to generate reports for the checks that is performed and the currently that this tool is supporting the hyperledger fabric version 1.4 and the version two points something and it is available at the hyperliteral. It is actually approved as one of the hyperled labs and available at this url.

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So please check out later at this url, okay, and this figure shows the example use case of these two, so in the auditing scene, so the user in this auditor, the audit can be internal internal means that if they are in the in independent section inside some organization- or it can be external, that means that they can be that in external organization, which has some contact with to some particular organization that is participating in the blockchain network, and they can do the um check.

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What a verification using this blockchain verifier um either is a periodically or continuously periodically means that that is. Is in the case in the traditional auditing, the like that, the performing that this kind, these kind of checks in at the end of the quarter or the year or the halfway level, etc.

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But if this blockchain verifies connected to the actually the blockchain network, they can do the checks continuously. That is, that perform. That is that the continuously flowing the transaction that is performed that is invoked in the blockchain network into these two okay.

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So, and this figure shows that the input and output and the checks performed in these two. So the input is obvious. That is a ledger of the blockchain and our output. Is that the verification results or the report?

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That is what checks is performed within either these two and what was the result for the checks and the checks that performed in the blockchain verifier. That includes that for the ones for the blocks or the ones for the transactions.

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So that includes for the blocks, these two. Can this cool this sort, these two checks that the hash values were the signatures or the blocks and the transactions? What are for the transactions?

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It includes that input versions within variants inside the transactions.

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And for the checks that is performed that is performed by the blockchain verifier, the two types, two levels of the checks: one is a platformer level checks and the other is application. Level checks.

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The platform level checks are independent of the applications and common to the specific blockchain platforms.

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So this is this will be the general checks on the immutability and the consistency and the consensus, and it is performed by the private into the blockchain verifier, for example, that the fabric block plugin, as this name shows performance checks for the hypothetical fabric ledgers.

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The second type of the checks is application level checks, so these checks are specific to each application, so this should be written by the application developers and blockchain verifier provides apis to to write the check programs to search to write the search check programs with the application.

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Developers and what properties right should be the checked by this direction verifier, so the properties will be there.

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So these four properties should be the provided by the blockchain platform blockchain systems, and here I showed the immutability and the consensus, and the consistency and correctness and this table shows that which checks will check, will verify the validated properties which properties, for example, the for the immutability.

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These platformable checks, such as hash value, checks on the blocks and transactions and signatures on the blocks and endorsements, and has comparisons with the other peers will make ensure that these that ledger has a dimitability for the consensus. The sign of the check and the policy checks will provide will enjoy the conscious consensus and the versions of the read write set in the transactions in the lectures will enjoy that.

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There's a consistency in that lecture and for the correctness we um actually that the platform river 6 will not provide that correctness because of the the protovoid itself does not know that the weight. What is the correct for the smart contracts or the transactions that is invoked by the prod that are using that smart contracts?

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So the application level checks should write. I should check such kind of properties. In the other words, these three properties will be checked by the platform platform level checks and for the core and the coordinator for the correctness, the application level checks should be checked for these properties, so application level check.

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So these are the, as I said that they are the checklogics that should be the written by the application developers.

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But what checks should this logic should perform?

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So, let's show some example: one is to run another logic that is equivalent to the smart contract, so this will ensure that that the smart contract is correct by the compiler, comparing the result that is edited by that another implementation, that is, that making sure that the correctness by the using the diversity in the implementation.

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The second example would be that checking the invariants in the smart contract for the trivial example for the when the money is transferred the transit. The transaction should sorry that the input, the sum of the input for the transaction should be always the sum of just be identical to the sum of the output of the transaction.

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So we create the environment and uh to seeking such kind of invariance, we will ensure that the correctness of the smart contract with the transactions, that is the result of the smart contract and the second would be that the performing additional checks against the external systems and the blockchain verifier provides the fps to access keys and transactions with the circulosics so that they can write this kind perform this kind of checks.

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So I will show that someone example checker a prediction level checker for the fab core, smart contract. Fab core is an example chain code that is in the hyperlithophobic repository. It is to manage their car assets and the two function two main functions in the about fabric: smart contracts. One is a create car that is, that adds a card into the ledger and the ch. The other is the change core owner to change the that is to change the car owner.

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The text to be performed. Then this. um This shows that some checks- that should some example, checks to be performed by this application level check, and so I will show that this, for I highlight this. The second one, the credit card function does not overwrite the existing key. Actually that this is the um there's some bug in the hype.

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Sorry, this chain code and the chenko does not check that if the key already exists or not when creating a new car, so so using it so that using the same id for the new for the new car to that is create a car function will result in that overwriting the old car assets by the new car without any checks.

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So this shows this is some example script that undo the that check. This is written by the typescript and this transaction provided by the blockchain verifier. So this is what the application level check. The developer is expected to write for the application level checks.

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So first it checks when what is the function for this transaction and it gets the right set and it tries to get the value for that.

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The key the same key, that is, the new cars key.

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From that state that is available at the time of the invoke of this invocation of this transaction. If this is successful, that means that there is a key with the same name at the time of this transaction. So this checker will report error.

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That is the failure for this check, so actually that the coding that using the same id for that choose uh solicitor transaction create code functions will be successful, but actually that this should not be successful. So this checkout script will find that this is error, and actually this is a result of that running that running, that this check against the real ledger and it will report this check failed and it will report in the json format- and this includes that which checks are failed in for this ledger.

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Okay, so recently. So this is the just the summary of that. The recent update for these two, that is, to support the fiberless fabric ledger, and it includes some feature to compare the ledges with the multiple ledges before the other peers and we're planning to integrate some more tools.

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That is avail, that is the proposed for the hyperledger fabric and so on, to for the better compatibility with hyperlithophobic ledgers so um again that this tool is available at the hyperlink labs and available at this repository url, and we welcome you any contribution feedback and also you can feel so. Please feel feel free to contact me with using the email or the rocket chat or whatever.

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So thank you very much.

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So I think yeah. I have no question here. So if you have any questions, please yeah contact me in any of these to this yeah contact contact.