Transaction failure only when i am using AES GCM ciphertext (NodeJs)

[eduhenrique]

Hello. I have been facing this problem for almost two weeks => a commit of transaction error with status ENDORSEMENT_POLICY_FAILURE only when i am trying to persist a object with some attribute related to a ciphertext from the crypto library

Basically i am doing this:

`

        ...
    var securedHashToVote = await this.encrypt(hashValue, key);

    const vote : Vote = {
        docType: 'vote',
        candidateNumbers: candidateNumArray,
        electionNum: position.electionNum,
        voterHash: securedHashToVote
    };
   
    var buffer = Buffer.from(JSON.stringify(vote));
    await ctx.stub.putState(hash, buffer);
}

public async encrypt(str: string, key: string)
{
    const cryptoImported = await require('crypto');

    let aesKey = cryptoImported.scryptSync(key, 'blockchain', 32);
    let iv = cryptoImported.randomBytes(12);
    const cipher = cryptoImported.createCipheriv('aes-256-gcm', aesKey, iv);

    var enc = cipher.update(str, 'binary', 'hex');
    enc += cipher.final('hex');
    enc += iv.toString('hex');
    enc += cipher.getAuthTag().toString('hex');

    return enc;
}`

And i am getting this:

`2021-05-29T05:27:59.182Z - warn: [TransactionEventHandler]: strategyFail: commit failure for transaction "7eecf7657a2e3164c08d797db9ff9019f789f753e7bb88a13c6aea7b56a3181e": Error: Commit of transaction 7eecf7657a2e3164c08d797db9ff9019f789f753e7bb88a13c6aea7b56a3181e failed on peer peer0.org1.example.com:7051 with status ENDORSEMENT_POLICY_FAILURE
at TransactionEventHandler.eventCallback (/home/edu/Documentos/eduhenrique/fabric-samples/electoral_process/typescript/node_modules/fabric-network/lib/impl/event/transactioneventhandler.js:84:31)
at CommitListenerSession.notifyListener (/home/edu/Documentos/eduhenrique/fabric-samples/electoral_process/typescript/node_modules/fabric-network/lib/impl/event/commitlistenersession.js:77:18)
at EventListener.callback (/home/edu/Documentos/eduhenrique/fabric-samples/electoral_process/typescript/node_modules/fabric-network/lib/impl/event/commitlistenersession.js:68:18)
at EventListener.onEvent (/home/edu/Documentos/eduhenrique/fabric-samples/electoral_process/typescript/node_modules/fabric-common/lib/EventListener.js:132:10)
at EventService._callTransactionListener (/home/edu/Documentos/eduhenrique/fabric-samples/electoral_process/typescript/node_modules/fabric-common/lib/EventService.js:1019:17)
at EventService._processTxEvents (/home/edu/Documentos/eduhenrique/fabric-samples/electoral_process/typescript/node_modules/fabric-common/lib/EventService.js:985:11)
at ClientDuplexStream.<anonymous> (/home/edu/Documentos/eduhenrique/fabric-samples/electoral_process/typescript/node_modules/fabric-common/lib/EventService.js:462:12)
at ClientDuplexStream.emit (events.js:210:5)
at addChunk (_stream_readable.js:309:12)
at readableAddChunk (_stream_readable.js:290:11)

Failed to submit transaction: Error: Commit of transaction 7eecf7657a2e3164c08d797db9ff9019f789f753e7bb88a13c6aea7b56a3181e failed on peer peer0.org1.example.com:7051 with status ENDORSEMENT_POLICY_FAILURE
`

But, if I create the ciphertext but do not set inside the vote object, i am able to persist. If I receive this ciphertext from a client (submitTransaction) and then set into the vote object, i am also able to persist. But I really dont wanna to do this on the client side.

I am using Hyperledger Fabric 2.1, and I basically just copied the fabcar example, change the name, and start to do some coding on it.

Appreciate any help on this.

[yacovm]

What is the endorsement policy? Does it require at least 2 peers? (in example, org1 and org2)?
Notice that you set a random IV:

let iv = cryptoImported.randomBytes(12);

This would make your ciphertext random.
You can try sending the IV as a chaincode parameter, since the IV is not secret (only the key is).

[eduhenrique]

Uou, thank you man. I understand now..., since the final value was different the endorsement would never be right.
Like, the different results of ciphertext was intended, so I put a optional iv parameter to be used only in this occasions.

You really saved me, i wasn't able to see this issue.