Fabric Aries

This is a design docs for integrating aries with hyperledger fabric blockchain. Doc will be almost common for other general purpose blockchain (like ethereum, solana, hedera hashgraph) which supports smart contracts.

Flow

Aries Agent Authentication

authentication for aries agent making request to ledger.

• Aries agent sends SignedLedgerRequest to Ledger (chaincode)

export interface SignedLedgerRequest {
    reqId: number;
    identifier: string; // did of transaction caller
    operation:  {[key: string] : any};
    protocolVersion: number;
    signature: string; // signature of caller with it's private key corresponding to verkey of did caller.
}

• Chaincode authenticates caller by verifying signature, flow of signature verification should be:
  • get did from worldstate : getDID(request.identifier)
  • convert verkey to public key pub = ed25519.PublicKey(base58.Decode(did.verkey))
  • decode signature from base58 sign = base58.Decode(request.signature)
  • serialize message serialized_message = serialize(request)
  • verify signature valid = ed25519.Verify(pub, serialized_message, sign)

Chaincode initialization

Chaincode should be initialize with list of TRUSTEE :

[
   {
    "alias" : "",
    "dest" : "",
    "verkey" : "",
   } 
]

Registered TRUSTEE make nymTransaction

• Fabric Client Authentication
• Aries Agent Authentication
• Create new NYM if not existing

Create Schema

• Fabric Client Authentication
• Aries Agent Authentication, role >= ENDORSER
• Create new NYM if not existing
• ID = ${identifier}:2:${schema.name}:${schema.version}

Create Credential Definition

• Fabric Client Authentication
• Aries Agent Authentication, role >= ENDORSER
• Create new NYM if not existing
• ID = ${identifier}:3:${credDef.signature_type}:${hash64(schemaID)}:${credDef.tag}

Chaincode response

Success

{
    "op" : "READ" || "WRITE",
    "type" : "1" || "101" || "102", // transaction type
    "identifier" : "7jUk7gMNzBXgZvVGPdDVnx", // did of caller
    "data" : {
        // op and type specific data
    }
}

Error

{
    "op" : "READ" || "WRITE",
    "type" : "1" || "101" || "102", // transaction type
    "identifier" : "7jUk7gMNzBXgZvVGPdDVnx", // did of caller
    "reason" : "error message"  
}