Signing Agreements

The LigoAgreement and LigoAgreementState objects are stored in IPFS using the DAG-JOSE codec. They are signed by both parties and encrypted.

This document describes how the agreements are signed. The result should be used in Encryption and Decryption as the payload. That means agreements and state are signed and then encrypted.

See a working example here.

Signing

This is an example of signing an agreement, taken from the js-dag-jose example.

import { DID } from 'dids'

const agreement: LigoAgreement = ...
const didA: DID = ...
const didB: DID = ...

// 1. Create initial JWS with didA
const jwsA = await did.createJWS(agreement)

// 2. Send JWS to other party...

// 3. Other party signs with didB
const jwsB = await didB.createJWS(jwsB.payload);

// 4. Form final JWS signed by both parties
const jws = { ...jwsA, signatures: [...jwsA.signatures, ...jwsB.signatures] };

See Encryption and Decryption for how to encrypt this object and put it in IPFS.

Verifying

Both parties' signatures need to be verified independently.

import { DID } from 'dids'

const didA: DID = ...
const didB: DID = ...


const retrievedJWSA = {
    ...jws,
    // Filter signatures for didA key
    signatures: jws.signatures.filter(
      (v) =>
        JSON.parse(u8a.toString(base64ToBytes(v.protected)))["kid"].split(
          "#"
        )[0] === didA.id
    ),
};
const verifiedJWSA = await didA.verifyJWS(retrievedJWSA);


const retrievedJWSB = {
    ...jws,
    // Filter signatures for didB key
    signatures: jws.signatures.filter(
      (v) =>
        JSON.parse(u8a.toString(base64ToBytes(v.protected)))["kid"].split(
          "#"
        )[0] === didB.id
    ),
};
const verifiedJWSB = await didB.verifyJWS(retrievedJWSB);