DID and Verifiable Credential SDK

This SDK enables the management of Decentralized Identifiers (DIDs) and Verifiable Credentials (VCs). It supports creating, verifying.

Supported signatures:

• BBS+

Installation

To install the SDK, use yarn:

yarn install

Functions

The SDK exposes following functions:

• bbsDidFromPublicKey: Creates a DID from a BBS+ public key.
• blsG2PublicKeyFromPrivateKey: Retrieves the BBS+ public key from a BBS+ private key.
• createBbsCredential: Creates a BBS+ credential with the specified parameters.
• makeBBSPlusProof: Creates a BBS+ proof for a set of messages using the provided private key and public key. The function signs the messages using the BLS signature algorithm and constructs a proof object with the necessary metadata, including the type, proof purpose, verification method, creation date, and mandatory pointers.
• makeBBSPlusW3cProof: Creates a BBS+ proof for a set of messages using the provided private key and public key. It exactly follows the W3C specification for VCs with BBS+ signatures. Which means RDF Canonicalization is used to create the messages, the mandatory messages and the proof config are hashed and included in the header of the BBS+ signature. The proof value contains additional cbor encoded metadata, like mandatory pointers...
• blsSignMessages: Signs the provided messages using the BBS signature algorithm and returns the signature. There is currently a difference with the IETF BBS signature standard: the header message is included as message 0 in the signature.
• getMessages: Extracts and processes messages from the given data based on specified mandatory fields. This is used for preparing messages for BBS+ signatures.
• getGroupedMessages: Traverses a data object, extracting data as messages and grouping them into mandatory and non-mandatory categories based on specified paths. This function also ensures that all specified mandatory fields are covered in the data provided.

Usage

Below is an example on how to issue, verify, and optionally revoke a verifiable credential using the BBS+ signature scheme.

Example: Issue and Verify a Verifiable Credential

import { BbsDID, createBbsCredential, verifyBbsVc } from '@terminal3/bbc_vc';

// Issuer's private key and setup
const issuerPrivateKey = 'private_key_here';
const issuer = new BbsDID(privateKey);

// Holder's DID
const holderDid = 'did:example:b34ca6cd37bbf23';

// Creating a credential with BBS+ signature
const claims = { kyc: 'passed' };
const revocationRegistryAddress = '0x77Fb69B24e4C659CE03fB129c19Ad591374C349e';
const didRegistryAddress = '0x312C15922c22B60f5557bAa1A85F2CdA4891C39a';
const provider = new ethers.JsonRpcProvider(process.env.TEST_BLOCKCHAIN_URL);
const options = {
  revocationRegistryAddress,
  provider,
  didRegistryAddress,
} as VerificationOptions;
const credential = await createBbsCredential(
  bbsIssuer,
  userDid,
  cred_subject,
  ['KycCredential'], // type
  undefined, // valid from
  undefined, // valid until
  options,
);
console.log('Credential Issued:', credential);

// Verifying the credential
const verificationResult = await verifyBbsVC(credential);
console.log('Verification Result:', verificationResult);