@mattrglobal/jsonld-signatures-bbs

jsonld-signatures-bbs

The following repository contains the specification and a reference implementation for generating linked data signatures using the BBS+ Signature Algorithm using BLS12-381 key pairs.

Due to the properties of a BBS+ Signatures a zero knowledge proof can be derived from the signature, whereby the party generating the proof can elect to selectively disclose statements from the originally signed payload.

Getting Started

To install

yarn install --frozen-lockfile

To run the tests

yarn test

Sample Credential

The following is an example of a signed JSON-LD document featuring a BBS+ linked data signature.

{
  "@context": [
    "https://www.w3.org/2018/credentials/v1",
    "https://w3id.org/citizenship/v1"
  ],
  "type": ["VerifiableCredential", "PermanentResidentCard"],
  "issuer": "did:example:28394728934792387",
  "issuanceDate": "2019-12-03T12:19:52Z",
  "expirationDate": "2029-12-03T12:19:52Z",
  "credentialSubject": {
    "type": ["PermanentResident", "Person"],
    "givenName": "JOHN",
    "familyName": "SMITH",
    "gender": "Male",
    "image": "data:image/png;base64,iVBORw0KGgo...kJggg==",
    "residentSince": "2015-01-01",
    "lprCategory": "C09",
    "lprNumber": "999-999-999",
    "commuterClassification": "C1",
    "birthCountry": "Bahamas",
    "birthDate": "1958-07-17"
  },
  "proof": {
     "type": "BBSSignature2020",
     "signature": "eyJhbGciOiJFZERTQSIsI...wRG2fNmAx60Vi4Ag",
     "requiredRevealStatements": [ 1, 2, 3, 4, 10],
     "proofPurpose": "assertionMethod",
     "verificationMethod": "did:example:28394728934792387#keys-7f83he7s8",
     "subjectVerificationMethod": "did:example13920596349402396#keys-5920692"
  }
}

Whereby the subject is able to generate a zero knowledge proof, from the signed JSON-LD document of the form.

{
  "@context": [
    "https://www.w3.org/2018/credentials/v1",
    "https://w3id.org/citizenship/v1"
  ],
  "type": ["VerifiableCredential", "PermanentResidentCard"],
  "issuer": "did:example:28394728934792387",
  "issuanceDate": "2019-12-03T12:19:52Z",
  "expirationDate": "2029-12-03T12:19:52Z",
  "credentialSubject": {
    "type": ["PermanentResident", "Person"],
    "givenName": "JOHN",
    "familyName": "SMITH",
    "commuterClassification": "C1",
    "birthCountry": "Bahamas",
    "birthDate": "1958-07-17"
  },
  "proof": {
     "type": "BBSSignatureProof2020",
     "proof": "eyJhbGciOiJFZERTQSIsI...wRG2fNmAx60Vi4Ag",
     "domain": "did:example:relying-party",
     "subjectDomainProof": "eigqeivIenvIEiHtiW...6ChjkeIchjs"
     "requiredRevealStatements": [ 1, 2, 3, 4, 10],
     "revealedAttributes": [ 1, 2, 3, 4, 5 ],
     "totalAttributes": 10,
     "proofPurpose": "assertionMethod",
     "verificationMethod": "did:example:28394728934792387#keys-7f83he7s8"
  }
}

References

• BLS12-381 For The Rest Of Us
• Pairing-based cryptography
• Exploring Elliptic Curve Pairings
• BBS+ Signature Scheme
• Anonymous Attestation Using the Strong Diffie Hellman Assumption Revisited
• Pairing Friendly Curves Draft RFC