@mattrglobal/jsonld-signatures-bbs

jsonld-signatures-bbs

The following repository contains a linked data proof implementation for creating BBS+ Signatures using BLS12-381 key pairs.

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

Note At this time this project is limited to working in node environments because the underlying cryptographic implementation is supplied by node-bbs-signatures, however we are targeting support for other parts of the JS/TS ecosystem in the near future.

Getting started

To use this package within your project simply run

npm install @mattrglobal/jsonld-signatures-bbs

Or with Yarn

yarn add @mattrglobal/jsonld-signatures-bbs

Sample

See the sample directory for a runnable demo.

Examples

The following is an example of a signed JSON-LD document featuring a BBSSignature2020 type signature.

{
  "@context": [
    "https://www.w3.org/2018/credentials/v1",
    "https://w3id.org/citizenship/v1"
  ],
  "id": "https://issuer.oidp.uscis.gov/credentials/83627465",
  "type": ["VerifiableCredential", "PermanentResidentCard"],
  "issuer": "did:example:489398593",
  "identifier": "83627465",
  "name": "Permanent Resident Card",
  "description": "Government of Example Permanent Resident Card.",
  "issuanceDate": "2019-12-03T12:19:52Z",
  "expirationDate": "2029-12-03T12:19:52Z",
  "credentialSubject": {
    "id": "did:example:b34ca6cd37bbf23",
    "type": ["PermanentResident", "Person"],
    "givenName": "JOHN",
    "familyName": "SMITH",
    "gender": "Male",
    "image": "data:image/png;base64,iVBORw0KGgokJggg==",
    "residentSince": "2015-01-01",
    "lprCategory": "C09",
    "lprNumber": "999-999-999",
    "commuterClassification": "C1",
    "birthCountry": "Bahamas",
    "birthDate": "1958-07-17"
  },
  "proof": {
    "type": "BbsBlsSignature2020",
    "created": "2020-04-26T04:21:07Z",
    "verificationMethod": "did:example:489398593#test",
    "proofPurpose": "assertionMethod",
    "signature": "jx2VhjyZqUT91e2OhzweJA7G2u2UvmiDtIfmr+wUWNHWno+UOAh0FaNpM8Br+5j2JBkH981/nO1I7/9PFaRrng6NXu7vzDroKtuyj6nHGkMmGq4OMmBzIqRnG3ybin/Sxmu5YwqOxPMRsWH3H+2wSA=="
  }
}

Whereby a zero knowledge proof disclosing only givenName, familyName and gender can be derived, from the above assertion using the following as the reveal document which is a JSON-LD frame.

{
  "@context": [
    "https://www.w3.org/2018/credentials/v1",
    "https://w3id.org/citizenship/v1"
  ],
  "type": ["VerifiableCredential", "PermanentResidentCard"],
  "credentialSubject": {
    "type": ["PermanentResident", "Person"],
    "@explicit": true,
    "givenName": {},
    "familyName": {},
    "gender": {}
  }
}

That gives rise to the output zero knowledge proof

{
  "@context": [
    "https://www.w3.org/2018/credentials/v1",
    "https://w3id.org/citizenship/v1"
  ],
  "id": "https://issuer.oidp.uscis.gov/credentials/83627465",
  "type": ["PermanentResidentCard", "VerifiableCredential"],
  "description": "Government of Example Permanent Resident Card.",
  "identifier": "83627465",
  "name": "Permanent Resident Card",
  "credentialSubject": {
    "id": "did:example:b34ca6cd37bbf23",
    "type": ["Person", "PermanentResident"],
    "familyName": "SMITH",
    "gender": "Male",
    "givenName": "JOHN"
  },
  "expirationDate": "2029-12-03T12:19:52Z",
  "issuanceDate": "2019-12-03T12:19:52Z",
  "issuer": "did:example:489398593",
  "proof": {
    "type": "BbsBlsSignatureProof2020",
    "created": "2020-05-25T23:07:10Z",
    "verificationMethod": "did:example:489398593#test",
    "proofPurpose": "assertionMethod",
    "proofValue": "ABgA/4N3qygQRJlX3gmQOlJRGbO1KTXKQUmaN02xl+FiNZUDmGfa5OoKtg0RJ4wxxA08t3Vut61G/pq4yN0bygaFk5EJF6j7zFXmz9Vc7EdlDAvUkXqPaKA8inSBNv97HiZ1o5hIpoRnepW89p4JXPVrFi8XbDARSZpCg18GUuUMaPQLHKU82M/9l8tqqG1lKBOs+sRAAAAAdKRrRPj6zAz5LPZgDZJ0J2rNJjQI+JNYbV4AYEVwW37sxQ99aGGvmBk3DL0sod1V/gAAAAJMLYjmrb92zV087wO8UtFLwMj7qJuqV9VkMDghdrrc3BGtJuQgKx2GTrOb4CQxI1bf+iG0USjTktcjTlKv3X5spg3+ihOnyve0HnMWWggAW22j8b78jbl7lkYGJvzIXTzrVJ5KdYp3tXMDTAX7CLEXAAAACVY8oocA9Bz1w42F8Yv7UAPHv4pSvunXqndFOet3kWtzYHYEbO5gc42wPQtLmTtmqP6kUbQv6ruxzRmANulB8fUfy2jah/QeHKvsp907YDnSfo2wofRxa/vzsZnVriw0UmZnP0sYjbhmCkhoQZkxhqel3IkOF+H80wzvCKCl6eq5biEFMYA4bXpDX6Ap5/6WS5SSFaJRWxW+hpR/9EuQE11sGtk2W2Wn4eBrQUgVqYgPLI+U/ONaUJrh+GVJ/XXx7xxbAUf/NeQ/13AkTnYNn1fUdiOJ2oKl1lGr59udFq2tBBsyC3msTtQPYJS084355GRBur5jnzPNJ2W6Gu3ZqqQeRrVyw1gzdhVDNOE8KUm9OQ3AvCuxo8PHNrqzNvc6VA==",
    "nonce": "37pdwue1a8FWLqgwCd0QJ0IJTFhp609KtxeCTWZGnfAVE+sOBDffYez+TY/bmVy+6z4="
  }
}

Getting started as a contributor

The following describes how to get started as a contributor to this project

Prerequisites

The following is a list of dependencies you must install to build and contribute to this project

• Yarn
• Rust

For more details see our contribution guidelines

Install

To install the package dependencies run:

yarn install --frozen-lockfile

Build

To build the project run:

yarn build

Test

To run the test in the project run:

yarn test

Relevant 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