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github.com/nuts-foundation/go-did

A library to parse and generate W3C DID Documents and W3C Verifiable Credentials.

Example usage

Note on parsing: in earlier versions, DID documents, credentials and presentations were parsed using UnmarshalJSON. Now, ParseDocument(), ParseVerifiableCredential() and ParseVerifiablePresentation() should be used instead: they better support VCs and VPs in JWT format.

Parsing a DID document

didDoc, err := did.ParseDocument(didDocJson)
if err != nil {
    panic(err)
}
// do something with didDoc

Creating a DID document

Creation of a simple DID Document which is its own controller and contains an AssertionMethod.

didID, err := did.ParseDID("did:example:123")

// Empty did document:
doc := &did.Document{
    Context:            []did.URI{did.DIDContextV1URI()},
    ID:                 *didID,
}

// Add an assertionMethod
keyID, _ =: did.ParseDIDURL("did:example:123#key-1")

keyPair, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
verificationMethod, err := did.NewVerificationMethod(*keyID, did.JsonWebKey2020, did.DID{}, keyPair.Public())

// This adds the method to the VerificationMethod list and stores a reference to the assertion list
doc.AddAssertionMethod(verificationMethod)

didJson, _ := json.MarshalIndent(doc, "", "  ")
fmt.Println(string(didJson))

Outputs:

{
  "assertionMethod": [
    "did:example:123#key-1"
  ],
  "@context": "https://www.w3.org/ns/did/v1",
  "controller": "did:example:123",
  "id": "did:example:123",
  "verificationMethod": [
    {
      "controller": "did:example:123",
      "id": "did:example:123#key-1",
      "publicKeyJwk": {
        "crv": "P-256",
        "kty": "EC",
        "x": "UANQ8pgvJT33JbrnwMiu1L1JCGQFOEm1ThaNAJcFrWA=",
        "y": "UWm6q5n1iXyeCJLMGDInN40bkkKr8KkoTWDqJBZQXRo="
      },
      "type": "JsonWebKey2020"
    }
  ]
}

Parsing Verifiable Credentials and Verifiable Presentations

The library supports parsing of Verifiable Credentials and Verifiable Presentations in JSON-LD, and JWT proof format. Use ParseVerifiableCredential(raw string) and ParseVerifiablePresentation(raw string).

Supported key types

• JsonWebKey2020
• Ed25519VerificationKey2018
• EcdsaSecp256k1VerificationKey2019 (pass build tag to enable: -tags=jwx_es256k)

Installation

go get github.com/nuts-foundation/go-did

Testing

go test ./... -tags=jwx_es256k

State of the library

We keep the API stable, breaking changes will only be introduced in new major versions.