genDpopToken function

Implementation

String genDpopToken(
  String endPointUrl,
  KeyPair rsaKeyPair,
  dynamic publicKeyJwk,
  String httpMethod,
) {
  /// https://datatracker.ietf.org/doc/html/draft-ietf-oauth-dpop-03
  /// Unique identifier for DPoP proof JWT
  /// Here we are using a version 4 UUID according to https://datatracker.ietf.org/doc/html/rfc4122
  var uuid = const Uuid();
  final String tokenId = uuid.v4();

  /// Initialising token head and body (payload)
  /// https://solid.github.io/solid-oidc/primer/#authorization-code-pkce-flow
  /// https://datatracker.ietf.org/doc/html/rfc7519
  var tokenHead = {'alg': 'RS256', 'typ': 'dpop+jwt', 'jwk': publicKeyJwk};

  var tokenBody = {
    'htu': endPointUrl,
    'htm': httpMethod,
    'jti': tokenId,
    'iat': (DateTime.now().millisecondsSinceEpoch / 1000).round(),
  };

  /// Create a json web token
  final jwt = JWT(
    tokenBody,
    header: tokenHead,
  );

  /// Sign the JWT using private key
  var dpopToken = jwt.sign(
    RSAPrivateKey(rsaKeyPair.privateKey),
    algorithm: JWTAlgorithm.RS256,
  );

  return dpopToken;
}