Dart

Verify JWT with EdDSA / Ed25519 Signature

See more JSON Web Token (JWT) Examples

Note: This example requires Chilkat v9.5.0.84 or greater.

Demonstrates how to verify a JWT that was signed using an Ed25519 private key.

This example verifies the EdDSA signature. It also does the following:

• Checks to see if the time constraints ("nbf" and "exp") are valid.
• Recovers the original JOSE header.
• Recovers the original data.

Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // Demonstrates how to verify a JWT with an EdDSA/Ed25519 Signature
  // *** Requires Chilkat v9.5.0.84 or greater.

  // This example assumes the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  // Use this Ed25519 public key for verification

  final jsonPubKey = '{"kty": "OKP","alg": "EdDSA","crv": "Ed25519","x": "11qYAYKxCrfVS_7TyWQHOg7hcvPapiMlrwIaaPcHURo"}';

  final pubKey = CkPublicKey();
  try {
    pubKey.loadFromString(jsonPubKey);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final jwt = CkJwt();
  final token = 'eyJhbGciOiJFZERTQSJ9.RXhhbXBsZSBvZiBFZDI1NTE5IHNpZ25pbmc.hgyY0il_MGCjP0JzlnLWG1PPOt7-09PGcvMg3AIbQR6dWbhijcNR4ki4iylGjg5BhVsPt9g7sVvpAr_MuM0KAg';

  // First verify the signature.
  var sigVerified = true;
  try {
    jwt.verifyJwtPk(token, pubKey);
  } on ChilkatException {
    sigVerified = false;
  }
  print('verified: $sigVerified');

  if (!sigVerified) {
    print(jwt.lastErrorText);
    return;
  }

  // Let's see if the time constraints, if any, are valid.
  // The above JWT was created on the afternoon of 16-May-2016, with an expiration of 1 hour.
  // If the current system time is before the "nbf" time, or after the "exp" time,
  // then IsTimeValid will return false/0.
  // Also, we'll allow a leeway of 60 seconds to account for any clock skew.
  // Note: If the token has no "nbf" or "exp" claim fields, then IsTimeValid is always true.
  final leeway = 60;
  final bTimeValid = jwt.isTimeValid(token, leeway);
  print('time constraints valid: $bTimeValid');

  // Recover the original data (the payload).
  final payload = jwt.getPayload(token);
  print(payload);

  // Recover the original JOSE header in the same way:
  final joseHeader = jwt.getHeader(token);
  print(joseHeader);
}