(Java) Verify JWT with EdDSA / Ed25519 Signature

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.

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import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    // 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

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

    CkPublicKey pubKey = new CkPublicKey();
    boolean success = pubKey.LoadFromString(jsonPubKey);
    if (success == false) {
        System.out.println(pubKey.lastErrorText());
        return;
        }

    CkJwt jwt = new CkJwt();
    String token = "eyJhbGciOiJFZERTQSJ9.RXhhbXBsZSBvZiBFZDI1NTE5IHNpZ25pbmc.hgyY0il_MGCjP0JzlnLWG1PPOt7-09PGcvMg3AIbQR6dWbhijcNR4ki4iylGjg5BhVsPt9g7sVvpAr_MuM0KAg";

    // First verify the signature.
    boolean sigVerified = jwt.VerifyJwtPk(token,pubKey);
    System.out.println("verified: " + sigVerified);

    if (sigVerified == false) {
        System.out.println(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.
    int leeway = 60;
    boolean bTimeValid = jwt.IsTimeValid(token,leeway);
    System.out.println("time constraints valid: " + bTimeValid);

    // Recover the original data (the payload).
    String payload = jwt.getPayload(token);
    System.out.println(payload);

    // Recover the original JOSE header in the same way:
    String joseHeader = jwt.getHeader(token);
    System.out.println(joseHeader);
  }
}