(Android™) 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.

Chilkat Android™ Downloads Android™ Java Libraries Android C/C++ Libraries

// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // 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) {
        Log.i(TAG, 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);
    Log.i(TAG, "verified: " + String.valueOf(sigVerified));

    if (sigVerified == false) {
        Log.i(TAG, 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);
    Log.i(TAG, "time constraints valid: " + String.valueOf(bTimeValid));

    // Recover the original data (the payload).
    String payload = jwt.getPayload(token);
    Log.i(TAG, payload);

    // Recover the original JOSE header in the same way:
    String joseHeader = jwt.getHeader(token);
    Log.i(TAG, joseHeader);

  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}