Android™

Ed25519 Key Exchange (Shared Secret)

See more Ed25519 Examples

Demonstrates how to create an Ed25519 shared secret for use in key exchange.

Note: This example requires Chilkat v9.5.0.83 or greater.

Android™

// 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);

    boolean success = false;

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

    // Alice's private key, a:
    //     77076d0a7318a57d3c16c17251b26645df4c2f87ebc0992ab177fba51db92c2a
    // Alice's public key, X25519(a, 9):
    //     8520f0098930a754748b7ddcb43ef75a0dbf3a0d26381af4eba4a98eaa9b4e6a
    // Bob's private key, b:
    //     5dab087e624a8a4b79e17f8b83800ee66f3bb1292618b6fd1c2f8b27ff88e0eb
    // Bob's public key, X25519(b, 9):
    //     de9edb7d7b7dc1b4d35b61c2ece435373f8343c85b78674dadfc7e146f882b4f
    // Their shared secret, K:
    //     4a5d9d5ba4ce2de1728e3bf480350f25e07e21c947d19e3376f09b3c1e161742

    String alicePrivKey = "77076d0a7318a57d3c16c17251b26645df4c2f87ebc0992ab177fba51db92c2a";
    String bobPubKey = "de9edb7d7b7dc1b4d35b61c2ece435373f8343c85b78674dadfc7e146f882b4f";

    CkPrivateKey privKey = new CkPrivateKey();
    // This example shows only one way of loading an Ed25519 private key.
    // Chilkat can load other formats (JWK, PEM, ASN.1 DER, etc.)  
    // You may do so by calling LoadAnyFormat or LoadAnyFormatFile.
    success = privKey.LoadEd25519(alicePrivKey,"");
    if (success == false) {
        Log.i(TAG, privKey.lastErrorText());
        return;
        }

    CkPublicKey pubKey = new CkPublicKey();
    success = pubKey.LoadEd25519(bobPubKey);
    if (success == false) {
        Log.i(TAG, pubKey.lastErrorText());
        return;
        }

    // Create the shared secret:
    CkEdDSA eddsa = new CkEdDSA();
    String sharedSecret = eddsa.sharedSecretENC(privKey,pubKey,"hexlower");
    if (eddsa.get_LastMethodSuccess() == false) {
        Log.i(TAG, eddsa.lastErrorText());
        return;
        }

    Log.i(TAG, "Computed: " + sharedSecret);
    Log.i(TAG, "Expected: 4a5d9d5ba4ce2de1728e3bf480350f25e07e21c947d19e3376f09b3c1e161742");

  }

  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."
  }
}