Android™

Duplicate .NET's Rfc2898DeriveBytes Functionality

See more Encryption Examples

Demonstrates how to duplicate the results produced by .NET's System.Security.Cryptography.Rfc2898DeriveBytes class. 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);

    // This example assumes Chilkat Crypt2 to have been previously unlocked.
    // See Unlock Crypt2 for sample code.

    // This example demonstrates how to duplicate the results produced
    // by .NET's System.Security.Cryptography.Rfc2898DeriveBytes class.

    // For example, here is C# code that transforms a password string into
    // bytes that can be used as a secret key for symmetric encryption (such as AES, blowfish, 3DES, etc.)
    // 
    //     Rfc2898DeriveBytes deriveBytes = new Rfc2898DeriveBytes("secret", System.Text.Encoding.UTF8.GetBytes("saltsalt123"), numIterations);
    //     byte[] secretKeyBytes = deriveBytes.GetBytes(numBytes);

    // (The Rfc2898DeriveBytes computation is really just the PBKDF2 algorithm with SHA-1 hashing.)
    // In Chilkat, this is what we do to match...

    // First, let's get a test vector with known results.  Both Chilkat AND Microsoft should produce
    // the same results.  RFC 6070 has some PBKDF2 HMAC-SHA1 Test Vectors.  Here is one of them:

    //      Input:
    //        P = "passwordPASSWORDpassword" (24 octets)
    //        S = "saltSALTsaltSALTsaltSALTsaltSALTsalt" (36 octets)
    //        c = 4096
    //        dkLen = 25
    // 
    //      Output:
    //        DK = 3d 2e ec 4f e4 1c 84 9b
    //             80 c8 d8 36 62 c0 e4 4a
    //             8b 29 1a 96 4c f2 f0 70
    //             38                      (25 octets)
    // 
    // 

    CkCrypt2 crypt = new CkCrypt2();

    String salt = "saltSALTsaltSALTsaltSALTsaltSALTsalt";
    // Given that the salt is really binary data (can be any random bunch of bytes),
    // we must pass the exact hex string representation of the salt bytes.
    // In this case, we're getting the utf-8 byte representation of our salt string,
    // which is identical to the us-ascii byte representation because there are no 8bit chars..
    String saltHex = crypt.encodeString(salt,"utf-8","hex");

    // Duplicate the test vector as shown above.
    String dkHex = crypt.pbkdf2("passwordPASSWORDpassword","utf-8","sha1",saltHex,4096,25 * 8,"hex");
    Log.i(TAG, dkHex);

  }

  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."
  }
}