(Android™) HMAC Hex String

Demonstrates how to compute an HMAC using a hexidecimal key and 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);

    CkCrypt2 crypt = new CkCrypt2();

    boolean success = crypt.UnlockComponent("Anything for 30-day trial");
    if (success != true) {
        Log.i(TAG, crypt.lastErrorText());
        return;
        }

    //  Set the MAC algorithm to HMAC
    crypt.put_MacAlgorithm("hmac");

    //  Our HMAC key will be the bytes represented in the following hex string.
    //  In other words, the HMAC key is composed of the bytes 0x41, 0xC2, 0x1C, ...
    //  (It is not composed of the us-ascii string '4', '1', 'C', ...)
    String keyHex = "41C21CB9D7A02FC5D4FADB9E4755B9DE";
    success = crypt.SetMacKeyEncoded(keyHex,"hex");

    //  Our desire is to HMAC the bytes represented in the following string:
    String dataHex = "C22078065B01460001000000010062043BF5B18228C8E02D17BCFE4E00561FA6DEC216EA97195CEB579942E275C21932258E3CD391E507FF4E7FD4C787A8447DA111C54A9C1795E7FF4C0BAA2EDA";

    //  We'll need to decode the hex to binary:
    CkBinData bd = new CkBinData();
    bd.AppendEncoded(dataHex,"hex");

    //  Do the HMAC-SHA256 hash and return as a hex string:
    crypt.put_EncodingMode("hex");
    crypt.put_HashAlgorithm("sha-256");
    String macHex = crypt.macBdENC(bd);
    Log.i(TAG, macHex);

  }

  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."
  }
}