(Android™) AES 256-bit CBC using PBKDF2 Generated Secret Key

See more Encryption Examples

First generates a 32-byte secret key using PBKDF2 (with HMAC-SHA256), and then uses the secret key to do 256-bit AES CBC mode decryption.

(Duplicates the following Java code)

public String decrypt(String strToDecrypt) {
        try  {
            // Read the initialization vector from the first bytes for the data
            byte [] rawData = Base64.getDecoder().decode(strToDecrypt);
            byte [] iv = new byte[Config.get().encryptionIVLength()];
            byte [] encryptedData = new byte[rawData.length - iv.length];
            System.arraycopy(rawData, 0, iv, 0, iv.length);
            System.arraycopy(rawData, iv.length, encryptedData, 0, encryptedData.length);
 
            IvParameterSpec ivspec = new IvParameterSpec(iv);
 
            SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
            KeySpec spec = new PBEKeySpec(secretKey.toCharArray(), salt.getBytes(), 65536, 256);
            SecretKey tmp = factory.generateSecret(spec);
            SecretKeySpec secretKey = new SecretKeySpec(tmp.getEncoded(), "AES");
 
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
            cipher.init(Cipher.DECRYPT_MODE, secretKey, ivspec);
            return new String(cipher.doFinal(encryptedData));
        }
        catch (Exception e) {
            log.error("Could not decrypt the string.", e);
        }
        return null;
    }

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);

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

    CkCrypt2 crypt = new CkCrypt2();

    String password = "some arbitrary length password";
    // We have 8 bytes of salt encoded using hex.
    // (The salt can be any number of bytes, in any desired encoding such as base64, hex, etc.)
    String saltHex = "0102030405060708";

    // Generate the 256-bit (32-byte) AES secret key we'll use to decrypt.
    int iterationCount = 65536;
    int outputKeyBitLen = 256;
    String secretKeyHex = crypt.pbkdf2(password,"utf-8","sha256",saltHex,iterationCount,outputKeyBitLen,"hex");

    // Setup for 256-bit AES CBC decryption.
    crypt.put_CryptAlgorithm("aes");
    crypt.put_KeyLength(256);
    crypt.put_CipherMode("cbc");
    crypt.put_PaddingScheme(0);

    // The IV for AES is 16 bytes.
    String iv = "000102030405060708090A0B0C0D0E0F";
    crypt.SetEncodedIV(iv,"hex");

    // Set the secret key for 256-bit AES.
    crypt.SetEncodedKey(secretKeyHex,"hex");

    // AES decrypt
    // assume our string to decrypt is base64
    String strToDecrypt = "....";
    crypt.put_EncodingMode("base64");
    String decryptedStr = crypt.decryptStringENC(strToDecrypt);

    Log.i(TAG, decryptedStr);

  }

  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."
  }
}