Android DES Decrypt decrypt(String data, String key)

Description

decrypt

Declaration

public static String decrypt(String data, String key) throws Exception 

Method Source Code

//package com.java2s;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import android.util.Base64;

public class Main {
    private static final String CIPHER_ALGORITHM = "AES";
    private static final String RANDOM_GENERATOR_TYPE = "SHA1PRNG";
    private static final int RANDOM_KEY_SIZE = 128;

    public static String decrypt(String data, String key) throws Exception {
        byte[] myKey = generateKey(key.getBytes());

        // Grab secret key
        SecretKeySpec spec = new SecretKeySpec(myKey, CIPHER_ALGORITHM);
        Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, spec);

        // Decrypt data
        byte[] encryptedData = Base64.decode(data, Base64.DEFAULT);
        byte[] decryptedData = cipher.doFinal(encryptedData);

        // Convert to string
        String result = new String(decryptedData);

        return result;
    }//  w ww  . j  ava2  s . co m

    public static byte[] generateKey(byte[] randomSeed) throws Exception {
        // Set up generators
        KeyGenerator gen = KeyGenerator.getInstance(CIPHER_ALGORITHM);
        SecureRandom rand = SecureRandom.getInstance(RANDOM_GENERATOR_TYPE);
        rand.setSeed(randomSeed);

        // Generate key
        gen.init(RANDOM_KEY_SIZE, rand);
        SecretKey myKey = gen.generateKey();

        return myKey.getEncoded();
    }
}

Related

1. decode(String key, String data)
2. desDecodeCBC(byte[] key, byte[] keyiv, byte[] data)
3. desDecodeECB(byte[] key, byte[] data)
4. decryptDES(String decryptString, String decryptKey)