DESDecrypt.java

package org.beanfuse.security.codec;

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;


public class DESDecrypt
{

    public DESDecrypt(byte desKey[])
    {
        this.desKey = desKey;
    }

    public byte[] doDecrypt(byte encryptText[])
        throws Exception
    {
        SecureRandom sr = new SecureRandom();
        byte rawKeyData[] = desKey;
        DESKeySpec dks = new DESKeySpec(rawKeyData);
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
        javax.crypto.SecretKey key = keyFactory.generateSecret(dks);
        Cipher cipher = Cipher.getInstance("DES");
        cipher.init(2, key, sr);
        byte encryptedData[] = encryptText;
        byte decryptedData[] = cipher.doFinal(encryptedData);
        return decryptedData;
    }

    public static void main(String args[])
        throws Exception
    {
        String key = "ABCDEFGH";
        String value = "AABBCCDDEE";
        DESEncrypt desEncrypt = new DESEncrypt(key.getBytes());
        byte encryptText[] = desEncrypt.doEncrypt(value.getBytes());
        System.out.println("doEncrypt - " + toHexString(encryptText));
        System.out.println("doEncrypt - " + new String(encryptText));
        DESDecrypt desDecrypt = new DESDecrypt(key.getBytes());
        byte decryptText[] = desDecrypt.doDecrypt(encryptText);
        System.out.println("doDecrypt - " + new String(decryptText));
        System.out.println("doDecrypt - " + toHexString(decryptText));
    }

    public static String toHexString(byte value[])
    {
        String newString = "";
        for(int i = 0; i < value.length; i++)
        {
            byte b = value[i];
            String str = Integer.toHexString(b);
            if(str.length() > 2)
                str = str.substring(str.length() - 2);
            if(str.length() < 2)
                str = "0" + str;
            newString = newString + str;
        }

        return newString.toUpperCase();
    }

    private byte desKey[];
}