TestDESede

//好神奇，密鑰每次都不一樣，但是就是能成功解密。
//Cipher 是爲加密和解密提供密碼功能。差不多就是。。。。給密鑰一個附加密碼。加解密操作的時候不僅需要拿到密鑰，還需要這個密碼
//所以上面說的密鑰不一樣，其實是每次的密碼都不一樣
import java.security.Key;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESedeKeySpec;

import org.apache.commons.codec.binary.Base64;

public class TestDESede {
	
	public static String KEY_ALGORITHM ="DESede";
	
	public static String CIPHER_ALOGITHM ="DESede/ECB/PKCS5Padding";
	
	public static void main(String[] args) throws Exception{
		String s = "DESede";
		System.out.println("原文： " + s);
		byte[] key = initKey();
		System.out.println("密鑰： " + Base64.encodeBase64String(key));
		byte[] afterEncrypt = encrypt(s.getBytes(), key);
		System.out.println("加密後:" + Base64.encodeBase64String(afterEncrypt));
		
		byte[] afterDecrypt = decrypt(afterEncrypt, key);
		System.out.println("解密後：" + new String(afterDecrypt));
		
	}
	
	public static byte[] initKey() throws Exception {
		KeyGenerator kg = KeyGenerator.getInstance(KEY_ALGORITHM);
		kg.init(168);
		SecretKey sk = kg.generateKey();
		return sk.getEncoded();
	}
	
	/**
	 * 轉換密鑰
	 * @param key
	 * @return
	 * @throws Exception
	 */
	public static Key toKey(byte[] key) throws Exception {
		//獲取密鑰模具，規範
		DESedeKeySpec dks = new DESedeKeySpec(key);
		//獲取密鑰工廠
		SecretKeyFactory skf = SecretKeyFactory.getInstance(KEY_ALGORITHM);
		//生成密鑰
		return skf.generateSecret(dks);
	}
	
	public static byte[] encrypt(byte[] date, byte[] key) throws Exception {
		//還原密鑰
		Key k = toKey(key);
		Cipher cipher = Cipher.getInstance(CIPHER_ALOGITHM);
		cipher.init(Cipher.ENCRYPT_MODE, k);
		return cipher.doFinal(date);
	}
	
	/**
	 * 解密
	 * @param date
	 * @param key
	 * @return
	 * @throws Exception
	 */
	public static byte[] decrypt(byte[] date, byte[] key) throws Exception {
		//還原密鑰
		Key k = toKey(key);
		Cipher cipher = Cipher.getInstance(CIPHER_ALOGITHM);
		cipher.init(Cipher.DECRYPT_MODE, k);
		return cipher.doFinal(date);
	}

}