(学习笔记)Java的3DES与DES加密实现

package DESede;

import java.security.Key;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class DESede
{
private final static String encryptType = "DESede";//DESede或者DES

public static void main(String[] args) throws Exception
{
//生成随机密钥,如果不想系统自动生成，则自定义密钥，根据需求而定
//		KeyGenerator keygen = KeyGenerator.getInstance(encryptType);
//		SecureRandom random = new SecureRandom();
//		keygen.init(random);
//		byte [] key = keygen.generateKey().getEncoded();
//自定义DESede的密钥，必须为24字节
byte [] key = "abcdefghijklmnopqrstuvwx".getBytes();
//如果是DES加密，密钥必须为8字节即可
//byte [] key = "abcdefgh".getBytes();
//需要加密的内容
byte [] content = "admin".getBytes();
System.out.println("加密前的内容为:"+new String(content));
//加密内容并转化为16进制的字符串
String encryptContent =byteTo16(encrypt(key, content));
//打印密文
System.out.println("加密后的内容为:"+encryptContent);
//将加密的16进制字符串转换为byte字节数组
byte [] encryptContentByte = toByteArray(encryptContent);
//解密,并打印出原文
System.out.println("解密后的内容为:"+new String(decrypt(key,encryptContentByte)));
}

/**
* 将byte字节数组转换为16进制的字符串
* b 需要转换的字节数组
* **/
public static String byteTo16(byte [] b)
{
StringBuffer result = new StringBuffer();
for(int i = 0;i<b.length;i++)
{
if((b[i]&0xff)<0x10)
{
result.append("0");
}
result.append(Long.toString(b[i]&0xff, 16));
}
return result.toString().toUpperCase();
}

/**
* 将16进制的字符串转换为byte字节数组
* **/
public static byte [] toByteArray(String str16)
{
char [] c = str16.toCharArray();
byte [] b = new byte[c.length/2];
for(int i = 0;i<b.length;i++)
{
int pos = i * 2;
b[i] = (byte)("0123456789ABCDEF".indexOf(c[pos]) << 4 | "0123456789ABCDEF".indexOf(c[pos+1]));
}
return b;
}

/**
* DESede加密
* k 密钥
* content 加密内容
* */
public static byte [] encrypt(byte [] k,byte [] content)
{
try
{
SecretKey key = new SecretKeySpec(k, encryptType);
Cipher cipher = Cipher.getInstance(encryptType);
cipher.init(Cipher.ENCRYPT_MODE, key);
return cipher.doFinal(content);
}
catch (Exception e)
{
e.printStackTrace();
}
return null;
}

/**
* DESede解密
* k 密钥
* content 解密内容
* */
public static byte [] decrypt(byte [] k,byte [] content)
{
try
{
SecretKey key = new SecretKeySpec(k, encryptType);
Cipher cipher = Cipher.getInstance(encryptType);
cipher.init(Cipher.DECRYPT_MODE, key);
return cipher.doFinal(content);
}
catch(Exception e)
{
e.printStackTrace();
}
return null;
}
}