本篇主要是实现标题中的三个加密算法，至于机制大家自行百度吧。
一、DES
实现类：DES.java
package com.kale.des;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
/*
* DES加密介绍
DES是一种对称加密算法，所谓对称加密算法即：加密和解密使用相同密钥的算法。
DES加密算法出自IBM的研究，后来被美国政府正式采用，之后开始广泛流传，但是近些年使用越来越少，
因为DES使用56位密钥，以现代计算能力，24小时内即可被破解。虽然如此，在某些简单应用中，我们还是可
以 使用DES加密算法，本文简单讲解DES的JAVA实现。
*/
public class DES{
/**
* 加密过程，密钥长度都必须是8的倍数
* @param datasource
* @param password
* @return 加密后的结果
*/
public static byte[] desLock(byte[] datasource, String password) {
try{
SecureRandom random = new SecureRandom();
DESKeySpec desKey = new DESKeySpec(password.getBytes());
//创建一个密匙工厂，然后用它把DESKeySpec转换成
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
SecretKey securekey = keyFactory.generateSecret(desKey);
//Cipher对象实际完成加密操作
Cipher cipher = Cipher.getInstance("DES");
//用密匙初始化Cipher对象
cipher.init(Cipher.ENCRYPT_MODE, securekey, random);
//现在，获取数据并加密
//正式执行加密操作
return cipher.doFinal(datasource);
}catch(Throwable e){
e.printStackTrace();
}
return null;
}
/**
* 解密过程，密钥长度都必须是8的倍数
* @param src
* @param password
* @return 解密后的内容
* @throws Exception
*/
public static byte[] desUnclock(byte[] src, String password) throws Exception {
// DES算法要求有一个可信任的随机数源
SecureRandom random = new SecureRandom();
// 创建一个DESKeySpec对象
DESKeySpec desKey = new DESKeySpec(password.getBytes());
// 创建一个密匙工厂
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
// 将DESKeySpec对象转换成SecretKey对象
SecretKey securekey = keyFactory.generateSecret(desKey);
// Cipher对象实际完成解密操作
Cipher cipher = Cipher.getInstance("DES");
// 用密匙初始化Cipher对象
cipher.init(Cipher.DECRYPT_MODE, securekey, random);
// 真正开始解密操作
return cipher.doFinal(src);
}
}
测试类：DesTest.java
package com.kale.des;
public class DesTest {
/**
* @param args
*/
public static void main(String[] args) {
// TODO 自动生成的方法存根
//待加密内容
String str = "kale123456789";
//密码，长度要是8的倍数
String password = "12345678";
byte[] result = null;
try{
result = DES.desLock(str.getBytes(),password);
System.out.println("加密后内容为："+new String(result));
}
catch(Exception e){
System.out.println("加密失败！");
}
//解密
try {
byte[] unLockResult = DES.desUnclock(result, password);
System.out.println("解密后内容为："+new String(unLockResult));
}
catch (Exception e1) {
//e1.printStackTrace();
System.out.println("密钥错误，无法解密！");
}
}
}
结果：
加密后内容为：S??:?[email protected]!?A??.
解密后内容为：kale123456789
二、MD5
实现类：MD5.java
package com.kale.md5;
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public class MD5 {
/*
* MD5加密
*/
public static String getMD5Str(String str) {
MessageDigest messageDigest = null;
try {
messageDigest = MessageDigest.getInstance("MD5");
messageDigest.reset();
messageDigest.update(str.getBytes("UTF-8"));
} catch (NoSuchAlgorithmException e) {
System.out.println("NoSuchAlgorithmException caught!");
System.exit(-1);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
byte[] byteArray = messageDigest.digest();
StringBuffer md5StrBuff = new StringBuffer();
for (int i = 0; i < byteArray.length; i++) {
if (Integer.toHexString(0xFF & byteArray[i]).length() == 1)
md5StrBuff.append("0").append(Integer.toHexString(0xFF & byteArray[i]));
else
md5StrBuff.append(Integer.toHexString(0xFF & byteArray[i]));
}
//16位加密，从第9位到25位
return md5StrBuff.substring(8, 24).toString().toUpperCase();
}
}
测试类：Md5Test.java
package com.kale.md5;
public class Md5Test {
/**
* @param args
*/
public static void main(String[] args) {
String password = "123456789";
String result = MD5.getMD5Str(password);
System.out.println(result.toLowerCase());
}
}
结果：323b453885f5181f
三、RSA
实现类：RSA.java
package com.kale.rsa;
import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.RSAPrivateKeySpec;
import java.security.spec.RSAPublicKeySpec;
import java.util.HashMap;
import javax.crypto.Cipher;
public class RSA{
/**
* 生成公钥和私钥
* @throws NoSuchAlgorithmException
*
*/
public static HashMap<String, Object> getKeys() throws NoSuchAlgorithmException{
HashMap<String, Object> map = new HashMap<String, Object>();
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
keyPairGen.initialize(1024);
KeyPair keyPair = keyPairGen.generateKeyPair();
RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
map.put("public", publicKey);
map.put("private", privateKey);
return map;
}
/**
* 使用模和指数生成RSA公钥
* 注意：【此代码用了默认补位方式，为RSA/None/PKCS1Padding，不同JDK默认的补位方式可能不同，如Android默认是RSA
* /None/NoPadding】
*
* @param modulus
* 模
* @param exponent
* 指数
* @return
*/
public static RSAPublicKey getPublicKey(String modulus, String exponent) {
try {
BigInteger b1 = new BigInteger(modulus);
BigInteger b2 = new BigInteger(exponent);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
RSAPublicKeySpec keySpec = new RSAPublicKeySpec(b1, b2);
return (RSAPublicKey) keyFactory.generatePublic(keySpec);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
/**
* 使用模和指数生成RSA私钥
* 注意：【此代码用了默认补位方式，为RSA/None/PKCS1Padding，不同JDK默认的补位方式可能不同，如Android默认是RSA
* /None/NoPadding】
*
* @param modulus
* 模
* @param exponent
* 指数
* @return
*/
public static RSAPrivateKey getPrivateKey(String modulus, String exponent) {
try {
BigInteger b1 = new BigInteger(modulus);
BigInteger b2 = new BigInteger(exponent);
KeyFactory keyFactory = KeyFactory.getInstance("RSA");
RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec(b1, b2);
return (RSAPrivateKey) keyFactory.generatePrivate(keySpec);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
/**
* 公钥加密
*
* @param data
* @param publicKey
* @return
* @throws Exception
*/
public static String encryptByPublicKey(String data, RSAPublicKey publicKey)
throws Exception {
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
// 模长
int key_len = publicKey.getModulus().bitLength() / 8;
// 加密数据长度 <= 模长-11
String[] datas = splitString(data, key_len - 11);
String mi = "";
//如果明文长度大于模长-11则要分组加密
for (String s : datas) {
mi += bcd2Str(cipher.doFinal(s.getBytes()));
}
return mi;
}
/**
* 私钥解密
*
* @param data
* @param privateKey
* @return
* @throws Exception
*/
public static String decryptByPrivateKey(String data, RSAPrivateKey privateKey)
throws Exception {
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, privateKey);
//模长
int key_len = privateKey.getModulus().bitLength() / 8;
byte[] bytes = data.getBytes();
byte[] bcd = ASCII_To_BCD(bytes, bytes.length);
System.err.println(bcd.length);
//如果密文长度大于模长则要分组解密
String ming = "";
byte[][] arrays = splitArray(bcd, key_len);
for(byte[] arr : arrays){
ming += new String(cipher.doFinal(arr));
}
return ming;
}
/**
* ASCII码转BCD码
*
*/
public static byte[] ASCII_To_BCD(byte[] ascii, int asc_len) {
byte[] bcd = new byte[asc_len / 2];
int j = 0;
for (int i = 0; i < (asc_len + 1) / 2; i++) {
bcd[i] = asc_to_bcd(ascii[j++]);
bcd[i] = (byte) (((j >= asc_len) ? 0x00 : asc_to_bcd(ascii[j++])) + (bcd[i] << 4));
}
return bcd;
}
public static byte asc_to_bcd(byte asc) {
byte bcd;
if ((asc >= ‘0‘) && (asc <= ‘9‘))
bcd = (byte) (asc - ‘0‘);
else if ((asc >= ‘A‘) && (asc <= ‘F‘))
bcd = (byte) (asc - ‘A‘ + 10);
else if ((asc >= ‘a‘) && (asc <= ‘f‘))
bcd = (byte) (asc - ‘a‘ + 10);
else
bcd = (byte) (asc - 48);
return bcd;
}
/**
* BCD转字符串
*/
public static String bcd2Str(byte[] bytes) {
char temp[] = new char[bytes.length * 2], val;
for (int i = 0; i < bytes.length; i++) {
val = (char) (((bytes[i] & 0xf0) >> 4) & 0x0f);
temp[i * 2] = (char) (val > 9 ? val + ‘A‘ - 10 : val + ‘0‘);
val = (char) (bytes[i] & 0x0f);
temp[i * 2 + 1] = (char) (val > 9 ? val + ‘A‘ - 10 : val + ‘0‘);
}
return new String(temp);
}
/**
* 拆分字符串
*/
public static String[] splitString(String string, int len) {
int x = string.length() / len;
int y = string.length() % len;
int z = 0;
if (y != 0) {
z = 1;
}
String[] strings = new String[x + z];
String str = "";
for (int i=0; i<x+z; i++) {
if (i==x+z-1 && y!=0) {
str = string.substring(i*len, i*len+y);
}else{
str = string.substring(i*len, i*len+len);
}
strings[i] = str;
}
return strings;
}
/**
*拆分数组
*/
public static byte[][] splitArray(byte[] data,int len){
int x = data.length / len;
int y = data.length % len;
int z = 0;
if(y!=0){
z = 1;
}
byte[][] arrays = new byte[x+z][];
byte[] arr;
for(int i=0; i<x+z; i++){
arr = new byte[len];
if(i==x+z-1 && y!=0){
System.arraycopy(data, i*len, arr, 0, y);
}else{
System.arraycopy(data, i*len, arr, 0, len);
}
arrays[i] = arr;
}
return arrays;
}
}
测试类：RsaTest.java
package com.kale.rsa;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.util.HashMap;
public class RsaTest {
public static void main(String[] args) throws Exception {
// TODO Auto-generated method stub
HashMap<String, Object> map = RSA.getKeys();
//生成公钥和私钥
RSAPublicKey publicKey = (RSAPublicKey) map.get("public");
RSAPrivateKey privateKey = (RSAPrivateKey) map.get("private");
//模
String modulus = publicKey.getModulus().toString();
//公钥指数
String public_exponent = publicKey.getPublicExponent().toString();
//私钥指数
String private_exponent = privateKey.getPrivateExponent().toString();
//明文
String ming = "kale123456789";
//使用模和指数生成公钥和私钥
RSAPublicKey pubKey = RSA.getPublicKey(modulus, public_exponent);
RSAPrivateKey priKey = RSA.getPrivateKey(modulus, private_exponent);
//加密后的密文
String mi = RSA.encryptByPublicKey(ming, pubKey);
System.out.println(mi);
//解密后的明文
ming = RSA.decryptByPrivateKey(mi, priKey);
System.out.println(ming);
}
}
结果：
81169AA3AF3CEC80AAA685B0500A2BF058AB13BDEBA62A3D38AD382C444F66EC3DCA3C7E0225DF73C529EB94DDB978B761A87FB26518DEAC7FF85678BFB2B117B765E32E8E7A23864D2D69E9E351AA8FAA26F02F9964DA6275744833D7C8ABF2552DA83DBE66E682CE0592D3595220FAD9E4D56D849867135DE0CD3BDDFDCAF2
128
kale123456789
源码下载：http://download.csdn.net/detail/shark0017/8075485
时间： 2024-04-25 13:24:37