JAVA 非对称加密算法RSA

非对称加密算法 RSA过程 ： 以甲乙双方为例
　　1、初始化密钥 构建密钥对,生成公钥、私钥保存到keymap中
　　　　KeyPairGenerator ---> KeyPair --> RSAPublicKey、RSAPrivateKey
　　2、甲方使用私钥加密, 加密后在用私钥对加密数据进行数据签名，然后发送给乙方
　　　　RSACoder.encryptByPrivateKey(data, privateKey);
　　　　RSACoder.sign(encodedData, privateKey);
　　3、乙方则通过公钥验证签名的加密数据，如果验证正确则在通过公钥对加密数据进行解密
　　　　RSACoder.verify(encodedData, publicKey, sign);
　　　　RSACoder.decryptByPublicKey(encodedData, publicKey);
　　 4、乙方在通过公钥加密发送给甲方
　　　　RSACoder.encryptByPublicKey(decodedData, publicKey);
　　5、甲方通过私钥解密该数据
　　　　RSACoder.decryptPrivateKey(encodedData, privateKey);
流程图如下：

java代码实现如下：

package com.bank.utils;

import java.security.MessageDigest;

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

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

public abstract class Coder {
	public static final String KEY_SHA = "SHA";
	public static final String KEY_MD5 = "MD5";
	
	/** 
     * MAC算法可选以下多种算法 
     *  
     * <pre> 
     * HmacMD5  
     * HmacSHA1  
     * HmacSHA256  
     * HmacSHA384  
     * HmacSHA512 
     * </pre> 
     */  
	public static final String KEY_MAC = "HmacMD5";
	
	/**
	 * BASE64解密
	 * @param key
	 * @return
	 * @throws Exception
	 */
	public static byte[] decryptBASE64( String key ) throws Exception{
		return (new BASE64Decoder()).decodeBuffer(key);
	}
	
	/**
	 * BASE64加密
	 * @param key
	 * @return
	 * @throws Exception
	 */
	public static String encryptBASE64( byte[] key) throws Exception{
		return (new BASE64Encoder()).encodeBuffer(key);
	}
	
	/**
	 * MD5 加密
	 * @param data
	 * @return
	 * @throws Exception
	 */
	public static byte[] encryptMD5( byte[] data) throws Exception {
		MessageDigest md5 = MessageDigest.getInstance(KEY_MD5);
		md5.update(data);
		
		return md5.digest();
	}
	
	/**
	 * SHA 加密
	 * @param data
	 * @return
	 * @throws Exception
	 */
	public static byte[] encryptSHA( byte[] data) throws Exception {
		MessageDigest sha = MessageDigest.getInstance(KEY_SHA);
		sha.update(data);
		
		return sha.digest();
	}
	
	/** 
     * 初始化HMAC密钥 
     *  
     * @return 
     * @throws Exception 
     */  
	public static String initMacKey() throws Exception{
		KeyGenerator keyGenerator = KeyGenerator.getInstance(KEY_MAC);
		
		SecretKey secretKey = keyGenerator.generateKey();
		return encryptBASE64(secretKey.getEncoded());
	}
	
	/**
	 * HMAC  加密
	 * @param data
	 * @param key
	 * @return
	 * @throws Exception
	 */
	public static byte[] encryptHMAC( byte[] data, String key) throws Exception{
		SecretKey secretKey = new SecretKeySpec(decryptBASE64(key), KEY_MAC);
		Mac mac = Mac.getInstance(secretKey.getAlgorithm());
		mac.init(secretKey);
		return mac.doFinal(data);
	}
}

　　

package com.bank.utils;

import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

import javax.crypto.Cipher;


public abstract class RSACoder extends Coder{
	public static final String KEY_ALGORITHM = "RSA";
	public static final String SIGNATURE_ALGORITHM = "MD5withRSA";
	
	private static final String PUBLIC_KEY = "RSAPublicKey";
	private static final String PRIVATE_KEY = "RSAPrivatekey";
	
	/**
	 * 用私钥对信息生成数字签名
	 * @param data 加密数据
	 * @param privateKey 私钥
	 * @return
	 * @throws Exception
	 */
	public static String sign(byte[] data, String privateKey) throws Exception {
		//解密由base64编码的私钥
		byte[] keyBytes = decryptBASE64(privateKey);
		
		PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(keyBytes);
		
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		
		//取私钥对象
		PrivateKey pKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
		
		//用私钥生成数字签名
		Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
		signature.initSign(pKey);
		signature.update(data);
		
		return encryptBASE64(signature.sign());
	}
	
	/**
	 * 校验数字签名
	 * @param data 加密数据
	 * @param publicKey 公钥
	 * @param sign 数字签名
	 * @return
	 * @throws Exception
	 */
	public static boolean verify(byte[] data, String publicKey, String sign) throws Exception{
		
		//解密有base64编码的公钥
		byte[] keyBytes = decryptBASE64(publicKey);
		
		X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
		
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		
		//取公钥对象
		PublicKey pKey = keyFactory.generatePublic(keySpec);
		
		Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
		signature.initVerify(pKey);
		signature.update(data);
		//验证签名是否正常
		return signature.verify(decryptBASE64(sign));
	}
	
	/**
	 * 解密 
	 * 	用私钥解密
	 * @param data 加密数据
	 * @param key
	 * @return
	 * @throws Exception
	 */
	public static byte[] decryptPrivateKey(byte[] data, String key) throws Exception{
		byte[] keyBytes = decryptBASE64(key);
		
		//取得私钥
		PKCS8EncodedKeySpec encodedKeySpec = new PKCS8EncodedKeySpec(keyBytes);
		KeyFactory factory = KeyFactory.getInstance(KEY_ALGORITHM);
		Key pKey = factory.generatePrivate(encodedKeySpec);
		
		//对数据解密
		Cipher cipher = Cipher.getInstance(factory.getAlgorithm());
		cipher.init(Cipher.DECRYPT_MODE, pKey);
		
		return cipher.doFinal(data);
	}
	
	/**
	 * 用公钥解密
	 * @param data
	 * @param key
	 * @return
	 * @throws Exception
	 */
	public static byte[] decryptByPublicKey( byte[] data, String key) throws Exception{
		
		//解密
		byte[] keyBytes = decryptBASE64(key);
		
		//取得公钥
		X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		Key pKey = keyFactory.generatePublic(keySpec);
		
		//对数据解密
		Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
		cipher.init(Cipher.DECRYPT_MODE, pKey);
		
		return cipher.doFinal(data);
	}
	
	/**
	 * 用公钥加密
	 * @param data
	 * @param key
	 * @return
	 * @throws Exception
	 */
	public static byte[] encryptByPublicKey( byte[] data, String key) throws Exception{
		
		byte[] keyBytes = decryptBASE64(key);
		
		X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		Key pKey = keyFactory.generatePublic(keySpec);
		
		
		Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
		cipher.init(Cipher.ENCRYPT_MODE, pKey);
		
		return cipher.doFinal(data);
	}
	
	/**
	 * 用私钥加密
	 * @param data
	 * @param key
	 * @return
	 * @throws Exception
	 */
	public static byte[] encryptByPrivateKey(byte[] data, String key) throws Exception{
		
		byte[] keyBytes = decryptBASE64(key);
		
		PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		Key privateKey = keyFactory.generatePrivate(keySpec);
		
		Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
		cipher.init(Cipher.ENCRYPT_MODE, privateKey);
		
		return cipher.doFinal(data);
	}
	
	/**
	 * 取得私钥
	 * @param keyMap
	 * @return
	 * @throws Exception
	 */
	public static String getPrivateKey( Map<String, Object> keyMap) throws Exception{

		Key key = (Key) keyMap.get(PRIVATE_KEY);
		
		return encryptBASE64(key.getEncoded());
	}
	
	/**
	 * 取得公钥
	 * @param keyMap
	 * @return
	 * @throws Exception
	 */
	public static String getPublicKey( Map<String, Object> keyMap) throws Exception{

		Key key = (Key) keyMap.get(PUBLIC_KEY);
		
		return encryptBASE64(key.getEncoded());
	}
	/**
	 * 初始化密钥
	 * @return
	 * @throws Exception
	 */
	public static Map<String, Object> initKey() throws Exception{
		
		KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(KEY_ALGORITHM);
		keyPairGenerator.initialize(1024);
		
		KeyPair keyPair = keyPairGenerator.generateKeyPair();
		//公钥
		RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
		
		//私钥
		RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
		
		Map<String, Object> keyMap = new HashMap<String, Object>(2);
		keyMap.put(PRIVATE_KEY, privateKey);
		keyMap.put(PUBLIC_KEY, publicKey);
		return keyMap;
	}
}

　　

package com.bank.test;

import java.util.Map;

import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;

import com.bank.utils.RSACoder;

public class RSACoderTest {
	private String publicKey;
	private String privateKey;
	/*
	 * 非对称加密算法   RSA过程 ： 以甲乙双方为例
	 * 		1、初始化密钥 构建密钥对,生成公钥、私钥保存到keymap中
	 * 				KeyPairGenerator --->	KeyPair		-->		RSAPublicKey、RSAPrivateKey
	 * 		2、甲方使用私钥加密, 加密后在用私钥对加密数据进行数据签名，然后发送给乙方
	 * 				RSACoder.encryptByPrivateKey(data, privateKey);
	 * 				RSACoder.sign(encodedData, privateKey);
	 * 		3、乙方则通过公钥验证签名的加密数据，如果验证正确则在通过公钥对加密数据进行解密
	 * 				RSACoder.verify(encodedData, publicKey, sign);
	 * 				RSACoder.decryptByPublicKey(encodedData, publicKey);				
	 * 
	 * 		4、乙方在通过公钥加密发送给甲方
	 * 				RSACoder.encryptByPublicKey(decodedData, publicKey);
	 * 		5、甲方通过私钥解密该数据		
	 * 				RSACoder.decryptPrivateKey(encodedData, privateKey);				
	 */
	@Before
	public void setUp() throws Exception {
		
		Map<String , Object> keyMap = RSACoder.initKey();
		
		publicKey = RSACoder.getPublicKey(keyMap);
		privateKey = RSACoder.getPrivateKey(keyMap);
		
		System.out.println("公钥：
" + publicKey);
		System.out.println("私钥：
" + privateKey);
	}
	@Test
	public void test() throws Exception{
		String inputStr = "abc";
		byte[] data = inputStr.getBytes();//每次的得到的字节数组是不一样的。
		//第二步 私钥加密
		byte[] encodedData = RSACoder.encryptByPrivateKey(data, privateKey);
		//私钥进行数据签名
		String sign = RSACoder.sign(encodedData, privateKey);
		
		//第三步 公钥验证数字签名
		boolean flag = RSACoder.verify(encodedData, publicKey, sign);
		System.out.println("flag:" + flag);
		//用公钥对数据解密
		byte[] decodedData = RSACoder.decryptByPublicKey(encodedData, publicKey);
		
		System.out.println("data:" + data + "加密数据：" + encodedData + "    解密数据：" + decodedData);
		System.out.println("加密前数据-：" + new String(data) + "     解密后数据： " + new String(decodedData));
		
		//第四步使用公钥加密数据
		encodedData = RSACoder.encryptByPublicKey(decodedData, publicKey);
		
		//第五步 使用私钥解密数据
		decodedData = RSACoder.decryptPrivateKey(encodedData, privateKey);
		
		
		System.out.println("data:" + data + "加密数据：" + encodedData + "    解密数据：" + decodedData);
		System.out.println("加密前数据：" + inputStr + "     解密后数据： " + new String(decodedData));
	}
	
	
	@Test
	public void test1() throws Exception{
		System.out.println("私钥加密-----公钥解密");
		String inputStr = "abc";
		byte[] data = inputStr.getBytes();
		System.out.println("data:" + data);
		
		byte[] encodedData = RSACoder.encryptByPrivateKey(data, privateKey);
		byte[] decodedData = RSACoder.decryptByPublicKey(encodedData, publicKey);
	
		String outputStr = new String( decodedData );
		
		System.out.println("加密前：" + inputStr +"
 解密后：" + outputStr);
		
		Assert.assertEquals(inputStr, outputStr);
		
		
		System.out.println("私钥签名---公钥验证签名");
		//产生签名
		String sign = RSACoder.sign(encodedData, privateKey);
		System.out.println("签名：
" + sign);
		
		//验证签名
		boolean flag = RSACoder.verify(encodedData, publicKey, sign);
		
		System.out.println("状态：
" + flag);
		
		Assert.assertTrue(flag);
	}
}