java加密之RSA加密

流程分析： 甲方构建密钥对儿，将公钥公布给乙方，将私钥保留。
甲方使用私钥加密数据，然后用私钥对加密后的数据签名，发送给乙方签名以及加密后的数据；乙方使用公钥、签名来验证待解密数据是否有效，如果有效使用公钥对数据解密。
乙方使用公钥加密数据，向甲方发送经过加密后的数据；甲方获得加密数据，通过私钥解密。

按如上步骤给出序列图，如下：

package com.rsa;

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;

/**
* 基础加密组件
*
* @author 梁栋
* @version 1.0
* @since 1.0
*/
@SuppressWarnings("restriction")
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.rsa;

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;

/**
* RSA安全编码组件
*
* @author 梁栋
* @version 1.0
* @since 1.0
*/
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);

// 构造PKCS8EncodedKeySpec对象
PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);

// KEY_ALGORITHM 指定的加密算法
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);

// 取私钥匙对象
PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);

// 用私钥对信息生成数字签名
Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
signature.initSign(priKey);
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 校验成功返回true 失败返回false
* @throws Exception
*
*/
public static boolean verify(byte[] data, String publicKey, String sign)
throws Exception {

// 解密由base64编码的公钥
byte[] keyBytes = decryptBASE64(publicKey);

// 构造X509EncodedKeySpec对象
X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);

// KEY_ALGORITHM 指定的加密算法
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);

// 取公钥匙对象
PublicKey pubKey = keyFactory.generatePublic(keySpec);

Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
signature.initVerify(pubKey);
signature.update(data);

// 验证签名是否正常
return signature.verify(decryptBASE64(sign));
}

/**
* 解密<br>
* 用私钥解密
*
* @param data
* @param key
* @return
* @throws Exception
*/
public static byte[] decryptByPrivateKey(byte[] data, String key)
throws Exception {
// 对密钥解密
byte[] keyBytes = decryptBASE64(key);

// 取得私钥
PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);

// 对数据解密
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.DECRYPT_MODE, privateKey);

return cipher.doFinal(data);
}

/**
* 解密<br>
* 用私钥解密
*
* @param data
* @param key
* @return
* @throws Exception
*/
public static byte[] decryptByPublicKey(byte[] data, String key)
throws Exception {
// 对密钥解密
byte[] keyBytes = decryptBASE64(key);

// 取得公钥
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
Key publicKey = keyFactory.generatePublic(x509KeySpec);

// 对数据解密
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.DECRYPT_MODE, publicKey);

return cipher.doFinal(data);
}

/**
* 加密<br>
* 用公钥加密
*
* @param data
* @param key
* @return
* @throws Exception
*/
public static byte[] encryptByPublicKey(byte[] data, String key)
throws Exception {
// 对公钥解密
byte[] keyBytes = decryptBASE64(key);

// 取得公钥
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
Key publicKey = keyFactory.generatePublic(x509KeySpec);

// 对数据加密
Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
cipher.init(Cipher.ENCRYPT_MODE, publicKey);

return cipher.doFinal(data);
}

/**
* 加密<br>
* 用私钥加密
*
* @param data
* @param key
* @return
* @throws Exception
*/
public static byte[] encryptByPrivateKey(byte[] data, String key)
throws Exception {
// 对密钥解密
byte[] keyBytes = decryptBASE64(key);

// 取得私钥
PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);

// 对数据加密
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 keyPairGen = KeyPairGenerator
.getInstance(KEY_ALGORITHM);
keyPairGen.initialize(1024);

KeyPair keyPair = keyPairGen.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(PUBLIC_KEY, publicKey);
keyMap.put(PRIVATE_KEY, privateKey);
return keyMap;
}
}

package com.rsa;

import static org.junit.Assert.*;

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

import java.util.Map;

/**
*
* @author 梁栋
* @version 1.0
* @since 1.0
*/
public class RSACoderTest {
private String publicKey;
private String privateKey;

@Before
public void setUp() throws Exception {
Map<String, Object> keyMap = RSACoder.initKey();

publicKey = RSACoder.getPublicKey(keyMap);
privateKey = RSACoder.getPrivateKey(keyMap);
System.err.println("公钥: \n\r" + publicKey);
System.err.println("私钥： \n\r" + privateKey);
}

@Test
public void test() throws Exception {
System.err.println("公钥加密——私钥解密");
String inputStr = "abc";
byte[] data = inputStr.getBytes();

byte[] encodedData = RSACoder.encryptByPublicKey(data, publicKey);

byte[] decodedData = RSACoder.decryptByPrivateKey(encodedData,
privateKey);

String outputStr = new String(decodedData);
System.err.println("加密前: " + inputStr + "\n\r" + "解密后: " + outputStr);
assertEquals(inputStr, outputStr);

}

@Test
public void testSign() throws Exception {
System.err.println("私钥加密——公钥解密");
String inputStr = "sign";
byte[] data = inputStr.getBytes();

byte[] encodedData = RSACoder.encryptByPrivateKey(data, privateKey);

byte[] decodedData = RSACoder
.decryptByPublicKey(encodedData, publicKey);

String outputStr = new String(decodedData);
System.err.println("加密前: " + inputStr + "\n\r" + "解密后: " + outputStr);
assertEquals(inputStr, outputStr);

System.err.println("私钥签名——公钥验证签名");
// 产生签名
String sign = RSACoder.sign(encodedData, privateKey);
System.err.println("签名:\r" + sign);

// 验证签名
boolean status = RSACoder.verify(encodedData, publicKey, sign);
System.err.println("状态:\r" + status);
assertTrue(status);

}

}