RSA前端JS加密，后端JAVA解密实现

用RSA非对称加密方式实现。后台生成rsa密钥对，然后在页面设置rsa公钥，提交时用公钥加密密码，生成的密文传到后台，后台再用私钥解密，获取密码明文。

这样客户端只需要知道rsa加密方式和公钥，前台不知道私钥是无法解密的，此解决方案还是相对比较安全的。

需要到http://www.bouncycastle.org下载bcprov-jdk16-140.jar文件。

缺陷：由于进行的都是大数计算，使得RSA最快的情况也比DES慢上100倍，无论
是软件还是硬件实现。所以一般来说只用于少 量数据 加密。

下面我们就来一个实际的例子：

1、前端加密需要引入Barrett.js、BigInt.js和RSA.js。

<script src="/rsa/RSA.js" type="text/javascript"></script>

<script src="/rsa/BigInt.js" type="text/javascript"></script>

<script src="/rsa/Barrett.js" type="text/javascript"></script>

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2、前端加密代码：

encryptedString : (function(paramStr, rsaKey){

setMaxDigits(130);

//第一个参数为加密指数、第二个参数为解密参数、第三个参数为加密系数

key = new RSAKeyPair("10001", "", rsaKey);

//返回加密后的字符串

return encryptedString(key, encodeURIComponent(paramStr));

})

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其中的加密系数可以自定义，这里为：8246a46f44fc4d961e139fd70f4787d272d374532f4d2d9b7cbaad6a15a8c1301319aa6b3f30413b859351c71938aec516fa7147b69168b195e81df46b6bed7950cf3a1c719d42175f73d7c97a85d7d20a9e83688b92f05b3059bb2ff75cd7190a042cd2db97ebc2ab4da366f2a7085556ed613b5a39c9fdd2bb2595d1dc23b5

3、后台RSA加密解密方法如下：

import java.io.ByteArrayOutputStream;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.math.BigInteger;

import java.security.KeyFactory;

import java.security.KeyPair;

import java.security.KeyPairGenerator;

import java.security.NoSuchAlgorithmException;

import java.security.PrivateKey;

import java.security.PublicKey;

import java.security.SecureRandom;

import java.security.interfaces.RSAPrivateKey;

import java.security.interfaces.RSAPublicKey;

import java.security.spec.InvalidKeySpecException;

import java.security.spec.RSAPrivateKeySpec;

import java.security.spec.RSAPublicKeySpec;

import javax.crypto.Cipher;

import org.apache.commons.lang.StringUtils;

import com.jd.uwp.common.Constants;

/**

* RSA 工具类。提供加密，解密，生成密钥对等方法。

* 需要bcprov-jdk16-140.jar包。

*

*/

public class RSAUtil {

private static String RSAKeyStore = "RSAKey.txt";

/**

* * 生成密钥对 *

* @return KeyPair *

* @throws EncryptException

*/

public static KeyPair generateKeyPair(String basePath) throws Exception {

try {

KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA",

new org.bouncycastle.jce.provider.BouncyCastleProvider());

//大小

final int KEY_SIZE = 1024;

keyPairGen.initialize(KEY_SIZE, new SecureRandom());

KeyPair keyPair = keyPairGen.generateKeyPair();

saveKeyPair(keyPair, basePath);

return keyPair;

} catch (Exception e) {

throw new Exception(e.getMessage());

}

}

/**

* 获取密钥对

* @return

* @throws Exception

*/

public static KeyPair getKeyPair(String basePath) throws Exception {

FileInputStream fis = new FileInputStream(StringUtils.isNotBlank(basePath) ? (basePath + RSAKeyStore) : RSAKeyStore);

ObjectInputStream oos = new ObjectInputStream(fis);

KeyPair kp = (KeyPair) oos.readObject();

oos.close();

fis.close();

return kp;

}

/**

* 保存密钥

* @param kp

* @throws Exception

*/

public static void saveKeyPair(KeyPair kp, String basePath) throws Exception {

FileOutputStream fos = new FileOutputStream(StringUtils.isNotBlank(basePath) ? (basePath + RSAKeyStore) : RSAKeyStore);

ObjectOutputStream oos = new ObjectOutputStream(fos);

// 生成密钥

oos.writeObject(kp);

oos.close();

fos.close();

}

/**

* * 生成公钥 *

* @param modulus *

* @param publicExponent *

* @return RSAPublicKey *

* @throws Exception

*/

public static RSAPublicKey generateRSAPublicKey(byte[] modulus,

byte[] publicExponent) throws Exception {

KeyFactory keyFac = null;

try {

keyFac = KeyFactory.getInstance("RSA",

new org.bouncycastle.jce.provider.BouncyCastleProvider());

} catch (NoSuchAlgorithmException ex) {

throw new Exception(ex.getMessage());

}

RSAPublicKeySpec pubKeySpec = new RSAPublicKeySpec(new BigInteger(

modulus), new BigInteger(publicExponent));

try {

return (RSAPublicKey) keyFac.generatePublic(pubKeySpec);

} catch (InvalidKeySpecException ex) {

throw new Exception(ex.getMessage());

}

}

/**

* * 生成私钥 *

* @param modulus *

* @param privateExponent *

* @return RSAPrivateKey *

* @throws Exception

*/

public static RSAPrivateKey generateRSAPrivateKey(byte[] modulus,

byte[] privateExponent) throws Exception {

KeyFactory keyFac = null;

try {

keyFac = KeyFactory.getInstance("RSA",

new org.bouncycastle.jce.provider.BouncyCastleProvider());

} catch (NoSuchAlgorithmException ex) {

throw new Exception(ex.getMessage());

}

RSAPrivateKeySpec priKeySpec = new RSAPrivateKeySpec(new BigInteger(

modulus), new BigInteger(privateExponent));

try {

return (RSAPrivateKey) keyFac.generatePrivate(priKeySpec);

} catch (InvalidKeySpecException ex) {

throw new Exception(ex.getMessage());

}

}

/**

* * 加密 *

* @param key

* 加密的密钥 *

* @param data

* 待加密的明文数据 *

* @return 加密后的数据 *

* @throws Exception

*/

public static byte[] encrypt(PublicKey pk, byte[] data) throws Exception {

try {

Cipher cipher = Cipher.getInstance("RSA",

new org.bouncycastle.jce.provider.BouncyCastleProvider());

cipher.init(Cipher.ENCRYPT_MODE, pk);

// 获得加密块大小，如：加密前数据为128个byte，而key_size=1024

int blockSize = cipher.getBlockSize();

// 加密块大小为127

// byte,加密后为128个byte;因此共有2个加密块，第一个127

// byte第二个为1个byte

int outputSize = cipher.getOutputSize(data.length);// 获得加密块加密后块大小

int leavedSize = data.length % blockSize;

int blocksSize = leavedSize != 0 ? data.length / blockSize + 1 : data.length / blockSize;

byte[] raw = new byte[outputSize * blocksSize];

int i = 0;

while (data.length - i * blockSize > 0) {

if (data.length - i * blockSize > blockSize) {

cipher.doFinal(data, i * blockSize, blockSize, raw, i * outputSize);

} else {

cipher.doFinal(data, i * blockSize, data.length - i * blockSize, raw, i * outputSize);

}

i++;

}

return raw;

} catch (Exception e) {

throw new Exception(e.getMessage());

}

}

/**

* * 解密 *

*

* @param key

* 解密的密钥 *

* @param raw

* 已经加密的数据 *

* @return 解密后的明文 *

* @throws Exception

*/

@SuppressWarnings("static-access")

public static byte[] decrypt(PrivateKey pk, byte[] raw) throws Exception {

try {

Cipher cipher = Cipher.getInstance("RSA", new org.bouncycastle.jce.provider.BouncyCastleProvider());

cipher.init(cipher.DECRYPT_MODE, pk);

int blockSize = cipher.getBlockSize();

ByteArrayOutputStream bout = new ByteArrayOutputStream(64);

int j = 0;

while (raw.length - j * blockSize > 0) {

bout.write(cipher.doFinal(raw, j * blockSize, blockSize));

j++;

}

return bout.toByteArray();

} catch (Exception e) {

throw new Exception(e.getMessage());

}

}

/**

* 解密方法

* paramStr ->密文

* basePath ->RSAKey.txt所在的文件夹路径

**/

public static String decryptStr(String paramStr, String basePath) throws Exception{

byte[] en_result = new BigInteger(paramStr, 16).toByteArray();

byte[] de_result = decrypt(getKeyPair(basePath).getPrivate(), en_result);

StringBuffer sb = new StringBuffer();

sb.append(new String(de_result));

//返回解密的字符串

return sb.reverse().toString();

}

}

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4、前端提交到后端解密调用:

//前端 表单提交

$.ajax({

url : contextPath + "test.action",

//加密传输

data : {pwd:encryptedString ($("#pwd").val(), "adasdasdasdasdadsasdasdasdasd")},

type : "post",

datatype : "json",

success : function(retData){

}

});

//后端解密代码

RSAUtil.decryptStr(paramMap.getString("pwd"), request.getSession().getServletContext().getRealPath("/"));

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