RSA算法的Java实现及Base64的正确使用

遇到的问题：
    今天参考他人代码实现了一下RSA算法。遇到一个问题，网上的RSA工具类中的核心方法大多是需要传入byte[]数组进行处理，而不能直接传入String进行处理，这里对byte[]的处理部分进行了完全的封装，使用户的传入参数完全String化。大大简化了工具类的使用。

    这其中关键是需要用到Base64对String和byte[]进行互转。

Base64的jar包下载地址：http://download.csdn.net/detail/ldld1717/9772776

核心代码：

package RSARSA;import java.security.KeyFactory;import java.security.KeyPair;import java.security.KeyPairGenerator;import java.security.PrivateKey;import java.security.PublicKey;import java.security.SecureRandom;import java.security.Signature;import java.security.spec.PKCS8EncodedKeySpec;import java.security.spec.X509EncodedKeySpec;import java.util.HashMap;import java.util.Map;import javax.crypto.Cipher;import org.apache.commons.codec.binary.Base64;public class RSATest {// 数字签名，密钥算法private static final String RSA_KEY_ALGORITHM = "RSA";// 数字签名签名/验证算法private static final String SIGNATURE_ALGORITHM = "MD5withRSA";// RSA密钥长度private static final int KEY_SIZE = 1024;private static final String PUBLIC_KEY = "publicKey";private static final String PRIVATE_KEY = "privateKey";/** * 初始化RSA密钥对 * @return RSA密钥对 * @throws Exception 抛出异常 */private static Map<String, String> initKey() throws Exception {KeyPairGenerator keygen = KeyPairGenerator.getInstance(RSA_KEY_ALGORITHM);SecureRandom secrand = new SecureRandom();secrand.setSeed("hahaha".getBytes());// 初始化随机产生器keygen.initialize(KEY_SIZE, secrand); // 初始化密钥生成器KeyPair keys = keygen.genKeyPair();String pub_key = Base64.encodeBase64String(keys.getPublic().getEncoded());String pri_key = Base64.encodeBase64String(keys.getPrivate().getEncoded());Map<String, String> keyMap = new HashMap<String, String>();keyMap.put(PUBLIC_KEY, pub_key);keyMap.put(PRIVATE_KEY, pri_key);System.out.println("公钥：" + pub_key);System.out.println("私钥：" + pri_key);return keyMap;}    /**     * 得到公钥     * @param keyMap RSA密钥对     * @return 公钥     * @throws Exception 抛出异常     */public static String getPublicKey(Map<String, String> keyMap) throws Exception{return keyMap.get(PUBLIC_KEY);}/** * 得到私钥 * @param keyMap RSA密钥对 * @return 私钥 * @throws Exception 抛出异常 */public static String getPrivateKey(Map<String, String> keyMap) throws Exception{return keyMap.get(PRIVATE_KEY);}/** * 数字签名 * @param data 待签名数据 * @param pri_key 私钥 * @return 签名 * @throws Exception 抛出异常 */public static String sign(byte[] data, String pri_key) throws Exception {// 取得私钥byte[] pri_key_bytes = Base64.decodeBase64(pri_key);PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(pri_key_bytes);KeyFactory keyFactory = KeyFactory.getInstance(RSA_KEY_ALGORITHM);// 生成私钥PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);// 实例化SignatureSignature signature = Signature.getInstance(SIGNATURE_ALGORITHM);// 初始化Signaturesignature.initSign(priKey);// 更新signature.update(data);return Base64.encodeBase64String(signature.sign());}/** * RSA校验数字签名 * @param data 数据 * @param sign 签名 * @param pub_key 公钥 * @return 校验结果，成功为true，失败为false * @throws Exception 抛出异常 */public boolean verify(byte[] data, byte[] sign, String pub_key) throws Exception {// 转换公钥材料// 实例化密钥工厂byte[] pub_key_bytes = Base64.decodeBase64(pub_key);KeyFactory keyFactory = KeyFactory.getInstance(RSA_KEY_ALGORITHM);// 初始化公钥// 密钥材料转换X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(pub_key_bytes);// 产生公钥PublicKey pubKey = keyFactory.generatePublic(x509KeySpec);// 实例化SignatureSignature signature = Signature.getInstance(SIGNATURE_ALGORITHM);// 初始化Signaturesignature.initVerify(pubKey);// 更新signature.update(data);// 验证return signature.verify(sign);}/** * 公钥加密 * @param data 待加密数据 * @param pub_key 公钥 * @return 密文 * @throws Exception 抛出异常 */private static byte[] encryptByPubKey(byte[] data, byte[] pub_key) throws Exception {// 取得公钥X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(pub_key);KeyFactory keyFactory = KeyFactory.getInstance(RSA_KEY_ALGORITHM);PublicKey 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);}/** * 公钥加密 * @param data 待加密数据 * @param pub_key 公钥 * @return 密文 * @throws Exception 抛出异常 */public static String encryptByPubKey(String data, String pub_key) throws Exception {// 私匙加密byte[] pub_key_bytes = Base64.decodeBase64(pub_key);byte[] enSign = encryptByPubKey(data.getBytes(), pub_key_bytes);return Base64.encodeBase64String(enSign);}/** * 私钥加密 * @param data 待加密数据 * @param pri_key 私钥 * @return 密文 * @throws Exception 抛出异常 */private static byte[] encryptByPriKey(byte[] data, byte[] pri_key) throws Exception {// 取得私钥PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(pri_key);KeyFactory keyFactory = KeyFactory.getInstance(RSA_KEY_ALGORITHM);PrivateKey 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);}/** * 私钥加密 * @param data 待加密数据 * @param pri_key 私钥 * @return 密文 * @throws Exception 抛出异常 */public static String encryptByPriKey(String data, String pri_key) throws Exception {// 私匙加密byte[] pri_key_bytes = Base64.decodeBase64(pri_key);byte[] enSign = encryptByPriKey(data.getBytes(), pri_key_bytes);return Base64.encodeBase64String(enSign);}/** * 公钥解密 * @param data 待解密数据 * @param pub_key 公钥 * @return 明文 * @throws Exception 抛出异常 */private static byte[] decryptByPubKey(byte[] data, byte[] pub_key) throws Exception {// 取得公钥X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(pub_key);KeyFactory keyFactory = KeyFactory.getInstance(RSA_KEY_ALGORITHM);PublicKey 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);}/** * 公钥解密 * @param data 待解密数据 * @param pub_key 公钥 * @return 明文 * @throws Exception 抛出异常 */public static String decryptByPubKey(String data, String pub_key) throws Exception {// 公匙解密byte[] pub_key_bytes = Base64.decodeBase64(pub_key);byte[] design = decryptByPubKey(Base64.decodeBase64(data), pub_key_bytes);return new String(design);}/** * 私钥解密 * @param data 待解密数据 * @param pri_key 私钥 * @return 明文 * @throws Exception 抛出异常 */private static byte[] decryptByPriKey(byte[] data, byte[] pri_key) throws Exception {// 取得私钥PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(pri_key);KeyFactory keyFactory = KeyFactory.getInstance(RSA_KEY_ALGORITHM);PrivateKey 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);}/** * 私钥解密 * @param data 待解密数据 * @param pri_key 私钥 * @return 明文 * @throws Exception 抛出异常 */public static String decryptByPriKey(String data, String pri_key) throws Exception {// 私匙解密byte[] pri_key_bytes = Base64.decodeBase64(pri_key);byte[] design = decryptByPriKey(Base64.decodeBase64(data), pri_key_bytes);return new String(design);}/** * @param args */@SuppressWarnings("static-access")public static void main(String[] args) throws Exception {RSATest das = new RSATest();String datastr = "天街小雨润如酥，草色遥看近却无。最是一年春好处，绝胜烟柳满皇都。";System.out.println("待加密数据：\n" + datastr);//获取密钥对Map<String, String> keyMap = new HashMap<String, String>();keyMap = das.initKey();String pub_key = (String) keyMap.get(PUBLIC_KEY);String pri_key = (String) keyMap.get(PRIVATE_KEY);// 公匙加密String pubKeyStr = RSATest.encryptByPubKey(datastr, pub_key);System.out.println("公匙加密结果：\n" + pubKeyStr);// 私匙解密String priKeyStr = RSATest.decryptByPriKey(pubKeyStr, pri_key);System.out.println("私匙解密结果：\n" + priKeyStr);//换行System.out.println();// 数字签名String str1 = "汉兵已略地";String str2 = "四面楚歌声";System.out.println("正确的签名：" + str1 + "\n错误的签名：" + str2);String sign = RSATest.sign(str1.getBytes(), pri_key);System.out.println("数字签名：\n" + sign);boolean vflag1 = das.verify(str1.getBytes(), Base64.decodeBase64(sign), pub_key);System.out.println("数字签名验证结果1：\n" + vflag1);boolean vflag2 = das.verify(str2.getBytes(), Base64.decodeBase64(sign), pub_key);System.out.println("数字签名验证结果2：\n" + vflag2);}}

这其中有必要对Base64的用法做一点提炼:

    1.byte[]转为String用到Base64.encodeBase64String(传待转的byte数组)方法;

    2.String转byte[]用到Base64.decodeBase64(传待转的字符串)方法;

    3.以上两步若实现byte[]--->-String-->byte[]，则byte[]不变，也不会有乱码，所以Base64还是非常好用的。

实验结果：

实验结果完全符合预期。