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.interfaces.RSAPrivateKey;

　　import java.security.interfaces.RSAPublicKey;

　　import java.security.spec.CS8EncodedKeySpec;

　　import java.security.spec.X509EncodedKeySpec;

　　import javax.crypto.Cipher;

　　import sun.misc.BASE64Decoder;

　　import sun.misc.BASE64Encoder;

　　public class RSAHelper

　　/**

　　* 得到公钥

　　* @param key 密钥字符串(经过base64编码)

　　* @throws Exception

　　*/

　　public static PublicKey getPublicKey(String key) throws Exception {

　　byte[] keyBytes;

　　keyBytes = (new BASE64Decoder()).decodeBuffer(key);

　　X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);

　　KeyFactory keyFactory = KeyFactory.getInstance("RSA");

　　PublicKey publicKey = keyFactory.generatePublic(keySpec);

　　return publicKey;

　　}

　　/**

　　* 得到私钥

　　* @param key 密钥字符串(经过base64编码)

　　* @throws Exception

　　*/

　　public static PrivateKey getPrivateKey(String key) throws Exception {

　　byte[] keyBytes;

　　keyBytes = (new BASE64Decoder()).decodeBuffer(key);

　　CS8EncodedKeySpec keySpec = new CS8EncodedKeySpec(keyBytes);

　　KeyFactory keyFactory = KeyFactory.getInstance("RSA");

　　PrivateKey privateKey = keyFactory.generatePrivate(keySpec);

　　return privateKey;

　　}

　　/**

　　* 得到密钥字符串(经过base64编码)

　　* @return

　　*/

　　public static String getKeyString(Key key) throws Exception {

　　byte[] keyBytes = key.getEncoded();

　　String s = (new BASE64Encoder()).encode(keyBytes);

　　return s;

　　}

　　public static void main(String[] args) throws Exception {

　　KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");

　　//密钥位数

　　keyPairGen.initialize(1024);

　　//密钥对

　　KeyPair keyPair = keyPairGen.generateKeyPair();

　　// 公钥

　　PublicKey publicKey = (RSAPublicKey) keyPair.getPublic();

　　// 私钥

　　PrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();

　　String publicKeyString = getKeyString(publicKey);

　　System.out.println("public:n" + publicKeyString);

　　String privateKeyString = getKeyString(privateKey);

　　System.out.println("private:n" + privateKeyString);

　　//加解密类

　　Cipher cipher = Cipher.getInstance("RSA");//Cipher.getInstance("RSA/ECB/CS1Padding");

　　//明文

　　byte[] plainText = "我们都很好!邮件：@sina.com".getBytes();

　　//加密

　　cipher.init(Cipher.ENCRYPT_MODE, publicKey);

　　byte[] enBytes = cipher.doFinal(plainText);

　　//通过密钥字符串得到密钥

　　publicKey = getPublicKey(publicKeyString);

　　privateKey = getPrivateKey(privateKeyString);

　　//解密

　　cipher.init(Cipher.DECRYPT_MODE, privateKey);

　　byte[]deBytes = cipher.doFinal(enBytes);

　　publicKeyString = getKeyString(publicKey);

　　System.out.println("public:n" +publicKeyString);

　　privateKeyString = getKeyString(privateKey);

　　System.out.println("private:n" + privateKeyString);

　　String s = new String(deBytes);

　　System.out.println(s);

　　}

　　通过modulus public exponent private exponent生成 RSA Key

　　import java.math.BigInteger;

　　import java.security.KeyFactory;

　　import java.security.PrivateKey;

　　import java.security.PublicKey;

　　import java.security.spec.RSAPrivateKeySpec;

　　import java.security.spec.RSAPublicKeySpec;

　　import javax.crypto.Cipher;

　　public class RsaKey {

　　public PublicKey getPublicKey(String modulus,String publicExponent) throws Exception {

　　BigInteger m = new BigInteger(modulus);

　　BigInteger e = new BigInteger(publicExponent);

　　RSAPublicKeySpec keySpec = new RSAPublicKeySpec(m,e);

　　KeyFactory keyFactory = KeyFactory.getInstance("RSA");

　　PublicKey publicKey = keyFactory.generatePublic(keySpec);

　　return publicKey;

　　}

　　public PrivateKey getPrivateKey(String modulus,String privateExponent) throws Exception {

　　BigInteger m = new BigInteger(modulus);

　　BigInteger e = new BigInteger(privateExponent);

　　RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec(m,e);

　　KeyFactory keyFactory = KeyFactory.getInstance("RSA");

　　PrivateKey privateKey = keyFactory.generatePrivate(keySpec);

　　return privateKey;

　　}

　　public static void main(String[] args) throws Exception {

　　String modulus = "10103166745709600780215616551837697832816413714471062522342538060943596036859967333870827790358555455232243383580565187280643159050869924436081447583051139";

　　String publicExponent = "65537";

　　String privateExponet = "367979294475011322800474185715497882523349856362702385535371444397399388741997039894583483410120364529325888461124714276674612930833020362278754665756193";

　　RsaKey key = new RsaKey();

　　PublicKey publicKey = key.getPublicKey(modulus, publicExponent);

　　PrivateKey privateKey = key.getPrivateKey(modulus, privateExponet);

　　//加解密类

　　Cipher cipher = Cipher.getInstance("RSA");

　　//明文

　　byte[] plainText = "我们都很好!邮件：@sina.com".getBytes();

　　//加密

　　cipher.init(Cipher.ENCRYPT_MODE, publicKey);

　　byte[] enBytes = cipher.doFinal(plainText);

　　cipher.init(Cipher.DECRYPT_MODE, privateKey);

　　byte[]deBytes = cipher.doFinal(enBytes);

　　String s = new String(deBytes);

　　System.out.println(s);

　　}