Java RSA 加解密

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.PKCS8EncodedKeySpec;
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);

           PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(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/PKCS1Padding");
           //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);

     }

}