JAVA实现RSA加密解密

RSA 工具类。提供加密，解密，生成密钥对等方法。

RSA加密原理概述   ：

RSA的安全性依赖于大数的分解，公钥和私钥都是两个大素数（大于100的十进制位）的函数。

据猜测，从一个密钥和密文推断出明文的难度等同于分解两个大素数的积

密钥的产生：

1.选择两个大素数 p,q ,计算 n=p*q;

2.随机选择加密密钥 e ,要求 e 和 (p-1)*(q-1)互质

3.利用 Euclid 算法计算解密密钥 d , 使其满足 e*d = 1(mod(p-1)*(q-1)) (其中 n,d 也要互质)

4:至此得出公钥为 (n,e) 私钥为 (n,d)

RSA速度

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。

速度一直是RSA的缺陷。一般来说只用于少量数据 加密。

package com.security.rsa;

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;
public class RSAsecurity {

public static String src="RSA 加密字符串";
public void priENpubDE() {

    try {
      //1.初始化秘钥
     KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
     //秘钥长度
     keyPairGenerator.initialize(512);
     //初始化秘钥对
     KeyPair keyPair = keyPairGenerator.generateKeyPair();
     //公钥
     RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
     //私钥
     RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();

    //2.私钥加密，公钥解密----加密
     //生成私钥
     PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
     KeyFactory keyFactory =KeyFactory.getInstance("RSA");
     PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
     //Cipher类为加密和解密提供密码功能，通过getinstance实例化对象
     Cipher cipher =Cipher.getInstance("RSA");
     //初始化加密
     cipher.init(Cipher.ENCRYPT_MODE,privateKey);
     byte[] result = cipher.doFinal(src.getBytes());
     System.out.println("私钥加密，公钥解密----加密:"+Base64.encode(result));

     //3.私钥加密，公钥解密----解密
     //生成公钥
     X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());
     keyFactory=KeyFactory.getInstance("RSA");
     PublicKey publicKey= keyFactory.generatePublic(x509EncodedKeySpec);
     cipher = Cipher.getInstance("RSA");
     //初始化解密
     cipher.init(Cipher.DECRYPT_MODE,publicKey);
     result = cipher.doFinal(result);
     System.out.println("私钥加密，公钥解密----解密:"+new String(result));
    } catch (Exception e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
 }

}

   public void pubENpriDE() {

       try {
         //1.初始化秘钥
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
        //秘钥长度
        keyPairGenerator.initialize(512);
        //初始化秘钥对
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        //公钥
        RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
        //私钥
        RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();

        //2.公钥加密，私钥解密----加密
       X509EncodedKeySpec x509EncodedKeySpec=new X509EncodedKeySpec(rsaPublicKey.getEncoded());
    KeyFactory keyFactory = KeyFactory.getInstance("RSA");
    PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
     //初始化加密
    //Cipher类为加密和解密提供密码功能，通过getinstance实例化对象
    Cipher cipher =Cipher.getInstance("RSA");
    cipher.init(Cipher.ENCRYPT_MODE,publicKey);
     //加密字符串
    byte[] result = cipher.doFinal(src.getBytes());
     System.out.println("公钥加密，私钥解密----加密:"+Base64.encode(result));

     //3.公钥加密，私钥解密-----解密
   PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
     keyFactory=KeyFactory.getInstance("RSA");
   PrivateKey  privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
     //初始化解密
     cipher.init(Cipher.DECRYPT_MODE, privateKey);
     //解密字符串
     result = cipher.doFinal(result);
     System.out.println("公钥加密，私钥解密-----解密:"+new String(result));

       } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

}
}

测试：

package com.secutiry.rsa;

import com.security.rsa.RSAsecurity;

public class RSAtest {
public static void main(String[] args) {
    RSAsecurity rsAsecurity = new RSAsecurity();
    System.out.println("私钥加密公钥解密例：");
    rsAsecurity.priENpubDE();
    System.out.println("公钥加密私钥解密例：");
    rsAsecurity.pubENpriDE();

}
}

测试结果：

源代码 下载地址

http://download.csdn.net/download/u013400939/8517989点击打开链接