非对称加密算法

RSA是一种公钥密码算法，RSA算法属于非对称加密算法。它由三位数学家Rivest、Shamir和Adleman共同发明，并以他们名字的首字母命名。与非对称加密算法不同，对称加密算法使用相同的密钥进行加密和解密。RSA算法的特点是使用一对密钥，即公钥和私钥，其中公钥用于加密数据，而私钥用于解密数据。由于RSA算法在加密运算时速度较慢，它通常用于信息量较小的加密场合。

java实现RSA的简单加密解密

RSAUtil 

package com.zhuyun.rsa;
 
import java.io.IOException;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
 
import javax.crypto.Cipher;
 
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
 
public class RSAUtil {
    //生成秘钥对
    public static KeyPair getKeyPair() throws Exception {
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
        keyPairGenerator.initialize(2048);
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
        return keyPair;
    }
    
    //获取公钥(Base64编码)
    public static String getPublicKey(KeyPair keyPair){
        PublicKey publicKey = keyPair.getPublic();
        byte[] bytes = publicKey.getEncoded();
        return byte2Base64(bytes);
    }
    
    //获取私钥(Base64编码)
    public static String getPrivateKey(KeyPair keyPair){
        PrivateKey privateKey = keyPair.getPrivate();
        byte[] bytes = privateKey.getEncoded();
        return byte2Base64(bytes);
    }
    
    //将Base64编码后的公钥转换成PublicKey对象
    public static PublicKey string2PublicKey(String pubStr) throws Exception{
        byte[] keyBytes = base642Byte(pubStr);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey publicKey = keyFactory.generatePublic(keySpec);
        return publicKey;
    }
    
    //将Base64编码后的私钥转换成PrivateKey对象
    public static PrivateKey string2PrivateKey(String priStr) throws Exception{
        byte[] keyBytes = base642Byte(priStr);
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
        return privateKey;
    }
    
    //公钥加密
    public static byte[] publicEncrypt(byte[] content, PublicKey publicKey) throws Exception{
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] bytes = cipher.doFinal(content);
        return bytes;
    }
    
    //私钥解密
    public static byte[] privateDecrypt(byte[] content, PrivateKey privateKey) throws Exception{
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        byte[] bytes = cipher.doFinal(content);
        return bytes;
    }
    
    //字节数组转Base64编码
    public static String byte2Base64(byte[] bytes){
        BASE64Encoder encoder = new BASE64Encoder();
        return encoder.encode(bytes);
    }
    
    //Base64编码转字节数组
    public static byte[] base642Byte(String base64Key) throws IOException{
        BASE64Decoder decoder = new BASE64Decoder();
        return decoder.decodeBuffer(base64Key);
    }
}

TestRSA 

package com.zhuyun.test;
 
import java.security.KeyPair;
import java.security.PrivateKey;
import java.security.PublicKey;
 
import org.junit.Test;
 
import com.zhuyun.rsa.RSAUtil;
 
public class TestRSA {
 
    @Test
    public void testRSA(){
        try {
            //===============生成公钥和私钥，公钥传给客户端，私钥服务端保留==================
            //生成RSA公钥和私钥，并Base64编码
            KeyPair keyPair = RSAUtil.getKeyPair();
            String publicKeyStr = RSAUtil.getPublicKey(keyPair);
            String privateKeyStr = RSAUtil.getPrivateKey(keyPair);
            System.out.println("RSA公钥Base64编码:" + publicKeyStr);
            System.out.println("RSA私钥Base64编码:" + privateKeyStr);
            
            //=================客户端=================
            //hello, i am infi, good night!加密
            String message = "hello, i am infi, good night!";
            //将Base64编码后的公钥转换成PublicKey对象
            PublicKey publicKey = RSAUtil.string2PublicKey(publicKeyStr);
            //用公钥加密
            byte[] publicEncrypt = RSAUtil.publicEncrypt(message.getBytes(), publicKey);
            //加密后的内容Base64编码
            String byte2Base64 = RSAUtil.byte2Base64(publicEncrypt);
            System.out.println("公钥加密并Base64编码的结果：" + byte2Base64);
            
            
            //##############    网络上传输的内容有Base64编码后的公钥 和 Base64编码后的公钥加密的内容     #################
            
            
            
            //===================服务端================
            //将Base64编码后的私钥转换成PrivateKey对象
            PrivateKey privateKey = RSAUtil.string2PrivateKey(privateKeyStr);
            //加密后的内容Base64解码
            byte[] base642Byte = RSAUtil.base642Byte(byte2Base64);
            //用私钥解密
            byte[] privateDecrypt = RSAUtil.privateDecrypt(base642Byte, privateKey);
            //解密后的明文
            System.out.println("解密后的明文: " + new String(privateDecrypt));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
测试结果如下： 


RSA公钥Base64编码:MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA20p3Q88SmVUPpA+r/0hWY/LbMCsllwXK
UrXY13pG26BKsgtMm6IAGr6psS8cQ+AU75RpH3lTtt81wIfCHm9+vo4kVt66y8G0kfYSJ9Qlw2oH
5lwab8knPPb+NQNwE7WvceRczKh4XIEfNcgXZyKrcDUIpIsP6rNbZ70JYRhYiagqyLsb39ib4eO6
Zf6nmnrl3NPGeW4qFoivNudAld5E04gt2vCEEpuVt3x1/W3lVzD2gzz9rfkzjFvWwfGYjHMcZZNH
Z1h1G60ssSHh7WKV8f6EglPRQssimUKXX4De6g5SVABPs6MEOj0RYYyunJ8unA448u7/TCcMjV/b
vnndDwIDAQAB
RSA私钥Base64编码:MIIEvQIBADANBgkqhkiG9w0BAQEFAASCBKcwggSjAgEAAoIBAQDbSndDzxKZVQ+kD6v/SFZj8tsw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公钥加密并Base64编码的结果：rbHqJI9jlPLj/n4VP7d4jJRG1WDsDoWYib4BGjXEep6ym9FLiuCKCEwTDPuvvRzlH2BVFjkA0nN+
cjDo/u4PPofxK0a8Ipz0xYvnnQc9q+k8r0QD1uTx8PmnZLEv4rjwfIra/ho8VpYkPA7F1KkwDTyI
RIL06hngkhCi1aDym5oIP4vv+kxvi1uArVU04afXo6K4MTtzAesbG8f/qLHV7ywcBVNvb0QnuLNX
7jAWtfHfEGQibuA1EKbh35RcTjKlSW6vHTmg/f3fdHAfwKM/eh9LdMUjpsmfUoFfm8Ep7avjXbn+
12aXhtVZy8EYLIf1ZckefM95F808XN4HIsth6A==
解密后的明文: hello, i am infi, good night!