RSA加密算法-Java实现

最新推荐文章于 2025-07-16 09:45:08 发布

kj619899271

最新推荐文章于 2025-07-16 09:45:08 发布

阅读量1.5w

点赞数

CC 4.0 BY-SA版权

文章标签：加密算法 string exception byte import

本文链接：https://blog.youkuaiyun.com/kj619899271/article/details/6221187

本文介绍了一种使用Java实现RSA非对称加密算法的方法，包括生成公钥和私钥、利用公钥加密数据及通过私钥解密的过程。示例代码展示了如何存储和读取密钥，以及具体的加密解密步骤。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

package test;
import java.io.*;
import java.security.*;

import javax.crypto.*;
import javax.crypto.spec.*;
import java.security.spec.X509EncodedKeySpec;
import java.security.spec.PKCS8EncodedKeySpec;
import sun.misc.*;

/**
* Title: RSA非对称型加密的公钥和私钥
* Description: 
* Copyright: Copyright (c) 2003
* Company: 
* @author not attributable
* @version 1.0
*/

public class RSAUtil {
private KeyPairGenerator kpg = null;
private KeyPair kp = null;
private PublicKey public_key = null;
private PrivateKey private_key = null;

/**
   * 构造函数
   * @param in 指定密匙长度（取值范围：512～2048）
   * @throws NoSuchAlgorithmException 异常
   */
public RSAUtils(int in, String address) throws NoSuchAlgorithmException,
      FileNotFoundException, IOException
      {
            kpg = KeyPairGenerator.getInstance("RSA"); //创建‘密匙对’生成器
            kpg.initialize(in); //指定密匙长度（取值范围：512～2048）
            kp = kpg.genKeyPair(); //生成‘密匙对’，其中包含着一个公匙和一个私匙的信息
            public_key = kp.getPublic(); //获得公匙
            private_key = kp.getPrivate(); //获得私匙

            sun.misc.BASE64Encoder b64 = new sun.misc.BASE64Encoder();
            String pkStr = b64.encode(public_key.getEncoded());
            String prStr = b64.encode(private_key.getEncoded());
            System.out.print("pkStr length:" +pkStr.length() +pkStr);

            FileWriter fw=new FileWriter(address + "/private_key.dat");
            fw.write(prStr);
            fw.close();

            FileWriter fw2 = new FileWriter(address + "/public_key.dat");
            fw2.write(pkStr);
            fw2.close();
     }

   /**
    *加密的方法
    */
   private static String encrypt(String source) throws Exception{

    /** 将文件中的公钥对象读出 */
   FileReader fr = new FileReader("c://public_key.dat");
   BufferedReader br=new BufferedReader(fr);//建立BufferedReader对象，并实例化为br
   String getPbKey = "";
      while(true){
     String aLine = br.readLine();
       if(aLine==null)break;
       getPbKey += aLine;
   }
      System.out.println( "myBuilderStr : length: " + getPbKey.length() +"

"+getPbKey );
       BASE64Decoder   b64d = new BASE64Decoder();
      byte [] keyByte = b64d.decodeBuffer(getPbKey);
      X509EncodedKeySpec x509ek = new X509EncodedKeySpec(keyByte);
      KeyFactory keyFactory = KeyFactory.getInstance("RSA");
      PublicKey publicKey = keyFactory.generatePublic(x509ek);

      Cipher cipher = Cipher.getInstance("RSA");
      cipher.init(Cipher.ENCRYPT_MODE,publicKey);
     byte[] sbt = source.getBytes();
     byte [] epByte = cipher.doFinal(sbt);
     BASE64Encoder encoder = new BASE64Encoder();
     String epStr = encoder.encode(epByte);
     return epStr;

}

   /**
    *解密的方法
    */
   public static String decrypt(String cryptograph) throws Exception{

    FileReader fr = new FileReader("c://private_key.dat");
    BufferedReader br=new BufferedReader(fr);//建立BufferedReader对象，并实例化为

br
    String getPvKey = "";
       while(true){
      String aLine = br.readLine();
        if(aLine==null)break;
        getPvKey += aLine;
    }
       BASE64Decoder   b64d = new BASE64Decoder();
        byte [] keyByte = b64d.decodeBuffer(getPvKey);
        PKCS8EncodedKeySpec s8ek = new PKCS8EncodedKeySpec(keyByte);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey privateKey = keyFactory.generatePrivate(s8ek);


    /** 得到Cipher对象对已用公钥加密的数据进行RSA解密 */
    Cipher cipher = Cipher.getInstance("RSA");
    cipher.init(Cipher.DECRYPT_MODE, privateKey);
    BASE64Decoder decoder = new BASE64Decoder();
    byte[] b1 = decoder.decodeBuffer(cryptograph);
    /** 执行解密操作 */
    byte[] b = cipher.doFinal(b1);
    return new String(b);
}

public static void main(String[] args) {
    try {
      new KeyRSA(1024, "D:/");      //私匙和公匙保存到D盘下的文件中.
        System.out.println("");
        String getEptStr = encrypt("fengyupeng");
        System.out.println("getEptStr:"+getEptStr);
        String drpStr = decrypt(getEptStr);
        System.out.println("drpStr:"+drpStr);
    }
    catch (IOException ex) {
ex.printStackTrace();
    }
    catch (NoSuchAlgorithmException ex) {
ex.printStackTrace();
    }catch(Exception ex){
ex.printStackTrace();
    }

}