rsa加解密

Posted 2020-12-14 3xiaoleilei

package com.rsa;

 

import java.security.KeyFactory;

import java.security.KeyPair;

import java.security.KeyPairGenerator;

import java.security.NoSuchAlgorithmException;

import java.security.SecureRandom;

import java.security.interfaces.RSAPrivateKey;

import java.security.interfaces.RSAPublicKey;

import java.security.spec.PKCS8EncodedKeySpec;

import java.security.spec.X509EncodedKeySpec;

import java.util.HashMap;

import java.util.Map;

 

import javax.crypto.Cipher;

 

import org.apache.commons.codec.binary.Base64;

 

public class Test {

 

    private static Map<Integer, String> keyMap = new HashMap<Integer, String>();

 

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

        // TODO Auto-generated method stub

 

        // 用于封装随机产生的公钥与私钥

        { // 生成公钥和私钥

            genKeyPair();

            // 加密字符串

            String message = "df723820";

            System.out.println("随机生成的公钥为:" + keyMap.get(0));

            System.out.println("随机生成的私钥为:" + keyMap.get(1));

            String messageEn = encrypt(message, keyMap.get(0));

            System.out.println(message + " 加密后的字符串为:" + messageEn);

            String messageDe = decrypt(messageEn, keyMap.get(1));

            System.out.println("还原后的字符串为:" + messageDe);

        }

    }

 

    public static void genKeyPair() throws NoSuchAlgorithmException { // KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象

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

        // 初始化密钥对生成器，密钥大小为96-1024位

        keyPairGen.initialize(1024, new SecureRandom());

        // 生成一个密钥对，保存在keyPair中

        KeyPair keyPair = keyPairGen.generateKeyPair();

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

        // 得到私钥

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

        // 得到公钥

        String publicKeyString = new String(Base64.encodeBase64(publicKey.getEncoded()));

        // 得到私钥字符串

        String privateKeyString = new String(Base64.encodeBase64((privateKey.getEncoded())));

        // 将公钥和私钥保存到

        keyMap.put(0, publicKeyString);

        // 0表示公钥

        keyMap.put(1, privateKeyString);

        // 1表示私钥

    }

 

    public static String encrypt(String str, String publicKey) throws Exception {

        // base64编码的公钥

        byte[] decoded = Base64.decodeBase64(publicKey);

        RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA")

                .generatePublic(new X509EncodedKeySpec(decoded));

        // RSA加密

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

        cipher.init(Cipher.ENCRYPT_MODE, pubKey);

        String outStr = Base64.encodeBase64String(cipher.doFinal(str.getBytes("UTF-8")));

        return outStr;

    }

 

    public static String decrypt(String str, String privateKey) throws Exception {

        // 64位解码加密后的字符串

        byte[] inputByte = Base64.decodeBase64(str.getBytes("UTF-8"));

        // base64编码的私钥

        byte[] decoded = Base64.decodeBase64(privateKey);

        RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA")

                .generatePrivate(new PKCS8EncodedKeySpec(decoded));

        // RSA解密

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

        cipher.init(Cipher.DECRYPT_MODE, priKey);

        String outStr = new String(cipher.doFinal(inputByte));

        return outStr;

    }

 

}