RSA加密解密-java

RSA加密解密

maven依赖：

 
   
       org.apache.axis
       axis
       1.4
   
   
   
       commons-codec
       commons-codec
       1.10
   

RSAUtil工具类代码：

package common;

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

import javax.crypto.Cipher;
import java.io.BufferedWriter;
import java.io.ByteArrayOutputStream;
import java.io.FileWriter;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

/**
 * @program: Demo
 * @Date: 2019/2/21 22:56
 * @Author: LiJc
 * @Description:
 */
public class RSAUtil {
    /**
     * 转密钥字符串（base64编码）
     *
     * @return
     */
    public static String getKeyString(Key key) throws Exception {
        byte[] keyBytes = key.getEncoded();
        String s = new String(Base64.encodeBase64(keyBytes));
        return s;
    }

    /**
     * 得到公钥
     * @param publicKey 密钥字符串（经过base64编码）
     * @throws Exception
     */
    public static RSAPublicKey getPublicKey(String publicKey) throws NoSuchAlgorithmException, InvalidKeySpecException {
        //通过X509编码的Key指令获得公钥对象
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(Base64.decodeBase64(publicKey));
        RSAPublicKey key = (RSAPublicKey) keyFactory.generatePublic(x509KeySpec);
        return key;
    }

    /**
     * 得到私钥
     * @param privateKey 密钥字符串（经过base64编码）
     * @throws Exception
     */
    public static RSAPrivateKey getPrivateKey(String privateKey) throws NoSuchAlgorithmException, InvalidKeySpecException {
        //通过PKCS#8编码的Key指令获得私钥对象
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKey));
        RSAPrivateKey key = (RSAPrivateKey) keyFactory.generatePrivate(pkcs8KeySpec);
        return key;
    }

    /**
     * 生成密钥对
     * @param pubfilePath 公钥存放的文件路径
     * @param prifilePath 私钥存放的文件路径
     */
    public static void genKeyPair(String pubfilePath, String prifilePath) {
        // KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
        KeyPairGenerator keyPairGen = null;
        try {
            keyPairGen = KeyPairGenerator.getInstance("RSA");
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        // 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();
        // 得到私钥
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        // 得到公钥
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        try {
            // 得到公钥字符串
            String publicKeyString = getKeyString(publicKey);
            // 得到私钥字符串
            String privateKeyString = getKeyString(privateKey);
            // 将密钥对写入到文件
            FileWriter pubfw = new FileWriter(pubfilePath);
            FileWriter prifw = new FileWriter(prifilePath);
            BufferedWriter pubbw = new BufferedWriter(pubfw);
            BufferedWriter pribw = new BufferedWriter(prifw);
            pubbw.write(publicKeyString);
            pribw.write(privateKeyString);
            pubbw.flush();
            pubbw.close();
            pubfw.close();
            pribw.flush();
            pribw.close();
            prifw.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 公钥加密
     * @param data		需要加密的内容
     * @param publicKey	公钥
     * @return
     */
    public static String publicEncrypt(String data, RSAPublicKey publicKey){
        try{
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            return new String(Base64.encodeBase64(rsaSplitCodec(cipher, Cipher.ENCRYPT_MODE, data.getBytes("UTF-8"), publicKey.getModulus().bitLength())));
        }catch(Exception e){
            throw new RuntimeException("加密字符串[" + data + "]时遇到异常", e);
        }
    }

    /**
     * 私钥解密
     * @param data			需要加密的内容
     * @param privateKey	私钥
     * @return
     */

    public static String privateDecrypt(String data, RSAPrivateKey privateKey){
        try{
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            return new String(rsaSplitCodec(cipher, Cipher.DECRYPT_MODE, Base64.decodeBase64(data), privateKey.getModulus().bitLength()), "UTF-8");
        }catch(Exception e){
            throw new RuntimeException("解密字符串[" + data + "]时遇到异常", e);
        }
    }

    private static byte[] rsaSplitCodec(Cipher cipher, int opmode, byte[] datas, int keySize){
        int maxBlock = 0;
        if(opmode == Cipher.DECRYPT_MODE){
            maxBlock = keySize / 8;
        }else{
            maxBlock = keySize / 8 - 11;
        }
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] buff;
        int i = 0;
        try{
            while(datas.length > offSet){
                if(datas.length-offSet > maxBlock){
                    buff = cipher.doFinal(datas, offSet, maxBlock);
                }else{
                    buff = cipher.doFinal(datas, offSet, datas.length-offSet);
                }
                out.write(buff, 0, buff.length);
                i++;
                offSet = i * maxBlock;
            }
        }catch(Exception e){
            throw new RuntimeException("加解密阀值为["+maxBlock+"]的数据时发生异常", e);
        }
        byte[] resultDatas = out.toByteArray();
        IOUtils.closeQuietly(out);
        return resultDatas;
    }
}

单元测试：
1.先生成密钥对test1()方法。
2.从密钥的txt文件中读取密钥内容进行加解密。

package common;

import org.junit.Test;

import java.security.NoSuchAlgorithmException;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;

/**
 * @program: Demo
 * @Date: 2019/2/21 23:07
 * @Author: LiJc
 * @Description:
 */
public class RSATest {

    /**
     * 生成密钥对
     */
    @Test
    public void test1(){
        RSAUtil.genKeyPair("D:\\公钥.txt","D:\\私钥.txt");
    }

    @Test
    public void test2() throws InvalidKeySpecException, NoSuchAlgorithmException {
        String content = "真香警告！";
        System.out.println("原始内容为："+content);
        String pubkey = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCQ1IqhPNo8M/R1pHpocNuJ6enntJoB7OAaJrVoaHbvJOI4APkheX0J1UKizOGQNRr/V6vp3B+3MrPVGJ4lfRirrgnIK86PD5K/MChSWhxslWf3jQxr7AO8rMIPre7uoGjmY3pbSY82QUGDEhgDVsWTLTjWWqFQHVTwEfBPGgaktQIDAQAB";
        //根据公钥key获取公钥
        RSAPublicKey publicKey =  RSAUtil.getPublicKey(pubkey);
        //加密
        String content1 = RSAUtil.publicEncrypt(content, publicKey);
        System.out.println("加密后内容为："+content1);
        String prikey = "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";
        //获取私钥
        RSAPrivateKey privateKey = RSAUtil.getPrivateKey(prikey);
        //解密
        String content2 = RSAUtil.privateDecrypt(content1, privateKey);
        System.out.println("解密后内容为："+content2);
    }
}

调用test1()生成密钥对 (注意：每次生成的都是不一样的，代码中的密钥对为我此次测试生成的密钥对)
得到如下文件：

调用test2()的测试结果：