Java实现RSA加密解密

RSA加密解密分享，感谢大神!!
参考资料：https://www.cnblogs.com/leeego-123/p/10450339.html

maven的POM文件内容：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>cn.diaoyc</groupId>
    <artifactId>EncryptUtil</artifactId>
    <version>2.0-SNAPSHOT</version>
    <dependencies>
        <dependency>
            <groupId>org.bouncycastle</groupId>
            <artifactId>bcprov-jdk16</artifactId>
            <version>1.46</version>
        </dependency>
        <dependency>
            <groupId>commons-codec</groupId>
            <artifactId>commons-codec</artifactId>
            <version>1.9</version>
        </dependency>
        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.4</version>
        </dependency>

    </dependencies>

</project>

这是java代码开箱即用，很香

package cn.diaoyc.encryptUtil;

import org.apache.commons.codec.binary.Base64;
import org.apache.commons.io.IOUtils;
import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
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;
import java.util.HashMap;
import java.util.Map;

/**
 * @author Tony     
 * @projectName AESCB
 * @title RSAUtils   
 * @package cn.diaoyc.encryptUtil   
 * @date 2020/5/11 -- 20:52
 *  
 */

/**
 * RSA加密解密
 * createKeys() 此方法用于生成密钥对
 * getPublicKey() 此方法用于得到经过编码的公钥
 * getPrivateKey() 此方法用于得到经过编码的私钥
 * publicEncrypt() 此方法用于公钥加密
 * privateDecrypt() 此方法用于私钥解密
 * privateEncrypt() 此方法用于私钥加密
 * publicDecrypt()  此方法用于公钥解密
 * 使用方法：
 * 1.调用createKeys() 生成Map类型的密钥对
 * 2.如果是使用公钥加密私钥解密模式：
 *      2.1 公钥加密：调用publicEncrypt() 进行加密 返回加密的字符串，需要传入明文数据、通过getPublicKey()方法获取经过编码的公钥
 *      2.2 私钥解密：调用privateDecrypt() 进行解密，返回解密的字符串，需要传入加密过的密文，通过getPrivateKey()方法获取经过编码的私钥
 * 3.如果是使用私钥钥加密公钥解密模式：
 *      可参考上一个点的使用方法
 *
 * 注意使用是需要将异常抛出
 *
 * 感谢大神！！！！！
 * 参考资料：https://www.cnblogs.com/leeego-123/p/10450339.html
 */
public class RSAUtils {
    //    设置编码格式
    public static final String CHARSET = "UTF-8";
    //    指定加密方式
    public static final String RSA_ALGORITHM = "RSA";

    /**
     * 获取密钥对
     * @param keySize 密钥长度
     * @return 返回装有密钥对的Map
     */
    public static Map<String, String> createKeys(int keySize){
        //为RSA算法创建一个KeyPairGenerator对象
        KeyPairGenerator kpg;
        try {
            kpg = KeyPairGenerator.getInstance(RSA_ALGORITHM);
        }catch (NoSuchAlgorithmException e){
            throw new IllegalArgumentException("No such algorithm-->[" + RSA_ALGORITHM + "]");
        }
        // 初始化KeyPairGenerator，密钥长度
        kpg.initialize(keySize);
        //生成密钥对
        KeyPair keyPair = kpg.generateKeyPair();
        //得到公钥
        Key publicKey = keyPair.getPublic();
        String publicKeyStr = Base64.encodeBase64URLSafeString(publicKey.getEncoded());
        //得到私钥
        PrivateKey privateKey = keyPair.getPrivate();
        String privateKeyStr = Base64.encodeBase64URLSafeString(privateKey.getEncoded());
        //将密钥放入MAP返回
        Map<String, String> ketPairMap = new HashMap<String, String>();
        ketPairMap.put("publicKey",publicKeyStr);
        ketPairMap.put("privateKey",privateKeyStr);
        return ketPairMap;
    }

    /**
     * 得到公钥
     * @param publicKey 经过64位编码的密钥字符串
     * @return 返回公钥
     * @throws NoSuchAlgorithmException
     * @throws InvalidKeySpecException
     */
    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_ALGORITHM);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(Base64.decodeBase64(publicKey));
        RSAPublicKey key = (RSAPublicKey) keyFactory.generatePublic(x509KeySpec);
        return key;
    }

    /**
     * 得到私钥
     * @param privateKey  经过64位编码的密钥字符串
     * @return 返回私钥
     * @throws NoSuchAlgorithmException
     * @throws InvalidKeySpecException
     */
    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_ALGORITHM);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKey));
        RSAPrivateKey key = (RSAPrivateKey) keyFactory.generatePrivate(pkcs8KeySpec);
        return key;
    }
    /**
     * 公钥加密
     * @param data 需要加密的内容
     * @param publicKey 公钥
     * @return 返回加密内容
     */
    public static String publicEncrypt(String data, RSAPublicKey publicKey){
        try{
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            return Base64.encodeBase64URLSafeString(rsaSplitCodec(cipher, Cipher.ENCRYPT_MODE, data.getBytes(CHARSET), 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 需要解密的内容
     * @param privateKey 私钥
     * @return 返回解密内容
     */

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

    /**
     * 私钥加密
     * @param data 需要加密的内容
     * @param privateKey 私钥
     * @return 返回加密内容
     */

    public static String privateEncrypt(String data, RSAPrivateKey privateKey){
        try{
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.ENCRYPT_MODE, privateKey);
            return Base64.encodeBase64URLSafeString(rsaSplitCodec(cipher, Cipher.ENCRYPT_MODE, data.getBytes(CHARSET), privateKey.getModulus().bitLength()));
        }catch(Exception e){
            throw new RuntimeException("加密字符串[" + data + "]时遇到异常", e);
        }
    }

    /**
     * 公钥解密
     * @param data 需要解密的内容
     * @param publicKey 公钥
     * @return 返回解密内容
     */

    public static String publicDecrypt(String data, RSAPublicKey publicKey){
        try{
            Cipher cipher = Cipher.getInstance(RSA_ALGORITHM);
            cipher.init(Cipher.DECRYPT_MODE, publicKey);
            return new String(rsaSplitCodec(cipher, Cipher.DECRYPT_MODE, Base64.decodeBase64(data), publicKey.getModulus().bitLength()), CHARSET);
        }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;
    }


}

最后来测试一下：

package cn.diaoyc.encryptUtil;

import java.util.Map;

/**
 * @author Tony     
 * @projectName AESCB
 * @title TestRSA   
 * @package cn.diaoyc.encryptUtil   
 * @date 2020/5/11 -- 22:41
 *  
 */
public class TestRSA {
    public static void main(String[] args) {
        Map<String, String> keyMap = RSAUtils.createKeys(1024);
        String  publicKey = keyMap.get("publicKey");
        String  privateKey = keyMap.get("privateKey");
        System.out.println("公钥: \n\r" + publicKey);
        System.out.println("私钥： \n\r" + privateKey);

        System.out.println("************这是公钥加密——私钥解密的方式-------------------");
        String str = "站在大明门前守卫的禁卫军，事先没有接到\n" +
                "有关的命令，但看到大批盛装的官员来临，也就\n" +
                "以为确系举行大典，因而未加询问。进大明门即\n" +
                "为皇城。文武百官看到端门午门之前气氛平静，\n" +
                "城楼上下也无朝会的迹象，既无几案，站队点名\n" +
                "的御史和御前侍卫“大汉将军”也不见踪影，不免\n" +
                "心中揣测，互相询问：所谓午朝是否讹传？";
        System.out.println("\r明文：\r\n" + str);
        System.out.println("\r明文大小：\r\n" + str.getBytes().length);
        try {
            //公钥加密
            String encodedData = RSAUtils.publicEncrypt(str, RSAUtils.getPublicKey(publicKey));

            System.out.println("密文：\r\n" + encodedData);
            //私钥解密
            String decodedData = RSAUtils.privateDecrypt(encodedData, RSAUtils.getPrivateKey(privateKey));

            System.out.println("解密后文字: \r\n" + decodedData);
        }catch (Exception e){
            throw new RuntimeException(e);
        }


    }
}