RSA 加密算法封装工具类

package com.hejjon.encryptdemo;

import javax.crypto.Cipher;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;

/**
 *  封装RSA加密工具类
 * @author: cs
 * @date: 2023-02-16 13:34:36
 * @since: 1.0
 */
public class RSAUtil {

    private static final String RSA = "RSA";

    private static String rsaPublicKey = null;
    private static String rsaPrivateKey = null;

    /**
     * //构建密钥对，保存公私钥
     *
     * @throws NoSuchAlgorithmException
     */
    static {
        try {
            KeyPairGenerator rsa = KeyPairGenerator.getInstance(RSA);
            rsa.initialize(512);
            KeyPair keyPair = rsa.generateKeyPair();
            // 生成公钥
            RSAPublicKey rsaPublic = (RSAPublicKey) keyPair.getPublic();
            // 生成私钥
            RSAPrivateKey rsaPrivate = (RSAPrivateKey) keyPair.getPrivate();

            // 生成公钥字符串
            rsaPublicKey = Base64.getEncoder().encodeToString(rsaPublic.getEncoded());
            // 生成私钥字符串
            rsaPrivateKey = Base64.getEncoder().encodeToString(rsaPrivate.getEncoded());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 私钥加密
     * @return
     * @throws Exception
     */
    public static String encByPrivateKey(String content) throws Exception {
        if (content == null || "".equals(content)) {
            throw new Exception("content is null or empty!");
        }
        System.out.println("要加密的数据: " + content);
        // 在构建密钥对时对秘钥进行了base64 编码, 这里需要先解码
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(Base64.getDecoder().decode(rsaPrivateKey));
        KeyFactory keyFactory = KeyFactory.getInstance(RSA);
        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
        // 创建Cipher对象
        Cipher cipher = Cipher.getInstance(RSA);
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
        // 加密
        byte[] bytes = cipher.doFinal(content.getBytes());
        String result = Base64.getEncoder().encodeToString(bytes);
         System.out.println("私钥加密的结果: " + result);
        return result;
    }

    /**
     * 公钥解密
     *
     * @param
     * @param result       加密的数据
     * @return
     */
    public static String decByPublicKey(String result) throws Exception {
        // 先对公钥进行Base64 解码
        X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(Base64.getDecoder().decode(rsaPublicKey));
        KeyFactory keyFactory = KeyFactory.getInstance(RSA);
        PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
        // 创建Cipher对象
        Cipher cipher = Cipher.getInstance(RSA);
        cipher.init(Cipher.DECRYPT_MODE, publicKey);
        byte[] bytes = cipher.doFinal(Base64.getDecoder().decode(result));
        String content = new String(bytes);
        System.out.println("公钥解密的结果: " + content);
        return content;
    }
    
}