# 前端

1. 引入 jsencrypt

	# 使用 npm 引入
	cnpm install jsencrypt

2. 创建通用的工具 JS

公钥可以通过此网站在线生成在线生成公钥私钥对
示例代码使用的密码格式：
密钥长度：1024 bit
密钥格式：PKCS#8

注意：当使用 IDE 将密钥转换成一行时，小心换行符，有的 IDE 不显示。此时可以将文本粘贴到 Chrome Console 检查！

	import { JSEncrypt } from 'jsencrypt'

	/**
	* 公钥是通过 base64 加密转化的
	* 默认的公钥，用于登录密码的加密.
	*/
	var publicKey = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQC4jFr2m2d0AWFhmHs23LcW6649tZUk+7vxPjHW+/YZeCgXi8x9ANK0BGt8Kji8Ujc+K+YU7oLU0AlMoXzG05/Ghc7GNfLBb0tv2hYMYFKzctYR8tHGv0Zxp1nV0AJYiZKqW+v9WTWvfFMs1MOshADkTk9qHDpsxUYMy8CU6j09MQIDAQAB"

	/**
	* RSA 加密封装
	* @param {需要加密的数据} data
	* @returns
	*/
	export function encrypt(data) {
	var jsEncrypt = new JSEncrypt();
	jsEncrypt.setPublicKey(publicKey);
	return jsEncrypt.encrypt(data);
	}

# Java

	package com.demo.utils;

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

	import javax.crypto.Cipher;
	import java.io.ByteArrayOutputStream;
	import java.security.KeyFactory;
	import java.security.PrivateKey;
	import java.security.spec.PKCS8EncodedKeySpec;

	/**
	* RSA 加密算法工具类
	*
	* @author utrix
	* @date 2021/11/16
	*/
	public final class RSAUtil {

	/**
	* RSA 最大解密密文大小
	*/
	private static final int MAX_DECRYPT_BLOCK = 128;

	/**
	* 获取私钥
	*
	* @param privateKey 私钥字符串
	* @return {@link PrivateKey}
	*/
	@SneakyThrows
	public static PrivateKey getPrivateKey(String privateKey) {
	KeyFactory keyFactory = KeyFactory.getInstance("RSA");
	byte[] decodedKey = Base64.decodeBase64(privateKey.getBytes());
	PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(decodedKey);
	return keyFactory.generatePrivate(keySpec);
	}

	/**
	* RSA 解密
	*
	* @param data 待解密数据
	* @param privateKey 私钥
	* @return {@link String} 解密好的字符串
	*/
	@SneakyThrows
	public static String decrypt(String data, PrivateKey privateKey) {
	Cipher cipher = Cipher.getInstance("RSA");
	cipher.init(Cipher.DECRYPT_MODE, privateKey);
	byte[] dataBytes = Base64.decodeBase64(data);
	int inputLen = dataBytes.length;

	int offset = 0;
	byte[] cache;
	int i = 0;

	try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {
	// 对数据分段解密
	while (inputLen - offset > 0) {
	if (inputLen - offset > MAX_DECRYPT_BLOCK) {
	cache = cipher.doFinal(dataBytes, offset, MAX_DECRYPT_BLOCK);
	} else {
	cache = cipher.doFinal(dataBytes, offset, inputLen - offset);
	}
	out.write(cache, 0, cache.length);
	i++;
	offset = i*MAX_DECRYPT_BLOCK;
	}
	// 解密后的内容
	return out.toString("UTF-8");
	}
	}

	private RSAUtil() {}
	}

# 测试

	package com.unionstone.fny.utils;

	import org.junit.jupiter.api.Test;
	import java.security.PrivateKey;

	class RSAUtilTest {

	// 与前端一块生成的公钥私钥对。此为私钥（此为示例值，已被和谐不可直接复用）
	private static final String PRIVATE_KEY = "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";

	@Test
	void decrypt() {
	// 前端加密的密钥
	String ciphertext = "xxxx";
	PrivateKey privateKey = RSAUtil.getPrivateKey(PRIVATE_KEY);
	String decrypt = RSAUtil.decrypt(ciphertext, privateKey);
	System.out.println(decrypt);
	}

	}