package com.zcloud.primeport.plan.mjDevice;

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.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

/**
 * RSA公钥/私钥/签名工具包
 * <p>
 * 字符串格式的密钥在未在特殊说明情况下都为BASE64编码格式<br/>
 * 由于非对称加密速度极其缓慢，一般文件不使用它来加密而是使用对称加密，<br/>
 * 非对称加密算法可以用来对对称加密的密钥加密，这样保证密钥的安全也就保证了数据的安全
 * </p>
 *
 */
public class RSAUtils {

    /** */
    /**
     * 加密算法RSA
     */
    public static final String KEY_ALGORITHM = "RSA";

    /** */
    /**
     * 签名算法
     */
    public static final String SIGNATURE_ALGORITHM = "MD5withRSA";

    /** */
    /**
     * 获取公钥的key
     */
    private static final String PUBLIC_KEY = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDUoHAavCikaZxjlDM6Km8cX+ye78F4oF39AcEfnE1p2Yn9pJ9WFxYZ4Vkh6F8SKMi7k4nYsKceqB1RwG996SvHQ5C3pM3nbXCP4K15ad6QhN4a7lzlbLhiJcyIKszvvK8ncUDw8mVQ0j/2mwxv05yH6LN9OKU6Hzm1ninpWeE+awIDAQAB\n";

    /** */
    /**
     * 获取私钥的key
     */
    private static final String PRIVATE_KEY = "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";

    /** */
    /**
     * RSA最大加密明文大小
     */
    private static final int MAX_ENCRYPT_BLOCK = 117;

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

    /** */
    /**
     * <p>
     * 生成密钥对(公钥和私钥)
     * </p>
     *
     * @return
     * @throws Exception
     */
    public static Map<String, Object> genKeyPair() throws Exception {
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
        keyPairGen.initialize(1024);
        KeyPair keyPair = keyPairGen.generateKeyPair();
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        Map<String, Object> keyMap = new HashMap<String, Object>(2);
        keyMap.put(PUBLIC_KEY, publicKey);
        keyMap.put(PRIVATE_KEY, privateKey);
        return keyMap;
    }



    /**
     * 基于原生RSA公钥加密
     * @param password 用户密码
     * @param publicKey 公钥
     * @return
     * @throws Exception
     */
    public static String encrypt(String password, String publicKey) throws Exception {
        //base64编码的公钥
        byte[] decoded = java.util.Base64.getDecoder().decode(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;
        byte[] inputArray = password.getBytes("UTF-8");
        int inputLength = inputArray.length;
        // 最大加密字节数，超出最大字节数需要分组加密
        int MAX_ENCRYPT_BLOCK = 117;
        // 标识
        int offSet = 0;
        byte[] resultBytes = {};
        byte[] cache = {};
        while (inputLength - offSet > 0) {
            if (inputLength - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(inputArray, offSet, MAX_ENCRYPT_BLOCK);
                offSet += MAX_ENCRYPT_BLOCK;
            } else {
                cache = cipher.doFinal(inputArray, offSet, inputLength - offSet);
                offSet = inputLength;
            }
            resultBytes = Arrays.copyOf(resultBytes, resultBytes.length + cache.length);
            System.arraycopy(cache, 0, resultBytes, resultBytes.length - cache.length, cache.length);
        }
        outStr = java.util.Base64.getEncoder().encodeToString(resultBytes);
        return outStr;
    }

}
