package com.panzhihua.common.utlis;

import org.apache.commons.codec.binary.Base64;
import org.jsoup.internal.StringUtil;

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.Arrays;
import java.util.HashMap;
import java.util.Map;


public class RSAUtils {

	private static Map<Integer, String> keyMap = new HashMap<Integer, String>(); // 用于封装随机产生的公钥与私钥

	
	/**
	 * 随机生成密钥对
	 * 
	 * @throws NoSuchAlgorithmException
	 */
	public static void genKeyPair() throws NoSuchAlgorithmException {
		// KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
		KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
		// 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();
		RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate(); // 得到私钥
		RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic(); // 得到公钥
		String publicKeyString = new String(Base64.encodeBase64(publicKey.getEncoded()));
		// 得到私钥字符串
		String privateKeyString = new String(Base64.encodeBase64((privateKey.getEncoded())));
		// 将公钥和私钥保存到Map
		System.out.println("publicKeyString:" + publicKeyString);
		System.out.println("privateKeyString:" + privateKeyString);
		keyMap.put(0, publicKeyString); // 0表示公钥
		keyMap.put(1, privateKeyString); // 1表示私钥
	}

	/**
	 * RSA公钥加密
	 *
	 * @param str       加密字符串
	 * @param publicKey 公钥
	 * @return 密文
	 * @throws Exception 加密过程中的异常信息
	 */
	public static String encrypt(String str, String publicKey) throws Exception {
		if (StringUtil.isBlank(str)) {
			return "";
		}
		// base64编码的公钥
		byte[] decoded = Base64.decodeBase64(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 = Base64.encodeBase64String(cipher.doFinal(str.getBytes("UTF-8")));
		return outStr;
	}

	/**
	 * RSA私钥解密
	 *
	 * @param str        加密字符串
	 * @param privateKey 私钥
	 * @return 铭文
	 * @throws Exception 解密过程中的异常信息
	 */
	public static String decrypt(String str, String privateKey) throws Exception {
		// 64位解码加密后的字符串
		byte[] inputByte = Base64.decodeBase64(str.getBytes("UTF-8"));
		// base64编码的私钥
		byte[] decoded = Base64.decodeBase64(privateKey);
		RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA")
				.generatePrivate(new PKCS8EncodedKeySpec(decoded));
		// RSA解密
		Cipher cipher = Cipher.getInstance("RSA");
		cipher.init(Cipher.DECRYPT_MODE, priKey);
		String outStr = new String(cipher.doFinal(inputByte));
		return outStr;
	}

	/**
	 * RSA私钥解密
	 *
	 * @param str        加密字符串
	 * @param privateKey 私钥
	 * @return 铭文
	 * @throws Exception 解密过程中的异常信息
	 */
	public static String decrypt2(String str, String privateKey) throws Exception {
		str = str.replace(" ", "+");
		// 64位解码加密后的字符串
		byte[] inputByte = Base64.decodeBase64(str.getBytes("UTF-8"));
		// base64编码的私钥
		byte[] decoded = Base64.decodeBase64(privateKey);
		RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA")
				.generatePrivate(new PKCS8EncodedKeySpec(decoded));
		// RSA解密
		Cipher cipher = Cipher.getInstance("RSA");
		cipher.init(Cipher.DECRYPT_MODE, priKey);
		String outStr = new String(cipher.doFinal(inputByte));
		return outStr;
	}

	public static String rsaEncrypt(String input, String rsaPublicKey) {
		String result = "";
		try {
			// 将Base64编码后的公钥转换成PublicKey对象
			byte[] buffer = Base64.decodeBase64(rsaPublicKey);
			KeyFactory keyFactory = KeyFactory.getInstance("RSA");
			X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
			PublicKey publicKey = keyFactory.generatePublic(keySpec);
			// 加密
			Cipher cipher = Cipher.getInstance("RSA");
			cipher.init(Cipher.ENCRYPT_MODE, publicKey);// ubli
			byte[] inputArray = input.getBytes();
			int inputLength = inputArray.length;
			// System.out.println("加密字节数：" + inputLength);
			// 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);
			}
			result = Base64.encodeBase64String(resultBytes);
		} catch (Exception e) {
			System.out.println("rsaEncrypt error:" + e.getMessage());
		}
		// System.out.println("加密的结果：" + result);
		return result;
	}

}