package com.RNRSA;

import java.io.ByteArrayOutputStream;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

import javax.crypto.Cipher;


/**
 * 世联行 WorldUnion <br>
 * 项目名称：世联行:WorldUnionYZG <br>
 * 类注释：<br>
 * 作者：0210289 <br>
 * 创建时间：on 2018/11/16<br>
 * 邮箱：xiaofeng3@worldunion.com.cn<br>
 * 备注：<br>
 */
public class RSAEncrypt {
    /** */
    /**
     * 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 = "RSAPublicKey";

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

    /** */
    /**
     * 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;
    }

    /** */
    /**
     * <p>
     * 用私钥对信息生成数字签名
     * </p>
     *
     * @param data       已加密数据
     * @param privateKey 私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static String sign(byte[] data, String privateKey) throws Exception {
        byte[] keyBytes = Base64Utils.decode(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(privateK);
        signature.update(data);
        return Base64Utils.encode(signature.sign(),0);
    }

    /** */
    /**
     * <p>
     * 校验数字签名
     * </p>
     *
     * @param data      已加密数据
     * @param publicKey 公钥(BASE64编码)
     * @param sign      数字签名
     * @return
     * @throws Exception
     */
    public static boolean verify(byte[] data, String publicKey, String sign)
            throws Exception {
        byte[] keyBytes = Base64Utils.decode(publicKey);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PublicKey publicK = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(publicK);
        signature.update(data);
        return signature.verify(Base64Utils.decode(sign));
    }

    /** */
    /**
     * <P>
     * 私钥解密
     * </p>
     *
     * @param privateKey    私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static String  decryptByPrivateKey(String str, String privateKey){
        try {
            byte[] encryptedData = str.getBytes("UTF-8");
            byte[] keyBytes = Base64Utils.decode(privateKey);
            PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
            KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
            Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
//        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
            Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");

            cipher.init(Cipher.DECRYPT_MODE, privateK);
            int inputLen = encryptedData.length;
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int offSet = 0;
            byte[] cache;
            int i = 0;
            // 对数据分段解密
            while (inputLen - offSet > 0) {
                if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                    cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
                } else {
                    cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
                }
                out.write(cache, 0, cache.length);
                i++;
                offSet = i * MAX_DECRYPT_BLOCK;
            }
            byte[] decryptedData = out.toByteArray();
            out.close();
            return Base64Utils.encode(decryptedData,0);
        }catch (Exception e){
            e.printStackTrace();
        }
        return "";

    }

    /** */
    /**
     * <p>
     * 公钥解密
     * </p>
     *
     * @param publicKey 公钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static String decryptByPublicKey(String str, String publicKey){
        try {
            byte[] encryptedData = str.getBytes("UTF-8");
            byte[] keyBytes = Base64Utils.decode(publicKey);
            X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
            KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
            Key publicK = keyFactory.generatePublic(x509KeySpec);
//        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
            Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            cipher.init(Cipher.DECRYPT_MODE, publicK);
            int inputLen = encryptedData.length;
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int offSet = 0;
            byte[] cache;
            int i = 0;
            // 对数据分段解密
            while (inputLen - offSet > 0) {
                if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                    cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
                } else {
                    cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
                }
                out.write(cache, 0, cache.length);
                i++;
                offSet = i * MAX_DECRYPT_BLOCK;
            }
            byte[] decryptedData = out.toByteArray();
            out.close();
            return Base64Utils.encode(decryptedData,0);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "";

    }

    /** */
    /**
     * <p>
     * 公钥加密
     * </p>
     *
     * @param str       源数据
     * @param publicKey 公钥(BASE64编码)
     * @return
     */
    public static String encryptByPublicKey(String str, String publicKey) {
        try {
//            str = StringUtils.reverse(str);
            byte[] data = str.getBytes("UTF-8");
            byte[] keyBytes = Base64Utils.decode(publicKey);
            X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
            KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
            Key publicK = keyFactory.generatePublic(x509KeySpec);
            // 对数据加密
//            Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
            Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);
            cipher.init(Cipher.ENCRYPT_MODE, publicK);
            int inputLen = data.length;
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int offSet = 0;
            byte[] cache;
            int i = 0;
            // 对数据分段加密
            while (inputLen - offSet > 0) {
                if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                    cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
                } else {
                    cache = cipher.doFinal(data, offSet, inputLen - offSet);
                }
                out.write(cache, 0, cache.length);
                i++;
                offSet = i * MAX_ENCRYPT_BLOCK;
            }
            byte[] encryptedData = out.toByteArray();
            out.close();
            return ConvertUtils.bytes2HexString(encryptedData);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "";

    }

    /** */
    /**
     * <p>
     * 私钥加密
     * </p>
     *
     * @param str       源数据
     * @param privateKey 私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static String encryptByPrivateKey(String str, String privateKey)
    {
        try {
            byte[] data = str.getBytes("UTF-8");
            byte[] keyBytes = Base64Utils.decode(privateKey);
            PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
            KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
            Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
//        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
//                    Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
            Cipher cipher = Cipher.getInstance(KEY_ALGORITHM);
            cipher.init(Cipher.ENCRYPT_MODE, privateK);
            int inputLen = data.length;
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int offSet = 0;
            byte[] cache;
            int i = 0;
            // 对数据分段加密
            while (inputLen - offSet > 0) {
                if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                    cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
                } else {
                    cache = cipher.doFinal(data, offSet, inputLen - offSet);
                }
                out.write(cache, 0, cache.length);
                i++;
                offSet = i * MAX_ENCRYPT_BLOCK;
            }
            byte[] encryptedData = out.toByteArray();
            out.close();
            return ConvertUtils.bytes2HexString(encryptedData);
//                    return encryptedData;
        }catch (Exception e){
            e.printStackTrace();
        }
        return "";
    }

    /** */
    /**
     * <p>
     * 获取私钥
     * </p>
     *
     * @param keyMap 密钥对
     * @return
     * @throws Exception
     */
    public static String getPrivateKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PRIVATE_KEY);
        return Base64Utils.encode(key.getEncoded(),0);
    }

    /** */
    /**
     * <p>
     * 获取公钥
     * </p>
     *
     * @param keyMap 密钥对
     * @return
     * @throws Exception
     */
    public static String getPublicKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PUBLIC_KEY);
        return Base64Utils.encode(key.getEncoded(),0);
    }

}