package com.sdyc.datahub.api.utils;

/**
 * <pre>
 *
 * Created by zhenqin.
 * User: zhenqin
 * Date: 17/1/10
 * Time: 14:41
 * Vendor: NowledgeData
 * To change this template use File | Settings | File Templates.
 *
 * </pre>
 *
 * @author zhenqin
 */


import org.apache.commons.codec.binary.Base64;
import org.apache.commons.io.IOUtils;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.openssl.PEMReader;

import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileReader;
import java.nio.ByteBuffer;
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.HashMap;
import java.util.Map;

/**
 * <p>
 * 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
     */
    public static final String PUBLIC_KEY = "LocatorPublicKey";

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

    /**
     * RSA最大加密明文大小
     */
    public static final int MAX_ENCRYPT_BLOCK = 1024;

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


    static {
        Security.addProvider(new BouncyCastleProvider());
    }



    static class CipherXX {
        final Cipher decryptCipher;
        final Cipher encryptCihper;

        CipherXX(Key key) {
            try {
                KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
                if(key instanceof PublicKey) {
                    X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(key.getEncoded());
                    Key publicK = keyFactory.generatePublic(x509KeySpec);
                    decryptCipher = Cipher.getInstance(keyFactory.getAlgorithm());
                    decryptCipher.init(Cipher.DECRYPT_MODE, publicK);

                    // 对数据加密
                    encryptCihper = Cipher.getInstance(keyFactory.getAlgorithm());
                    encryptCihper.init(Cipher.ENCRYPT_MODE, publicK);
                } else {
                    PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(key.getEncoded());
                    Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);

                    decryptCipher = Cipher.getInstance(keyFactory.getAlgorithm());
                    decryptCipher.init(Cipher.DECRYPT_MODE, privateK);

                    encryptCihper = Cipher.getInstance(keyFactory.getAlgorithm());
                    encryptCihper.init(Cipher.ENCRYPT_MODE, privateK);
                }
            } catch (Exception e) {
                throw new IllegalStateException(e);
            }
        }


        public Cipher getDecryptCipher() {
            return decryptCipher;
        }

        public Cipher getEncryptCihper() {
            return encryptCihper;
        }
    }


    /**
     * Thread Local
     */
    protected final static ThreadLocal<Map> THREAD_LOCAL = new ThreadLocal<Map>();


    private RSAUtils() {

    }



    private static Cipher getCipher(Key key, int mode) throws Exception {
        Map<Key, CipherXX> KEY_CIPHER_MAP = THREAD_LOCAL.get();
        boolean put = false;
        if(KEY_CIPHER_MAP == null) {
            KEY_CIPHER_MAP = new HashMap<Key, CipherXX>(3);
            put = true;
        }

        CipherXX cipher = KEY_CIPHER_MAP.get(key);
        if(cipher == null) {
            cipher = new CipherXX(key);
            KEY_CIPHER_MAP.put(key, cipher);
        }

        if(put) THREAD_LOCAL.set(KEY_CIPHER_MAP);
        return mode == Cipher.ENCRYPT_MODE ? cipher.getEncryptCihper() : cipher.getDecryptCipher();
    }



    /**
     * <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();
        PublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        PrivateKey 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>
     * 生成密钥对(公钥和私钥)
     * </p>
     *
     * @return
     * @throws Exception
     */
    public static Map<String, Object> genFileKeyPair(File privateKeyFile) throws Exception {
        PEMReader reader = null;
        try {
            reader = new PEMReader(new FileReader(privateKeyFile), null);
            KeyPair keyPair = (KeyPair) reader.readObject();

            PublicKey publicKey = keyPair.getPublic();
            PrivateKey privateKey = keyPair.getPrivate();

            Map<String, Object> keyMap = new HashMap<String, Object>(2);
            keyMap.put(PUBLIC_KEY, publicKey);
            keyMap.put(PRIVATE_KEY, privateKey);
            return keyMap;
        } finally {
            IOUtils.closeQuietly(reader);
        }
    }



    /**
     * <p>
     * 生成密钥对(公钥和私钥)
     * </p>
     *
     * @return
     * @throws Exception
     */
    public static PublicKey genPublicKey(File publicKeyFile) throws Exception {
        PEMReader reader =  null;
        try {
            reader =  new PEMReader(new FileReader(publicKeyFile), null);
            return  (PublicKey) reader.readObject();
        } finally {
            IOUtils.closeQuietly(reader);
        }
    }




    /**
     * <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, PrivateKey privateKey) throws Exception {
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(privateKey.getEncoded());
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(privateK);
        signature.update(data);
        return Base64.encodeBase64String(signature.sign());
    }

    /**
     * <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, PublicKey publicKey, String sign)
            throws Exception {
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(publicKey.getEncoded());
        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(Base64.decodeBase64(sign));
    }

    /**
     * <P>
     * 私钥解密
     * </p>
     *
     * @param encryptedData 已加密数据
     * @param privateKey 私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(byte[] encryptedData, PrivateKey privateKey)
            throws Exception {
        Cipher cipher = getCipher(privateKey, Cipher.DECRYPT_MODE);
        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 decryptedData;
    }

    /**
     * <p>
     * 公钥解密
     * </p>
     *
     * @param encryptedData 已加密数据
     * @param publicKey 公钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPublicKey(byte[] encryptedData, PublicKey publicKey)
            throws Exception {
        Cipher cipher = getCipher(publicKey, Cipher.DECRYPT_MODE);

        int inputLen = encryptedData.length;
        ByteBuffer buffer = ByteBuffer.allocate(MAX_ENCRYPT_BLOCK);
        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);
            }
            buffer.put(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        buffer.flip();
        byte[] dst = new byte[buffer.limit()];
        buffer.get(dst, 0, buffer.limit());
        return dst;
    }

    /**
     * <p>
     * 公钥加密
     * </p>
     *
     * @param data 源数据
     * @param publicKey 公钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPublicKey(byte[] data, PublicKey publicKey)
            throws Exception {
        Cipher cipher = getCipher(publicKey, Cipher.ENCRYPT_MODE);
        int inputLen = data.length;
        ByteBuffer buffer = ByteBuffer.allocate(MAX_ENCRYPT_BLOCK);
        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);
            }
            buffer.put(cache);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        buffer.flip();
        byte[] dst = new byte[buffer.limit()];
        buffer.get(dst, 0, buffer.limit());
        return dst;
    }

    /**
     * <p>
     * 私钥加密
     * </p>
     *
     * @param data 源数据
     * @param privateKey 私钥(BASE64编码)
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] data, PrivateKey privateKey)
            throws Exception {
        Cipher cipher = getCipher(privateKey, Cipher.ENCRYPT_MODE);
        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 encryptedData;
    }


    public static void main(String[] args) throws Exception {
        String str = "srcbabababababab";
        File privateKeyFile = new File("/Volumes/Media/Workspace/美亚DataHub/id_rsa.keystore");
        File publicKeyFile = new File("/Volumes/Media/Workspace/美亚DataHub/id_rsa.keystore.pub");

        Map<String, Object> keyPair = genFileKeyPair(privateKeyFile);
        PrivateKey privateKey = (PrivateKey) keyPair.get(PRIVATE_KEY);
        PublicKey publicKeyX = (PublicKey) keyPair.get(PUBLIC_KEY);

        PublicKey publicKey = genPublicKey(publicKeyFile);

        System.out.println("====== encoding by private key, decoding by public key======");
        byte[] x = encryptByPrivateKey(str.getBytes(), privateKey);
        System.out.println("encode: " + Base64.encodeBase64String(x));
        System.out.println("decode: " + new String(decryptByPublicKey(x, publicKeyX)));
        System.out.println("decode: " + new String(decryptByPublicKey(x, publicKey)));


        System.out.println("====== encoding by public key, decoding by private key======");
        x = encryptByPublicKey(str.getBytes(), publicKey);
        System.out.println("encode: " + Base64.encodeBase64String(x));
        System.out.println("decode: " + new String(decryptByPrivateKey(x, privateKey)));

        System.out.println("====== encoding by public key, decoding by private key======");
        x = encryptByPublicKey(str.getBytes(), publicKey);
        System.out.println("encode: " + Base64.encodeBase64String(x));
        System.out.println("encode: " + Base64.encodeBase64String(x));
        System.out.println("encode: " + Base64.encodeBase64String(x));
        System.out.println("decode: " + new String(decryptByPrivateKey(x, privateKey)));

        System.out.println("======================");

    }

}