package com.mixsmart.security;

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.HashMap;
import java.util.Map;

/**
 * RSA安全编码组件
 *
 * @version 1.0
 * @since 1.0
 */
public abstract class RSACoder extends Coder{

	public static final String KEY_ALGORITHM = "RSA";
    public static final String SIGNATURE_ALGORITHM = "MD5withRSA";
 
    private static final String PUBLIC_KEY = "RSAPublicKey";
    private static final String PRIVATE_KEY = "RSAPrivateKey";
 
    /**
     * 用私钥对信息生成数字签名
     * 
     * @param data
     *            加密数据
     * @param privateKey
     *            私钥
     * 
     * @return 返回数字签名
     * @throws Exception
     */
    public static String sign(byte[] data, String privateKey) throws Exception {
        // 解密由base64编码的私钥
        byte[] keyBytes = decryptBASE64(privateKey);
        // 构造PKCS8EncodedKeySpec对象
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        // KEY_ALGORITHM 指定的加密算法
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        // 取私钥匙对象
        PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 用私钥对信息生成数字签名
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(priKey);
        signature.update(data);
        return encryptBASE64(signature.sign());
    }
 
    /**
     * 校验数字签名
     * 
     * @param data
     *            加密数据
     * @param publicKey
     *            公钥
     * @param sign
     *            数字签名
     * 
     * @return 校验成功返回true 失败返回false
     * @throws Exception
     * 
     */
    public static boolean verify(byte[] data, String publicKey, String sign)
            throws Exception {
 
        // 解密由base64编码的公钥
        byte[] keyBytes = decryptBASE64(publicKey);
 
        // 构造X509EncodedKeySpec对象
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
 
        // KEY_ALGORITHM 指定的加密算法
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
 
        // 取公钥匙对象
        PublicKey pubKey = keyFactory.generatePublic(keySpec);
 
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(pubKey);
        signature.update(data);
 
        // 验证签名是否正常
        return signature.verify(decryptBASE64(sign));
    }
 
   /**
    * 解密<br>
    * 用私钥解密
    * @param data
    * @param key
    * @return 返回字节数组
    * @throws Exception
    */
    public static byte[] decryptByPrivateKey(byte[] data, String key)
            throws Exception {
        // 对密钥解密
        byte[] keyBytes = decryptBASE64(key);
 
        // 取得私钥
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
 
        // 对数据解密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
 
        return cipher.doFinal(data);
    }
 
    /**
     * 解密<br>
     * 用私钥解密
     * 
     * @param data
     * @param key
     * @return 返回字节数组
     * @throws Exception
     */
    public static byte[] decryptByPublicKey(byte[] data, String key)
            throws Exception {
        // 对密钥解密
        byte[] keyBytes = decryptBASE64(key);
 
        // 取得公钥
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicKey = keyFactory.generatePublic(x509KeySpec);
 
        // 对数据解密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, publicKey);
 
        return cipher.doFinal(data);
    }
 
    /**
     * 加密<br>
     * 用公钥加密
     * 
     * @param data
     * @param key
     * @return 返回字节数组
     * @throws Exception
     */
    public static byte[] encryptByPublicKey(byte[] data, String key)
            throws Exception {
        // 对公钥解密
        byte[] keyBytes = decryptBASE64(key);
 
        // 取得公钥
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicKey = keyFactory.generatePublic(x509KeySpec);
 
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
 
        return cipher.doFinal(data);
    }
 
    /**
     * 加密<br>
     * 用私钥加密
     * 
     * @param data
     * @param key
     * @return 返回字节数组
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] data, String key)
            throws Exception {
        // 对密钥解密
        byte[] keyBytes = decryptBASE64(key);
 
        // 取得私钥
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
 
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
 
        return cipher.doFinal(data);
    }
 
    /**
     * 取得私钥
     * 
     * @param keyMap
     * @return 返回私钥
     * @throws Exception
     */
    public static String getPrivateKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PRIVATE_KEY);
 
        return encryptBASE64(key.getEncoded());
    }
 
    /**
     * 取得公钥
     * 
     * @param keyMap
     * @return 返回公钥
     * @throws Exception
     */
    public static String getPublicKey(Map<String, Object> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PUBLIC_KEY);
 
        return encryptBASE64(key.getEncoded());
    }
 
    /**
     * 初始化密钥
     * 
     * @return 返回初始化密钥
     * @throws Exception
     */
    public static Map<String, Object> initKey() throws Exception {
        KeyPairGenerator keyPairGen = KeyPairGenerator
                .getInstance(KEY_ALGORITHM);
        keyPairGen.initialize(1024);
        KeyPair keyPair = keyPairGen.generateKeyPair();
        // 公钥
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        // 私钥
        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;
    }
}