/*
 * FileName：RSACoder.java 
 * <p>
 * Copyright (c) 2017-2020, <a href="http://www.webcsn.com">hermit (794890569@qq.com)</a>.
 * <p>
 * Licensed under the GNU General Public License, Version 3 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p>
 * http://www.gnu.org/licenses/gpl-3.0.html
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 */
package cn.com.lzt.common.util.coder;

import cn.com.lzt.common.util.security.SecurityCoder;

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
 * 
 * @author ShenHuaJie
 * @version 1.0
 * @since 1.0
 */
public abstract class RSACoder extends SecurityCoder {

	/**
	 * 数字签名 密钥算法
	 */
	public static final String KEY_ALGORITHM = "RSA";

	/**
	 * 数字签名 签名/验证算法
	 */
	public static final String SIGNATURE_ALGORITHM = "SHA1withRSA";

	/**
	 * 公钥
	 */
	private static final String PUBLIC_KEY = "RSAPublicKey";

	/**
	 * 私钥
	 */
	private static final String PRIVATE_KEY = "RSAPrivateKey";

	/**
	 * RSA密钥长度 默认1024位， 密钥长度必须是64的倍数， 范围在512至65536位之间。
	 */
	private static final int KEY_SIZE = 512;

	/**
	 * 签名
	 * 
	 * @param data 待签名数据
	 * @param privateKey 私钥
	 * @return byte[] 数字签名
	 * @throws Exception
	 */
	public static byte[] sign(byte[] data, byte[] privateKey) throws Exception {
		// 转换私钥材料
		PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(privateKey);
		// 实例化密钥工厂
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		// 取私钥匙对象
		PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);
		// 实例化Signature
		Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
		// 初始化Signature
		signature.initSign(priKey);
		// 更新
		signature.update(data);
		// 签名
		return signature.sign();
	}

	/**
	 * 校验
	 * 
	 * @param data 待校验数据
	 * @param publicKey 公钥
	 * @param sign 数字签名
	 * @return boolean 校验成功返回true 失败返回false
	 * @throws Exception
	 */
	public static boolean verify(byte[] data, byte[] publicKey, byte[] sign) throws Exception {
		// 转换公钥材料
		X509EncodedKeySpec keySpec = new X509EncodedKeySpec(publicKey);
		// 实例化密钥工厂
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		// 生成公钥
		PublicKey pubKey = keyFactory.generatePublic(keySpec);
		// 实例化Signature
		Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
		// 初始化Signature
		signature.initVerify(pubKey);
		// 更新
		signature.update(data);
		// 验证
		return signature.verify(sign);
	}

	/**
	 * 私钥解密
	 * 
	 * @param data 待解密数据
	 * @param key 私钥
	 * @return byte[] 解密数据
	 * @throws Exception
	 */
	public static byte[] decryptByPrivateKey(byte[] data, byte[] key) throws Exception {
		// 取得私钥
		PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(key);
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		// 生成私钥
		PrivateKey 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);
	}

	/**
	 * 公钥解密
	 * 
	 * @param data 待解密数据
	 * @param key 公钥
	 * @return byte[] 解密数据
	 * @throws Exception
	 */
	public static byte[] decryptByPublicKey(byte[] data, byte[] key) throws Exception {
		// 取得公钥
		X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(key);
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		// 生成公钥
		PublicKey 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);
	}

	/**
	 * 公钥加密
	 * 
	 * @param data 待加密数据
	 * @param key 公钥
	 * @return byte[] 加密数据
	 * @throws Exception
	 */
	public static byte[] encryptByPublicKey(byte[] data, byte[] key) throws Exception {
		// 取得公钥
		X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(key);
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		PublicKey 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);
	}

	/**
	 * 私钥加密
	 * 
	 * @param data 待加密数据
	 * @param key 私钥
	 * @return byte[] 加密数据
	 * @throws Exception
	 */
	public static byte[] encryptByPrivateKey(byte[] data, byte[] key) throws Exception {
		// 取得私钥
		PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(key);
		KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
		// 生成私钥
		PrivateKey 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
	 * @throws Exception
	 */
	public static byte[] getPrivateKey(Map<String, Object> keyMap) throws Exception {
		Key key = (Key) keyMap.get(PRIVATE_KEY);
		return key.getEncoded();
	}

	/**
	 * 取得公钥
	 * 
	 * @param keyMap
	 * @return
	 * @throws Exception
	 */
	public static byte[] getPublicKey(Map<String, Object> keyMap) throws Exception {
		Key key = (Key) keyMap.get(PUBLIC_KEY);
		return key.getEncoded();
	}

	/**
	 * 初始化密钥
	 * 
	 * @return Map 密钥对儿 Map
	 * @throws Exception
	 */
	public static Map<String, Object> initKey() throws Exception {
		// 实例化密钥对儿生成器
		KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
		// 初始化密钥对儿生成器
		keyPairGen.initialize(KEY_SIZE);
		// 生成密钥对儿
		KeyPair keyPair = keyPairGen.generateKeyPair();
		// 公钥
		RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
		// 私钥
		RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
		// 封装密钥
		Map<String, Object> keyMap = new HashMap<String, Object>(2);
		keyMap.put(PUBLIC_KEY, publicKey);
		keyMap.put(PRIVATE_KEY, privateKey);
		return keyMap;
	}
}