/**
 * 2011-01-11
 */
package org.ibase4j.core.support.security.coder;

import org.ibase4j.core.support.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;
    }
}
