using System;
using System.Collections.Generic;
using System.Text;

using System.Security.Cryptography;

namespace Sog.Crypto
{
    /// <summary>
    /// mono(.NetFramework 2.0) crypto api 和 BouncyCastle兼容性处理
    /// </summary>
    public static class CryptoConvertUtils
    {
        /*
        /// <summary>
        /// 根据mod，exp生成publickey
        /// </summary>
        /// <param name="modulus"></param>
        /// <param name="exponent"></param>
        /// <returns></returns>
        /// RSAParameters
        public static RsaKeyParameters GetRsaPublicKey(byte[] modulus, byte[] exponent)
        {
            RSAParameters
            return new RsaKeyParameters(
                false,
                new BigInteger(1, modulus),
                new BigInteger(1, exponent));
        }

        /// <summary>
        /// 公钥解密
        /// </summary>
        /// <param name="encryptedData"></param>
        /// <param name="publicParameters"></param>
        /// <returns></returns>
        public static byte[] DecryptWithPublicKey(byte[] encryptedData, RsaKeyParameters publicParameters)
        {
            IAsymmetricBlockCipher eng = new Pkcs1Encoding(new RsaEngine());
            eng.Init(false, publicParameters);

            byte[] data = eng.ProcessBlock(encryptedData, 0, encryptedData.Length);

            return data;
        }


        public static byte[] DecryptWithPublicKey(byte[] encryptedData, byte[] modulus, byte[] exponent)
        {
            RsaKeyParameters publicParameters = GetRsaPublicKey(modulus,exponent);

            return DecryptWithPublicKey(encryptedData, publicParameters);
        }

        /// <summary>
        /// 公钥加密
        /// </summary>
        /// <param name="data"></param>
        /// <param name="publicParameters">公钥参数</param>
        /// <returns>加密后的数据</returns>
        public static byte[] EncryptWithPublicKey(byte[] data, RsaKeyParameters publicParameters)
        {
            IAsymmetricBlockCipher eng = new Pkcs1Encoding(new RsaEngine());
            eng.Init(true, publicParameters);

            byte[] encryptedData = eng.ProcessBlock(data, 0, data.Length);

            return encryptedData;
        }

        public static byte[] EncryptWithPublicKey(byte[] data, byte[] modulus, byte[] exponent)
        {
            RsaKeyParameters publicParameters = GetRsaPublicKey(modulus, exponent);

            return EncryptWithPublicKey(data, publicParameters);
        }
        */

        /// <summary>   
        /// 对ExportCspBlob(false)方法到处的私钥进行解析，提取私钥参数   
        /// </summary>   
        /// <param name="cspblobPublicKey">RSA.ExportCspBlob(false)得到的包含私钥信息</param>   
        /// <returns>公钥模数</returns>   
        public static byte[] PublicKeyResolve(byte[] cspblobPublicKey)
        {
            byte[] modulus = new byte[128];
            Array.Reverse(cspblobPublicKey, 0, cspblobPublicKey.Length);
            Buffer.BlockCopy(cspblobPublicKey, 0, modulus, 0, 128);
            return modulus;
        }

        /// <summary>   
        /// 对ExportCspBlob(true)方法到处的私钥进行解析，提取私钥参数   
        /// </summary>   
        /// <param name="cspblobPrivateKey">RSA.ExportCspBlob(true)得到的包含私钥信息</param>   
        /// <returns>私钥参数</returns>   
        public static Dictionary<string, byte[]> PrivateKeyResolve(byte[] cspblobPrivateKey)
        {
            Dictionary<string, byte[]> privateKeyParameters = new Dictionary<string, byte[]>();

            Array.Reverse(cspblobPrivateKey, 0, cspblobPrivateKey.Length);
            int offset = 0;
            byte[] part = new byte[128];
            Buffer.BlockCopy(cspblobPrivateKey, offset, part, offset, part.Length);
            privateKeyParameters.Add("D", part);

            offset += part.Length;
            part = new byte[64];
            Buffer.BlockCopy(cspblobPrivateKey, offset, part, 0, part.Length);
            privateKeyParameters.Add("INVERSEQ", part);

            offset += part.Length;
            part = new byte[64];
            Buffer.BlockCopy(cspblobPrivateKey, offset, part, 0, part.Length);
            privateKeyParameters.Add("DQ", part);

            offset += part.Length;
            part = new byte[64];
            Buffer.BlockCopy(cspblobPrivateKey, offset, part, 0, part.Length);
            privateKeyParameters.Add("DP", part);

            offset += part.Length;
            part = new byte[64];
            Buffer.BlockCopy(cspblobPrivateKey, offset, part, 0, part.Length);
            privateKeyParameters.Add("Q", part);

            offset += part.Length;
            part = new byte[64];
            Buffer.BlockCopy(cspblobPrivateKey, offset, part, 0, part.Length);
            privateKeyParameters.Add("P", part);

            offset += part.Length;
            part = new byte[128];
            Buffer.BlockCopy(cspblobPrivateKey, offset, part, 0, part.Length);
            privateKeyParameters.Add("MODULUS", part);
            return privateKeyParameters;
        }

        /// <summary>
        /// 数组转成16进制字符串
        /// </summary>
        /// <param name="bytes"></param>
        /// <returns></returns>
        public static string ToHexString(byte[] bytes) // 0xae00cf => "AE00CF "
        {
            string hexString = string.Empty;

            if (bytes != null)
            {
                StringBuilder strB = new StringBuilder();

                for (int i = 0; i < bytes.Length; i++)
                {
                    strB.Append(bytes[i].ToString("X2"));
                }
                hexString = strB.ToString();
            }
            return hexString;
        }

        public static byte[] EncryptWithPublicKeyWithChewKeongTANBigInteger(byte[] data, byte[] modulus, byte[] exponent)
        {
            ChewKeongTAN.BigInteger bi_n = new ChewKeongTAN.BigInteger(modulus);
            ChewKeongTAN.BigInteger bi_e = new ChewKeongTAN.BigInteger(exponent);

            ChewKeongTAN.BigInteger biText = new ChewKeongTAN.BigInteger(data);
            ChewKeongTAN.BigInteger biEnText = biText.modPow(bi_e, bi_n);


            byte[] outbytes = biEnText.getBytes();

            //TraceLog.Trace("EncryptWithPublicKeyWithChewKeongTANBigInteger entext {0}", biEnText.ToString());
            return outbytes;
        }
    }
}