using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;

namespace POSV.Utils
{
    /// <summary>  
    /// 类名：RSAFromPkcs8  
    /// 功能：RSA加密、解密、签名、验签  
    /// 详细：该类对Java生成的密钥进行解密和签名以及验签专用类，不需要修改  
    /// 说明：  
    /// 以下代码只是为了方便商户测试而提供的样例代码，商户可以根据自己网站的需要，按照技术文档编写,并非一定要使用该代码。  
    /// </summary>  
    public sealed class RSAFromPkcs8
    {
        /// <summary>  
        /// 签名  
        /// </summary>  
        /// <param name="content">待签名字符串</param>  
        /// <param name="privateKey">私钥</param>  
        /// <param name="input_charset">编码格式</param>  
        /// <returns>签名后字符串</returns>  
        public static string sign(string content , string privateKey , string input_charset,string sign_type = "RSA")
        {
            byte[] Data = Encoding.GetEncoding(input_charset).GetBytes(content);
            RSACryptoServiceProvider rsa = DecodePemPrivateKey(privateKey);

            if ("RSA".Equals(sign_type))
            {
                using (var sha1 = new SHA1CryptoServiceProvider())
                {
                    byte[] signData = rsa.SignData(Data, sha1);
                    return Convert.ToBase64String(signData);
                }
            }
            else
            {
                using (var sha256 = new SHA256CryptoServiceProvider())
                {
                    byte[] signData = rsa.SignData(Data, sha256);
                    return Convert.ToBase64String(signData);
                }
            }            
        }

        /// <summary>  
        /// 验签  
        /// </summary>  
        /// <param name="content">待验签字符串</param>  
        /// <param name="signedString">签名</param>  
        /// <param name="publicKey">公钥</param>  
        /// <param name="input_charset">编码格式</param>  
        /// <returns>true(通过)，false(不通过)</returns>  
        public static bool verify(string content , string signedString , string publicKey , string input_charset, string sign_type = "RSA")
        {
            bool result = false;
            byte[] Data = Encoding.GetEncoding(input_charset).GetBytes(content);
            byte[] data = Convert.FromBase64String(signedString);
            RSAParameters paraPub = ConvertFromPublicKey(publicKey);
            RSACryptoServiceProvider rsaPub = new RSACryptoServiceProvider();
            rsaPub.ImportParameters(paraPub);

            if ("RSA".Equals(sign_type))
            {
                using (var sha1 = new SHA1CryptoServiceProvider())
                {
                    result = rsaPub.VerifyData(Data, sha1, data);
                    return result;
                }
            }
            else
            {
                using (var sha256 = new SHA256CryptoServiceProvider())
                {
                    result = rsaPub.VerifyData(Data, sha256, data);
                    return result;
                }
            }
        }

        /// <summary>  
        /// 加密  
        /// </summary>  
        /// <param name="resData">需要加密的字符串</param>  
        /// <param name="publicKey">公钥</param>  
        /// <param name="input_charset">编码格式</param>  
        /// <returns>明文</returns>  
        public static string encryptData(string resData , string publicKey , string input_charset)
        {
            byte[] DataToEncrypt = Encoding.ASCII.GetBytes(resData);
            string result = encrypt(DataToEncrypt , publicKey , input_charset);
            return result;
        }


        /// <summary>  
        /// 解密  
        /// </summary>  
        /// <param name="resData">加密字符串</param>  
        /// <param name="privateKey">私钥</param>  
        /// <param name="input_charset">编码格式</param>  
        /// <returns>明文</returns>  
        public static string decryptData(string resData , string privateKey , string input_charset)
        {
            byte[] DataToDecrypt = Convert.FromBase64String(resData);
            string result = "";
            for (int j = 0; j < DataToDecrypt.Length / 128; j++)
            {
                byte[] buf = new byte[128];
                for (int i = 0; i < 128; i++)
                {

                    buf[i] = DataToDecrypt[i + 128 * j];
                }
                result += decrypt(buf , privateKey , input_charset);
            }
            return result;
        }

        #region 内部方法  

        private static string encrypt(byte[] data , string publicKey , string input_charset)
        {
            RSACryptoServiceProvider rsa = DecodePemPublicKey(publicKey);
            SHA1 sh = new SHA1CryptoServiceProvider();
            byte[] result = rsa.Encrypt(data , false);

            return Convert.ToBase64String(result);
        }

        private static string decrypt(byte[] data , string privateKey , string input_charset)
        {
            string result = "";
            RSACryptoServiceProvider rsa = DecodePemPrivateKey(privateKey);
            SHA1 sh = new SHA1CryptoServiceProvider();
            byte[] source = rsa.Decrypt(data , false);
            char[] asciiChars = new char[Encoding.GetEncoding(input_charset).GetCharCount(source , 0 , source.Length)];
            Encoding.GetEncoding(input_charset).GetChars(source , 0 , source.Length , asciiChars , 0);
            result = new string(asciiChars);
            //result = ASCIIEncoding.ASCII.GetString(source);  
            return result;
        }

        private static RSACryptoServiceProvider DecodePemPublicKey(String pemstr)
        {
            byte[] pkcs8publickkey;
            pkcs8publickkey = Convert.FromBase64String(pemstr);
            if (pkcs8publickkey != null)
            {
                RSACryptoServiceProvider rsa = DecodeRSAPublicKey(pkcs8publickkey);
                return rsa;
            }
            else
                return null;
        }

        private static RSACryptoServiceProvider DecodePemPrivateKey(String pemstr)
        {
            byte[] pkcs8privatekey;
            pkcs8privatekey = Convert.FromBase64String(pemstr);
            if (pkcs8privatekey != null)
            {
                RSACryptoServiceProvider rsa = DecodePrivateKeyInfo(pkcs8privatekey);
                return rsa;
            }
            else
                return null;
        }

        private static RSACryptoServiceProvider DecodePrivateKeyInfo(byte[] pkcs8)
        {
            byte[] SeqOID = { 0x30 , 0x0D , 0x06 , 0x09 , 0x2A , 0x86 , 0x48 , 0x86 , 0xF7 , 0x0D , 0x01 , 0x01 , 0x01 , 0x05 , 0x00 };
            byte[] seq = new byte[15];

            MemoryStream mem = new MemoryStream(pkcs8);
            int lenstream = (int)mem.Length;
            BinaryReader binr = new BinaryReader(mem);    //wrap Memory Stream with BinaryReader for easy reading  
            byte bt = 0;
            ushort twobytes = 0;

            try
            {
                twobytes = binr.ReadUInt16();
                if (twobytes == 0x8130)    //data read as little endian order (actual data order for Sequence is 30 81)  
                    binr.ReadByte();    //advance 1 byte  
                else if (twobytes == 0x8230)
                    binr.ReadInt16();    //advance 2 bytes  
                else
                    return null;

                bt = binr.ReadByte();
                if (bt != 0x02)
                    return null;

                twobytes = binr.ReadUInt16();

                if (twobytes != 0x0001)
                    return null;

                seq = binr.ReadBytes(15);        //read the Sequence OID  
                if (!CompareBytearrays(seq , SeqOID))    //make sure Sequence for OID is correct  
                    return null;

                bt = binr.ReadByte();
                if (bt != 0x04)    //expect an Octet string  
                    return null;

                bt = binr.ReadByte();        //read next byte, or next 2 bytes is  0x81 or 0x82; otherwise bt is the byte count  
                if (bt == 0x81)
                    binr.ReadByte();
                else
                    if (bt == 0x82)
                    binr.ReadUInt16();
                //------ at this stage, the remaining sequence should be the RSA private key  

                byte[] rsaprivkey = binr.ReadBytes((int)(lenstream - mem.Position));
                RSACryptoServiceProvider rsacsp = DecodeRSAPrivateKey(rsaprivkey);
                return rsacsp;
            }

            catch (Exception)
            {
                return null;
            }

            finally { binr.Close(); }

        }

        private static bool CompareBytearrays(byte[] a , byte[] b)
        {
            if (a.Length != b.Length)
                return false;
            int i = 0;
            foreach (byte c in a)
            {
                if (c != b[i])
                    return false;
                i++;
            }
            return true;
        }

        private static RSACryptoServiceProvider DecodeRSAPublicKey(byte[] publickey)
        {
            // encoded OID sequence for  PKCS #1 rsaEncryption szOID_RSA_RSA = "1.2.840.113549.1.1.1"  
            byte[] SeqOID = { 0x30 , 0x0D , 0x06 , 0x09 , 0x2A , 0x86 , 0x48 , 0x86 , 0xF7 , 0x0D , 0x01 , 0x01 , 0x01 , 0x05 , 0x00 };
            byte[] seq = new byte[15];
            // ---------  Set up stream to read the asn.1 encoded SubjectPublicKeyInfo blob  ------  
            MemoryStream mem = new MemoryStream(publickey);
            BinaryReader binr = new BinaryReader(mem);    //wrap Memory Stream with BinaryReader for easy reading  
            byte bt = 0;
            ushort twobytes = 0;

            try
            {

                twobytes = binr.ReadUInt16();
                if (twobytes == 0x8130) //data read as little endian order (actual data order for Sequence is 30 81)  
                    binr.ReadByte();    //advance 1 byte  
                else if (twobytes == 0x8230)
                    binr.ReadInt16();   //advance 2 bytes  
                else
                    return null;

                seq = binr.ReadBytes(15);       //read the Sequence OID  
                if (!CompareBytearrays(seq , SeqOID))    //make sure Sequence for OID is correct  
                    return null;

                twobytes = binr.ReadUInt16();
                if (twobytes == 0x8103) //data read as little endian order (actual data order for Bit String is 03 81)  
                    binr.ReadByte();    //advance 1 byte  
                else if (twobytes == 0x8203)
                    binr.ReadInt16();   //advance 2 bytes  
                else
                    return null;

                bt = binr.ReadByte();
                if (bt != 0x00)     //expect null byte next  
                    return null;

                twobytes = binr.ReadUInt16();
                if (twobytes == 0x8130) //data read as little endian order (actual data order for Sequence is 30 81)  
                    binr.ReadByte();    //advance 1 byte  
                else if (twobytes == 0x8230)
                    binr.ReadInt16();   //advance 2 bytes  
                else
                    return null;

                twobytes = binr.ReadUInt16();
                byte lowbyte = 0x00;
                byte highbyte = 0x00;

                if (twobytes == 0x8102) //data read as little endian order (actual data order for Integer is 02 81)  
                    lowbyte = binr.ReadByte();  // read next bytes which is bytes in modulus  
                else if (twobytes == 0x8202)
                {
                    highbyte = binr.ReadByte(); //advance 2 bytes  
                    lowbyte = binr.ReadByte();
                }
                else
                    return null;
                byte[] modint = { lowbyte , highbyte , 0x00 , 0x00 };   //reverse byte order since asn.1 key uses big endian order  
                int modsize = BitConverter.ToInt32(modint , 0);

                byte firstbyte = binr.ReadByte();
                binr.BaseStream.Seek(-1 , SeekOrigin.Current);

                if (firstbyte == 0x00)
                {   //if first byte (highest order) of modulus is zero, don't include it  
                    binr.ReadByte();    //skip this null byte  
                    modsize -= 1;   //reduce modulus buffer size by 1  
                }

                byte[] modulus = binr.ReadBytes(modsize);   //read the modulus bytes  

                if (binr.ReadByte() != 0x02)            //expect an Integer for the exponent data  
                    return null;
                int expbytes = (int)binr.ReadByte();        // should only need one byte for actual exponent data (for all useful values)  
                byte[] exponent = binr.ReadBytes(expbytes);

                // ------- create RSACryptoServiceProvider instance and initialize with public key -----  
                RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
                RSAParameters RSAKeyInfo = new RSAParameters();
                RSAKeyInfo.Modulus = modulus;
                RSAKeyInfo.Exponent = exponent;
                RSA.ImportParameters(RSAKeyInfo);
                return RSA;
            }
            catch (Exception)
            {
                return null;
            }

            finally { binr.Close(); }

        }

        private static RSACryptoServiceProvider DecodeRSAPrivateKey(byte[] privkey)
        {
            byte[] MODULUS, E, D, P, Q, DP, DQ, IQ;

            // ---------  Set up stream to decode the asn.1 encoded RSA private key  ------  
            MemoryStream mem = new MemoryStream(privkey);
            BinaryReader binr = new BinaryReader(mem);    //wrap Memory Stream with BinaryReader for easy reading  
            byte bt = 0;
            ushort twobytes = 0;
            int elems = 0;
            try
            {
                twobytes = binr.ReadUInt16();
                if (twobytes == 0x8130)    //data read as little endian order (actual data order for Sequence is 30 81)  
                    binr.ReadByte();    //advance 1 byte  
                else if (twobytes == 0x8230)
                    binr.ReadInt16();    //advance 2 bytes  
                else
                    return null;

                twobytes = binr.ReadUInt16();
                if (twobytes != 0x0102)    //version number  
                    return null;
                bt = binr.ReadByte();
                if (bt != 0x00)
                    return null;


                //------  all private key components are Integer sequences ----  
                elems = GetIntegerSize(binr);
                MODULUS = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                E = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                D = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                P = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                Q = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                DP = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                DQ = binr.ReadBytes(elems);

                elems = GetIntegerSize(binr);
                IQ = binr.ReadBytes(elems);

                // ------- create RSACryptoServiceProvider instance and initialize with public key -----  
                RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
                RSAParameters RSAparams = new RSAParameters();
                RSAparams.Modulus = MODULUS;
                RSAparams.Exponent = E;
                RSAparams.D = D;
                RSAparams.P = P;
                RSAparams.Q = Q;
                RSAparams.DP = DP;
                RSAparams.DQ = DQ;
                RSAparams.InverseQ = IQ;
                RSA.ImportParameters(RSAparams);
                return RSA;
            }
            catch (Exception)
            {
                return null;
            }
            finally { binr.Close(); }
        }

        private static int GetIntegerSize(BinaryReader binr)
        {
            byte bt = 0;
            byte lowbyte = 0x00;
            byte highbyte = 0x00;
            int count = 0;
            bt = binr.ReadByte();
            if (bt != 0x02)        //expect integer  
                return 0;
            bt = binr.ReadByte();

            if (bt == 0x81)
                count = binr.ReadByte();    // data size in next byte  
            else
                if (bt == 0x82)
            {
                highbyte = binr.ReadByte();    // data size in next 2 bytes  
                lowbyte = binr.ReadByte();
                byte[] modint = { lowbyte , highbyte , 0x00 , 0x00 };
                count = BitConverter.ToInt32(modint , 0);
            }
            else
            {
                count = bt;        // we already have the data size  
            }



            while (binr.ReadByte() == 0x00)
            {    //remove high order zeros in data  
                count -= 1;
            }
            binr.BaseStream.Seek(-1 , SeekOrigin.Current);        //last ReadByte wasn't a removed zero, so back up a byte  
            return count;
        }

        #endregion

        #region 解析.net 生成的Pem  
        private static RSAParameters ConvertFromPublicKey(string pemFileConent)
        {

            byte[] keyData = Convert.FromBase64String(pemFileConent);
            if (keyData.Length < 162)
            {
                throw new ArgumentException("pem file content is incorrect.");
            }
            byte[] pemModulus = new byte[128];
            byte[] pemPublicExponent = new byte[3];
            Array.Copy(keyData , 29 , pemModulus , 0 , 128);
            Array.Copy(keyData , 159 , pemPublicExponent , 0 , 3);
            RSAParameters para = new RSAParameters();
            para.Modulus = pemModulus;
            para.Exponent = pemPublicExponent;
            return para;
        }

        private static RSAParameters ConvertFromPrivateKey(string pemFileConent)
        {
            byte[] keyData = Convert.FromBase64String(pemFileConent);
            if (keyData.Length < 609)
            {
                throw new ArgumentException("pem file content is incorrect.");
            }

            int index = 11;
            byte[] pemModulus = new byte[128];
            Array.Copy(keyData , index , pemModulus , 0 , 128);

            index += 128;
            index += 2;//141  
            byte[] pemPublicExponent = new byte[3];
            Array.Copy(keyData , index , pemPublicExponent , 0 , 3);

            index += 3;
            index += 4;//148  
            byte[] pemPrivateExponent = new byte[128];
            Array.Copy(keyData , index , pemPrivateExponent , 0 , 128);

            index += 128;
            index += ((int)keyData[index + 1] == 64 ? 2 : 3);//279  
            byte[] pemPrime1 = new byte[64];
            Array.Copy(keyData , index , pemPrime1 , 0 , 64);

            index += 64;
            index += ((int)keyData[index + 1] == 64 ? 2 : 3);//346  
            byte[] pemPrime2 = new byte[64];
            Array.Copy(keyData , index , pemPrime2 , 0 , 64);

            index += 64;
            index += ((int)keyData[index + 1] == 64 ? 2 : 3);//412/413  
            byte[] pemExponent1 = new byte[64];
            Array.Copy(keyData , index , pemExponent1 , 0 , 64);

            index += 64;
            index += ((int)keyData[index + 1] == 64 ? 2 : 3);//479/480  
            byte[] pemExponent2 = new byte[64];
            Array.Copy(keyData , index , pemExponent2 , 0 , 64);

            index += 64;
            index += ((int)keyData[index + 1] == 64 ? 2 : 3);//545/546  
            byte[] pemCoefficient = new byte[64];
            Array.Copy(keyData , index , pemCoefficient , 0 , 64);

            RSAParameters para = new RSAParameters();
            para.Modulus = pemModulus;
            para.Exponent = pemPublicExponent;
            para.D = pemPrivateExponent;
            para.P = pemPrime1;
            para.Q = pemPrime2;
            para.DP = pemExponent1;
            para.DQ = pemExponent2;
            para.InverseQ = pemCoefficient;
            return para;
        }
        #endregion

    }
}





//static void Main(string[] arg)
//{

//    /**RSA加密测试,RSA中的密钥对通过SSL工具生成，生成命令如下： 
//     * 1 生成RSA私钥： 
//     * openssl genrsa -out rsa_private_key.pem 1024 
//     *2 生成RSA公钥 
//     * openssl rsa -in rsa_private_key.pem -pubout -out rsa_public_key.pem 
//     * 
//     * 3 将RSA私钥转换成PKCS8格式 
//     * openssl pkcs8 -topk8 -inform PEM -in rsa_private_key.pem -outform PEM -nocrypt -out rsa_pub_pk8.pem 
//     * 
//     * 直接打开rsa_private_key.pem和rsa_pub_pk8.pem文件就可以获取密钥对内容，获取密钥对内容组成字符串时，注意将换行符删除 
//     * */

//    string publickey = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDzOqfNunFxFtCZPlq7fO/jWwjqmTvAooVBB4y87BizSZ9dl/F7FpAxYc6MmX2TqivCvvORXgdlYdFWAhzXOnIUv9OGG///WPLe9TMs9kIwAZ/APUXauvC01oFLnYkzwPlAh0tQ1Au9arTE/OG1V1dKgf8BXHLPhKL4BmGBEUZBtQIDAQAB";
//    string privatekey = "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";

//    //加密字符串  
//    string data = "yibao";

//    Console.WriteLine("加密前字符串内容：" + data);
//    //加密  
//    string encrypteddata = RSAFromPkcs8.encryptData(data, publickey, "UTF-8");
//    Console.WriteLine("加密后的字符串为：" + encrypteddata);
//    Console.WriteLine("解密后的字符串内容：" + RSAFromPkcs8.decryptData(encrypteddata, privatekey, "UTF-8"));

//    Console.WriteLine("***********");

//    //解密  
//    string endata = "LpnnvnfA72VnyjboX/OsCPO6FOFXeEnnsKkI7aAEQyVAPfCTfQ43ZYVZVqnADDPMW7VhBXJWyQMAGw2Fh9sS/XLHmO5XW94Yehci6JrJMynePgtIiDysjNA+UlgSTC/MlResNrBm/4MMSPvq0qLwScgpZDynhLsVZk+EQ6G8wgA=";
//    string datamw = RSAFromPkcs8.decryptData(endata, privatekey, "UTF-8");
//    Console.WriteLine("静态加密后的字符串为：" + endata);
//    Console.WriteLine("解密后的字符串内容：" + datamw);

//    //签名  
//    string signdata = "YB010000001441234567286038508081299";
//    Console.WriteLine("签名前的字符串内容：" + signdata);
//    string sign = RSAFromPkcs8.sign(signdata, privatekey, "UTF-8");
//    Console.WriteLine("签名后的字符串：" + sign);

//    Console.ReadLine();
//}