using System;

using System.Text;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(GetPanForUDKDerive("4427808001112223337","01"));//"5215400119168584ADEABFFEE6E97A7B"

    }

    public static string GetPanForUDKDerive(string pan, string panSeqNo)

        {

            if (pan.IndexOf('F') > 0)

                pan = pan.Substring(0, pan.IndexOf('F'));

​

            string temp;

            if (pan.Length <= 16)

            {

                temp = pan.PadLeft(16, '0') + panSeqNo.PadRight(2, '0');

                temp = temp.Substring(temp.Length - 16, 16);

            }

            else

            {

                temp = pan + panSeqNo.PadRight(2, '0');

                if (temp.Length % 2 > 0)

                {

                    temp = "0" + temp;

                }

                byte[] HashCode = new byte[40];

                HashCode = ComputeHashStr(temp).Digest;

                string HashStr = UnPack(HashCode);

                temp = "";

                for (byte i = 0; i < 40 && temp.Length < 16; i++)

                {

                    if (HashStr[i] >= '0' && HashStr[i] <= '9')

                    {

                        temp += HashStr[i];

                    }

                }

                if (temp.Length < 16)

                {

                    for (byte i = 0; i < 40 && temp.Length < 17; i++)

                    {

                        if (HashStr[i] >= 'A' && HashStr[i] <= 'F')

                        {

                            temp += (Convert.ToByte(HashStr[i]) - 65).ToString();

                        }

                    }

                }

            }

            temp += XOR("FFFFFFFFFFFFFFFF", temp);

​

​

​

            return temp;

        }

    public static HashResponse ComputeHashStr(string buffer)

        {

            var res = new HashResponse();

​

            using (var sha1 = System.Security.Cryptography.SHA1.Create())

            {

                res.Digest = sha1.ComputeHash(Pack(buffer));

            }

            res.Length = res.Digest.Length;

            return res;

​

        }

    public class HashResponse

    {

        public int Length { get; set; }

        public byte[] Digest  { get; set; }

    }

    public static string XOR(string s1, string s2)

        {

            if (s1.Length != s2.Length)

                throw new ArgumentException("ByteArray.XOR parameter1 and parameter2 must have equal length");

​

            if ((s1.Length % 2) != 0)

                throw new ArgumentException("ByteArray.XOR invalid length of parameters");

​

            byte[] ba1 = Pack(s1);

            byte[] ba2 = Pack(s2);

​

            byte[] ba = new byte[ba1.Length];

​

            for (int i = 0; i < ba1.Length; i++)

            {

                ba[i] = (byte)(ba1[i] ^ ba2[i]);

            }

​

            return UnPack(ba);

        }

      public static byte[] Pack(string hexData)

        {

            // throw an exception if hexData is not hex encoded

            if (IsHex(hexData) == false)

                throw new FormatException("Non hex digit found");

            // if odd number of characters, throw this

            if (hexData.Length % 2 != 0)

            {

                throw new ArgumentException("Data length is odd");

            }

            byte[] binaryData = new byte[hexData.Length / 2];

            string hex;

            int j = 0;

            for (int i = 0; i < binaryData.Length; i++)

            {

                hex = new String(new Char[] { hexData[j], hexData[j + 1] });

                binaryData[i] = byte.Parse(hex, System.Globalization.NumberStyles.HexNumber);

                j += 2;

            }

            return binaryData;

        }

           public static string UnPack(byte[] binaryData)

        {

            StringBuilder hexData = new StringBuilder();

            foreach (byte binary in binaryData)

            {

                hexData.Append(binary.ToString("X2"));

            }

            return hexData.ToString();

        }

public static bool IsHex(string data)

        {

            if (data == null)

                return false;

            if (data.Length == 0)

                return false;

​

            return System.Text.RegularExpressions.Regex.IsMatch(data, "^[0-9a-fA-F]*$");

        }

}