using System;

using System.Text;

​

public class Program

{

    static string GetHex16(string strText)

    {

        Int64 hashCode = 0;

        if (!string.IsNullOrEmpty(strText))

        {

            //Unicode Encode Covering all characterset

            byte[] byteContents = Encoding.Unicode.GetBytes(strText);

            System.Security.Cryptography.SHA256 hash = new System.Security.Cryptography.SHA256CryptoServiceProvider();

            byte[] hashText = hash.ComputeHash(byteContents);

            //32Byte hashText separate

            //hashCodeStart = 0~7  8Byte

            //hashCodeMedium = 8~23  8Byte

            //hashCodeEnd = 24~31  8Byte

            //and Fold

            Int64 hashCodeStart = BitConverter.ToInt64(hashText, 0);

            Int64 hashCodeMedium = BitConverter.ToInt64(hashText, 8);

            Int64 hashCodeEnd = BitConverter.ToInt64(hashText, 24);

            hashCode = hashCodeStart ^ hashCodeMedium ^ hashCodeEnd;

        }

        else

        {

            //throw new System.ArgumentException("Parameter cannot be null or empty!");

        }

​

        return hashCode.ToString("X16");

    }

​

    static bool IsHexString(string s)

    {

        foreach (char c in s)

        {

            switch (c)

            {

                case '0':

                case '1':

                case '2':

                case '3':

                case '4':

                case '5':

                case '6':

                case '7':

                case '8':

                case '9':

                case 'a':

                case 'b':

                case 'c':

                case 'd':

                case 'e':

                case 'f':

                case 'A':

                case 'B':

                case 'C':

                case 'D':

                case 'E':

                case 'F':

                    continue;

                default:

                    return false;

            }

        }

        return true;

    }

​

    static string GetHex20(string strText, string prefix)

    {

        if (prefix.Length != 4 || !IsHexString(prefix))

        {

            throw new System.ArgumentException("Prefix '" + prefix + "' must be hex string of length 4.");

        }

​

        return prefix.ToUpper() + GetHex16(strText);

    }

​

    public static void Main()

    {

        Console.WriteLine(GetHex20(" ", "00aa"));

    }

}