using System;

public class Program

{  

         public static byte[] buf, m;

         public static ulong messageLength, blocksQty;

        public static void hash(byte[] message) 

        { //operates only with byte-multiple messages 

            buf = new byte[message.LongLength];

            Array.Copy(message, buf, message.LongLength);

            messageLength = (ulong)message.LongLength;

            completeMessageLength();

            blocksQty = (ulong)m.LongLength / 64;

        }

​

        public static void completeMessageLength()

        {

            int zeroBitsToAddQty = 512 - (int)(((ulong)buf.LongLength * 8 + 1 + 64) % 512);

            m = new byte[((ulong)buf.LongLength * 8 + 1 + 64 + (ulong)zeroBitsToAddQty) / 8];

            Array.Copy(buf, m, buf.LongLength);

​

            m[buf.LongLength] = 128; //set 1-st bit to "1", 7 remaining to "0" (may not work with bit-multiple message!!)

            for (ulong i = (messageLength + 1); i < (ulong)m.LongLength; i++)

            {

                m[i] = 0;

            }

​

            byte[] messageBitLength_little_endian = BitConverter.GetBytes(messageLength * 8);

            byte[] messageBitLength_big_endian = new byte[messageBitLength_little_endian.Length];

            for (int i = 0, j = messageBitLength_little_endian.Length - 1; i < messageBitLength_little_endian.Length; i++, j--)

            {

                messageBitLength_big_endian[i] = messageBitLength_little_endian[j];

            }

            Array.Copy(messageBitLength_big_endian, 0, m, m.LongLength - 8, 8);

​

        }

​

    public static void Main()

    {

        System.Text.Encoding enc = System.Text.Encoding.GetEncoding("KOI8");

        byte[] _buf  = enc.GetBytes("abc");

        Console.WriteLine(enc.GetString(_buf));

        hash(_buf);

        Console.WriteLine("Hello World");

    }

}