Need help with checking passwords!

AuthClient Client = Sender.Wrapper as AuthClient;
            if (Sender.RecvSize == 52)
            {     
                byte[] Recv = param;
                if (BitConverter.ToUInt16(Recv, 2) == 0x41B)
                {
                    byte i = 0;
                    Client.Username = Encoding.ASCII.GetString(Recv, 4, 16).Trim(new char[] { (char)0x0000 });
                    Client.Password = "";
                    while (i < 16)
                    {
                        Client.Password += Recv[i + 16].ToString("X2");
                        i = (byte)(i + 1);
                    }

while (i < 16)
                    {
                        Client.Password += Recv[i + 16].ToString("X2");
                        i = (byte)(i + 1);
                    }

 Client.Password = "";
                    byte[] passarray = new byte[16];
                    Buffer.BlockCopy(Recv, 20, passarray, 0, 16);
                    Client.Password = ConquerPasswordCryptographer.Decrypt(passarray).TrimEnd('\0');
                    Console.WriteLine(Client.Password);

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

namespace ConquerServer_Basic
{
     public sealed class ConquerPasswordCryptographer
     {
          private static uint[] _key = new uint[] {
                                        0xEBE854BC, 0xB04998F7, 0xFFFAA88C, 0x96E854BB, 
                                        0xA9915556, 0x48E44110, 0x9F32308F, 0x27F41D3E, 
                                        0xCF4F3523, 0xEAC3C6B4, 0xE9EA5E03, 0xE5974BBA, 
                                        0x334D7692, 0x2C6BCF2E, 0xDC53B74,  0x995C92A6, 
                                        0x7E4F6D77, 0x1EB2B79F, 0x1D348D89, 0xED641354, 
                                        0x15E04A9D, 0x488DA159, 0x647817D3, 0x8CA0BC20, 
                                        0x9264F7FE, 0x91E78C6C, 0x5C9A07FB, 0xABD4DCCE, 
                                        0x6416F98D, 0x6642AB5B };

          private static uint LeftRotate(uint dwVar, uint dwOffset)
          {
               uint dwTemp1, dwTemp2;

               dwOffset = dwOffset & 0x1F;
               dwTemp1 = dwVar >> (int)(32 - dwOffset);
               dwTemp2 = dwVar << (int)dwOffset;
               dwTemp2 = dwTemp2 | dwTemp1;

               return dwTemp2;
          }

          private static uint RightRotate(uint dwVar, uint dwOffset)
          {
               uint dwTemp1, dwTemp2;

               dwOffset = dwOffset & 0x1F;
               dwTemp1 = dwVar << (int)(32 - dwOffset);
               dwTemp2 = dwVar >> (int)dwOffset;
               dwTemp2 = dwTemp2 | dwTemp1;

               return dwTemp2;
          }

          public static byte[] Encrypt(string password)
          {
               byte[] result = new byte[16];
               Encoding.ASCII.GetBytes(password).CopyTo(result, 0);
               BinaryReader reader = new BinaryReader(new MemoryStream(result, false));
               uint[] passInts = new uint[4];
               for (uint i = 0; i < 4; i++)
                    passInts[i] = (uint)reader.ReadInt32();

               uint temp1, temp2;
               for (int i = 1; i >= 0; i--)
               {
                    temp1 = _key[5] + passInts[(i * 2) + 1];
                    temp2 = _key[4] + passInts[i * 2];
                    for (int j = 0; j < 12; j++)
                    {
                         temp2 = LeftRotate(temp1 ^ temp2, temp1) + _key[j * 2 + 6];
                         temp1 = LeftRotate(temp1 ^ temp2, temp2) + _key[j * 2 + 7];
                    }
                    passInts[i * 2] = temp2;
                    passInts[i * 2 + 1] = temp1;
               }

               BinaryWriter writer = new BinaryWriter(new MemoryStream(result, true));
               for (uint i = 0; i < 4; i++)
                    writer.Write((int)passInts[i]);
               return result;
          }

          public static string Decrypt(byte[] bytes)
          {
               BinaryReader reader = new BinaryReader(new MemoryStream(bytes, false));
               uint[] passInts = new uint[4];
               for (uint i = 0; i < 4; i++)
                    passInts[i] = (uint)reader.ReadInt32();

               uint temp1, temp2;
               for (int i = 1; i >= 0; i--)
               {
                    temp1 = passInts[(i * 2) + 1];
                    temp2 = passInts[i * 2];
                    for (int j = 11; j >= 0; j--)
                    {
                         temp1 = RightRotate(temp1 - _key[j * 2 + 7], temp2) ^ temp2;
                         temp2 = RightRotate(temp2 - _key[j * 2 + 6], temp1) ^ temp1;
                    }
                    passInts[i * 2 + 1] = temp1 - _key[5];
                    passInts[i * 2] = temp2 - _key[4];
               }

               BinaryWriter writer = new BinaryWriter(new MemoryStream(bytes, true));
               for (uint i = 0; i < 4; i++)
                    writer.Write((int)passInts[i]);
               for (int i = 0; i < 16; i++)
                    if (bytes[i] == 0)
                         return Encoding.ASCII.GetString(bytes, 0, i);
               return Encoding.ASCII.GetString(bytes);
          }
     }
}

public class SHA2
    {
        public static string sha256encrypt(string phrase)
        {
            UTF8Encoding encoder = new UTF8Encoding();
            SHA256Managed sha256hasher = new SHA256Managed();
            byte[] hashedDataBytes = sha256hasher.ComputeHash(encoder.GetBytes(phrase));
            return byteArrayToString(hashedDataBytes);
        }

        private static string byteArrayToString(byte[] inputArray)
        {
            StringBuilder output = new StringBuilder("");
            for (int i = 0; i < inputArray.Length; i++)
            {
                output.Append(inputArray[i].ToString("X2"));
            }
            return output.ToString();
        }
    }