Microsoft.Protocols.TestSuites.Common.Common.XOR C# (CSharp) Method

        public static byte[] XOR(byte[] inputStream)
        {
            #region Consts
            // Size of Version field in RPC_HEADER_EXT
            const int RpcHeaderExtVersionByteSize = 2;

            // Size of Flags field in RPC_HEADER_EXT
            const int RpcHeaderExtFlagsByteSize = 2;

            // The length of RPC_HEADER_EXT.
            const int RPCHeaderExtLength = 8;

            // The value that each byte to be obfuscated has XOR applied with, section 3.1.4.11.1.3.
            const byte XorMask = 0xA5;
            #endregion

            if (inputStream == null)
            {
                throw new ArgumentNullException("inputStream");
            }

            if (inputStream.Length < RPCHeaderExtLength)
            {
                throw new ArgumentException("Input must contain valid RPC_HEADER_EXT.", "inputStream");
            }

            ushort size = BitConverter.ToUInt16(inputStream, RpcHeaderExtVersionByteSize + RpcHeaderExtFlagsByteSize);
            byte[] outStream = new byte[size + RPCHeaderExtLength];

            // Copy RPC_HEADER_EXT header info
            Array.Copy(inputStream, 0, outStream, 0, RPCHeaderExtLength);

            // Update XorMagic flag.
            RpcHeaderExtFlags flag = (RpcHeaderExtFlags)BitConverter.ToInt16(inputStream, RpcHeaderExtVersionByteSize);
            flag ^= RpcHeaderExtFlags.XorMagic;
            Array.Copy(BitConverter.GetBytes((short)flag), 0, outStream, RpcHeaderExtVersionByteSize, RpcHeaderExtFlagsByteSize);

            // Obfuscate data by applying XOR to each byte with the value 0xA5
            for (uint counter = RPCHeaderExtLength; counter < outStream.Length; counter++)
            {
                outStream[counter] = (byte)(inputStream[counter] ^ XorMask);
            }

            return outStream;
        }