C# sample code for using with Windows Entropy Server through a named pipe connection

using System;
using System.IO;
using System.IO.Pipes;

//
// A sample C# code that demonstrates how to use entropy server to download random bytes from SwiftRNG device.
// Before running this sample, make sure the entropy server is running on local computer. 
//
namespace SwiftRNGEntropyClient
{
    class Program
    {
        static void Main(string[] args)
        {

            NamedPipeClientStream client = new NamedPipeClientStream("SwiftRNG");
            client.Connect();
            BinaryReader reader = new BinaryReader(client);
            BinaryWriter writer = new BinaryWriter(client);

            // Prepare storage for 16 random bytes
            byte[] rndBytes = new byte[16];

            // Send a request to the entropy server to generate 16 bytes
            sendRequest(writer, rndBytes.Length);
            
            // Download 16 random bytes from the entropy server
            receiveResponse(reader, rndBytes);

            // Display downloaded random bytes
            foreach (byte b in rndBytes)
            {
                Console.WriteLine(b);
            }

            writer.Close();
            reader.Close();
            client.Close();
        }

        /// <summary>
        /// Read generated random bytes from the entropy server
        /// </summary>
        /// <param name="reader"></param>
        /// <param name="rndBytes"></param>
        static void receiveResponse(BinaryReader reader, byte[] rndBytes)
        {
            // Read random bytes from entropy server.
            // Random bytes should be received at once with no delay in between.
            int actualBytesReceived = reader.Read(rndBytes, 0, rndBytes.Length);
            if (actualBytesReceived != rndBytes.Length)
            {
                throw new Exception("Error when downloading random bytes");
            }
        }

        /// <summary>
        /// Send the request to the entropy server. The request size is always 8 bytes.
        /// </summary>
        /// <param name="writer"></param>
        /// <param name="byteCount"></param>
        static void sendRequest(BinaryWriter writer, int byteCount)
        {
            if (byteCount < 1 || byteCount > 100000)
            {
                throw new Exception("Invalid request, must be between 1 and 100000 bytes");
            }
            // Prepare the command header
            byte[] requestBytes = new byte[8];

            // Set the byte count in the header
            byte[] byteCountBytes = BitConverter.GetBytes(byteCount);
            for (int i = 4; i < requestBytes.Length; i++)
            {
                requestBytes[i] = byteCountBytes[i - 4];
            }
            // Request bytes should be sent at once with no delay in between.
            writer.Write(requestBytes);
            writer.Flush();
        }
    }
}