Generate Random Numbers in .NET using RNGCryptoServiceProvider

I have written a couple of posts in the past about generating random numbers in .NET. Generating a random number is as simple as doing the following:

static void Main(string[] args)
{
// code from DevCurry.com
byte[] randomBytes = new byte[4];
Random rando = new Random();
rando.NextBytes(randomBytes);
foreach (byte byteValue in randomBytes)
Console.Write("{0, 4}", byteValue);

Console.ReadLine();
}

The Random class generates pseudo random numbers, based on a seed value. It uses the system clock to generate its seed value. However we were working on a security API and needed an algorithm with a more sophisticated seed value to generate cryptographically secure random numbers. Here’s how we did it using the RNGCryptoServiceProvider class:

static void Main(string[] args)
{
// code from DevCurry.com
byte[] randomBytes = new byte[4];
RNGCryptoServiceProvider rngCrypto =
new RNGCryptoServiceProvider();

rngCrypto.GetBytes(randomBytes);
Int32 rngNum = BitConverter.ToInt32(randomBytes, 0);

Console.WriteLine(rngNum);

Console.ReadLine();
}

The RNGCryptoServiceProvider uses a combination of OS counters, processing info etc. to generate random numbers. Here the GetBytes() fills an array of bytes with a cryptographically strong sequence of random values.

OUTPUT (random)

1187354021

Note: You cannot run a foreach loop here as you did above, since foreach cannot operate on variables of the RNGCryptoServiceProvider as it does not expose GetEnumerator.