Generate random string

RandomString.cs

public static class StringExtensions
{
	// Generates a random seq of characters
	// e.g. "bcdfghjklmnpqrstvwxyzBCDFGHJKLMNPQRSTVWXYZ01234567890!@#$%&*()-+".Randomize(8);
	public static string Randomize(this string characters, int len)
	{
		var rng = new RNGCryptoServiceProvider();
		var builder = new StringBuilder(len);
		var bytes = new byte[4];
		for (var i = 0; i < len; i++)
		{
			rng.GetBytes(bytes);
			var idx = Math.Abs(BitConverter.ToInt32(bytes, 0)) % characters.Length;
			builder.Append(characters[idx]);
		}
		return builder.ToString();
	}
}