util.cs

gerador.cs

public static string GerarStringAleatoria(int length)
        {
            const string valid = "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
            StringBuilder res = new StringBuilder();
            var cryptoResult = new byte[4];
            new System.Security.Cryptography.RNGCryptoServiceProvider().GetBytes(cryptoResult);

            int seed = BitConverter.ToInt32(cryptoResult, 0);

            Random rnd = new Random(seed);

            while (0 < length--)
                res.Append(valid[rnd.Next(valid.Length)]);

            return res.ToString();
        }