Generate CSRF token

gistfile1.txt

    /// <summary>
    /// Generates AntiForgery Tokens
    /// </summary>
    public static class AntiForgeryTokensGenerator
    {
        private const string ConstantSalt = "b8YagDpYwB";

        private static readonly RandomNumberGenerator CryptoRandomDataGenerator = new RNGCryptoServiceProvider();

        // buffer for random string with 32 bytes of entropy
        private static readonly int Length = 32;

        /// <summary>
        /// Generates token from seed. If seed is null, random string us used.
        /// </summary>
        /// <param name="seed"></param>
        /// <returns></returns>
        public static string GenerateToken(string seed)
        {
            if (seed == null)
            {
                var buffer = new byte[Length];
                CryptoRandomDataGenerator.GetBytes(buffer);
                seed = Convert.ToBase64String(buffer);
            }
            using (var sha = SHA256.Create())
            {
                var computedHash = sha.ComputeHash(Encoding.Unicode.GetBytes(seed + ConstantSalt));
                var cookieFriendlyHash = Convert.ToBase64String(computedHash);
                return cookieFriendlyHash;
            }
        }
    }