System.Net.Security.NegotiateStream.AuthenticateAsClient C# (CSharp) Method

        public virtual void AuthenticateAsClient()
        {
            AuthenticateAsClient((NetworkCredential)CredentialCache.DefaultCredentials, null, string.Empty, ProtectionLevel.EncryptAndSign, TokenImpersonationLevel.Identification);
        }

        /// <summary>
        /// Authenticates the client using the supplied stream.
        /// </summary>
        /// <param name="stream">the stream to use to authenticate the connection.</param>
        /// <param name="additionalChallenge">Additional data that much match between the client and server
        /// for the connection to succeed.</param>
        /// <returns>
        /// True if authentication succeded, false otherwise.
        /// </returns>
        public bool TryAuthenticateAsClient(Stream stream, byte[] additionalChallenge = null)
        {
            if (additionalChallenge == null)
                additionalChallenge = new byte[] { };
            if (additionalChallenge.Length > short.MaxValue)
                throw new ArgumentOutOfRangeException("additionalChallenge","Must be less than 32767 bytes");

            using (var negotiateStream = new NegotiateStream(stream, true))
            {
                try
                {
                    negotiateStream.AuthenticateAsClient(m_credentials, string.Empty, ProtectionLevel.EncryptAndSign, TokenImpersonationLevel.Identification);
                }
                catch (Exception ex)
                {
                    Log.Publish(MessageLevel.Info, "Security Login Failed", "Attempting an integrated security login failed", null, ex);
                    return false;
                }

                //Exchange the challenge data.
                //Since NegotiateStream is already a trusted stream
                //Simply writing the raw is as secure as creating a challenge response
                negotiateStream.Write((short)additionalChallenge.Length);
                if (additionalChallenge.Length > 0)
                {
                    negotiateStream.Write(additionalChallenge);
                }
                negotiateStream.Flush();

                int len = negotiateStream.ReadInt16();
                if (len < 0)
                {
                    Log.Publish(MessageLevel.Info, "Security Login Failed", "Attempting an integrated security login failed", "Challenge Length is invalid: " + len.ToString());
                    return false;
                }

                byte[] remoteChallenge;
                if (len == 0)
                {
                    remoteChallenge = new byte[0];
                }
                else
                {
                    remoteChallenge = negotiateStream.ReadBytes(len);
                }

                if (remoteChallenge.SecureEquals(additionalChallenge))
                {
                    return true;
                }
                else
                {
                    Log.Publish(MessageLevel.Info, "Security Login Failed", "Attempting an integrated security login failed", "Challenge did not match. Potential man in the middle attack.");
                    return false;
                }
            }
        }