private AuthResponse AuthStep1(AuthRequest authRequest)
        {
            // first step never fails: User -> Host: I, A = g^a (identifies self, a = random number)
            var userName = authRequest.GetUserName();
            var clientEphemeralPublic = authRequest.GetClientPublicEphemeral();
            var account = AuthRepository.FindByName(userName);

            if (account != null)
            {
                // save the data for the second authentication step
                var salt            = account.Salt;
                var verifier        = account.Verifier;
                var serverEphemeral = SrpServer.GenerateEphemeral(verifier);
                PendingAuthentications[authRequest.GetLoginSession()] = new Step1Data
                {
                    Account = account,
                    ClientEphemeralPublic = clientEphemeralPublic,
                    ServerEphemeral       = serverEphemeral,
                };

                // Host -> User: s, B = kv + g^b (sends salt, b = random number)
                return(ResponseStep1(salt, serverEphemeral.Public, authRequest.GetLoginSession()));
            }

            var fakeSalt      = SrpParameters.Hash(userName + UnknownUserSalt).ToHex();
            var fakeEphemeral = SrpServer.GenerateEphemeral(fakeSalt);

            return(ResponseStep1(fakeSalt, fakeEphemeral.Public, authRequest.GetLoginSession()));
        }