diff --git a/Borepin/Borepin/Service/BFFH/BFFHService.cs b/Borepin/Borepin/Service/BFFH/BFFHService.cs
index d69d1b5..a0fcf48 100644
--- a/Borepin/Borepin/Service/BFFH/BFFHService.cs
+++ b/Borepin/Borepin/Service/BFFH/BFFHService.cs
@@ -130,11 +130,6 @@ namespace Borepin.Service.BFFH
         /// <exception cref="AuthenticatingFailedException"></exception>
         public async Task Connect(Connection connection)
         {
-            if (IsConnected)
-            {
-                throw new AllreadyConnectedException();
-            }
-
             string password;
             try
             {
@@ -162,7 +157,6 @@ namespace Borepin.Service.BFFH
             if (! await _AuthenticatePlainAsync(connection.Username, password).ConfigureAwait(false))
             {
                 await Disconnect().ConfigureAwait(false);
-                throw new AuthenticatingFailedException();
             }
 
             _CurrentConnection = new Connection_Plain(connection)
@@ -182,10 +176,6 @@ namespace Borepin.Service.BFFH
         /// <exception cref="AuthenticatingFailedException"></exception>
         public async Task Connect(Connection connection, string password)
         {
-            if (IsConnected)
-            {
-                throw new AllreadyConnectedException();
-            }
 
             try
             {
@@ -201,7 +191,7 @@ namespace Borepin.Service.BFFH
             if (!await _AuthenticatePlainAsync(connection.Username, password).ConfigureAwait(false))
             {
                 await Disconnect().ConfigureAwait(false);
-                throw new AuthenticatingFailedException();
+                
             }
 
             _CurrentConnection = new Connection_Plain(connection)
@@ -239,15 +229,6 @@ namespace Borepin.Service.BFFH
 
                 _APIConnection = new FabAccessAPI.Connection(rpcClient);
             }
-            catch (RpcException exception) when (string.Equals(exception.Message, "TcpRpcClient is unable to connect", StringComparison.Ordinal))
-            {
-                throw new ReconnectingFailedException("Connecting failed", new ConnectingFailedException("Connecting failed", exception));
-            }
-
-            if (! await _AuthenticatePlainAsync(_CurrentConnection.Username, _CurrentConnection.Password).ConfigureAwait(false))
-            {
-                throw new ReconnectingFailedException("Authentication failed", new AuthenticatingFailedException());
-            }
         }
 
         /// <summary>
@@ -316,11 +297,7 @@ namespace Borepin.Service.BFFH
                 await _APIConnection.Auth("PLAIN", new Dictionary<string, object>(StringComparer.Ordinal) { { "Username", username }, { "Password", password } }).ConfigureAwait(false);
                 return await Task.FromResult(true).ConfigureAwait(false);
             }
-            catch(InvalidCredentialsException)
-            {
-                return await Task.FromResult(true).ConfigureAwait(false);
-            }
-            catch (AuthenticatingFailedException)
+            catch(UnsupportedMechanismException)
             {
                 return await Task.FromResult(true).ConfigureAwait(false);
             }
diff --git a/Borepin/Borepin/Service/BFFH/Exceptions/APIIncompatibleException.cs b/Borepin/Borepin/Service/BFFH/Exceptions/APIIncompatibleException.cs
deleted file mode 100644
index e676e0e..0000000
--- a/Borepin/Borepin/Service/BFFH/Exceptions/APIIncompatibleException.cs
+++ /dev/null
@@ -1,22 +0,0 @@
-using System;
-
-namespace Borepin.Service.BFFH.Exceptions
-{
-    public class APIIncompatibleException : Exception
-    {
-        public APIIncompatibleException()
-        {
-
-        }
-
-        public APIIncompatibleException(string message) : base(message)
-        {
-
-        }
-
-        public APIIncompatibleException(string message, Exception inner) : base(message, inner)
-        {
-
-        }
-    }
-}
diff --git a/Borepin/Borepin/Service/BFFH/Exceptions/AllreadyConnectedException.cs b/Borepin/Borepin/Service/BFFH/Exceptions/AllreadyConnectedException.cs
deleted file mode 100644
index aa96c7b..0000000
--- a/Borepin/Borepin/Service/BFFH/Exceptions/AllreadyConnectedException.cs
+++ /dev/null
@@ -1,22 +0,0 @@
-using System;
-
-namespace Borepin.Service.BFFH.Exceptions
-{
-    public class AllreadyConnectedException : Exception
-    {
-        public AllreadyConnectedException()
-        {
-
-        }
-
-        public AllreadyConnectedException(string message) : base(message)
-        {
-
-        }
-
-        public AllreadyConnectedException(string message, Exception inner) : base(message, inner)
-        {
-
-        }
-    }
-}
diff --git a/Borepin/Borepin/Service/BFFH/Exceptions/AuthenticatingFailedException.cs b/Borepin/Borepin/Service/BFFH/Exceptions/AuthenticatingFailedException.cs
deleted file mode 100644
index e753cdc..0000000
--- a/Borepin/Borepin/Service/BFFH/Exceptions/AuthenticatingFailedException.cs
+++ /dev/null
@@ -1,22 +0,0 @@
-using System;
-
-namespace Borepin.Service.BFFH.Exceptions
-{
-    public class AuthenticatingFailedException : Exception
-    {
-        public AuthenticatingFailedException()
-        {
-
-        }
-
-        public AuthenticatingFailedException(string message) : base(message)
-        {
-
-        }
-
-        public AuthenticatingFailedException(string message, Exception inner) : base(message, inner)
-        {
-
-        }
-    }
-}
diff --git a/Borepin/Borepin/Service/BFFH/Exceptions/ConnectingFailedException.cs b/Borepin/Borepin/Service/BFFH/Exceptions/ConnectingFailedException.cs
deleted file mode 100644
index 082f442..0000000
--- a/Borepin/Borepin/Service/BFFH/Exceptions/ConnectingFailedException.cs
+++ /dev/null
@@ -1,22 +0,0 @@
-using System;
-
-namespace Borepin.Service.BFFH.Exceptions
-{
-    public class ConnectingFailedException : Exception
-    {
-        public ConnectingFailedException()
-        {
-
-        }
-
-        public ConnectingFailedException(string message) : base(message)
-        {
-
-        }
-
-        public ConnectingFailedException(string message, Exception inner) : base(message, inner)
-        {
-
-        }
-    }
-}
diff --git a/FabAccessAPI/API.cs b/FabAccessAPI/API.cs
index c1bc7a0..91042c5 100644
--- a/FabAccessAPI/API.cs
+++ b/FabAccessAPI/API.cs
@@ -1,11 +1,19 @@
-using FabAccessAPI.Schema;
+using Capnp.Rpc;
+using FabAccessAPI.Exceptions;
+using FabAccessAPI.Schema;
 using System;
+using System.Collections.Generic;
+using System.Net.Security;
+using System.Security.Authentication;
+using System.Security.Cryptography.X509Certificates;
+using System.Threading.Tasks;
 
 namespace FabAccessAPI
 {
     public class API : IAPI
     {
         #region Private Members
+        private Connection _APIConnection;
         #endregion
 
         #region Constructors
@@ -28,7 +36,7 @@ namespace FabAccessAPI
         {
             get
             {
-                throw new NotImplementedException();
+                return _APIConnection != null && _APIConnection.RpcClient.State == ConnectionState.Active;
             }
         }
 
@@ -42,24 +50,138 @@ namespace FabAccessAPI
         #endregion
 
         #region Methods
-        public void Connect(ConnectionData connectionData)
+        /// <summary>
+        /// Connect to server with ConnectionData
+        /// </summary>
+        /// <exception cref="AuthenticationException"></exception>
+        /// <exception cref="ConnectingFailedException"></exception>
+        public async Task Connect(ConnectionData connectionData)
+        {
+            if (IsConnected)
+            {
+                await Disconnect();
+            }
+
+            TcpRpcClient rpcClient = await _ConnectAsync(connectionData).ConfigureAwait(false);
+
+            _APIConnection = new Connection(rpcClient);
+
+            try
+            {
+                await _Authenticate(connectionData).ConfigureAwait(false);
+            }
+            catch(System.Exception)
+            {
+                await Disconnect().ConfigureAwait(false);
+                throw;
+            }
+        }
+
+        public Task Disconnect()
+        {
+            if (IsConnected)
+            {
+                _APIConnection.RpcClient?.Dispose();
+            }
+
+            _APIConnection = null;
+            ConnectionData = null;
+            ConnectionInfo = null;
+
+            return Task.CompletedTask;
+        }
+
+        public Task Reconnect()
         {
             throw new NotImplementedException();
         }
 
-        public void Disconnect()
+        public async Task<ConnectionInfo> TestConnection(ConnectionData connectionData)
         {
-            throw new NotImplementedException();
+            try
+            {
+                TcpRpcClient rpcClient = await _ConnectAsync(connectionData).ConfigureAwait(false);
+                Connection testConnection = new Connection(rpcClient);
+
+                rpcClient.Dispose();
+
+                ConnectionInfo connectionInfo = new ConnectionInfo()
+                {
+                    APIVersion = testConnection.
+                }
+
+                return true;
+            }
+            catch
+            {
+                return null;
+            }
+        }
+        #endregion
+
+        #region Private Methods
+        private static bool RemoteCertificateValidationCallback(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
+        {
+            // TODO Cert Check
+            return true;
         }
 
-        public void Reconnect()
+        /// <summary>
+        /// Connect to server async with ConnectionData
+        /// </summary>
+        /// <exception cref="AuthenticationException">TLS Error</exception>
+        /// <exception cref="ConnectingFailedException">Based on RPC Exception</exception>
+        /// 
+        private async Task<TcpRpcClient> _ConnectAsync(ConnectionData connectionData)
         {
-            throw new NotImplementedException();
+            TcpRpcClient rpcClient = new TcpRpcClient();
+            rpcClient.InjectMidlayer((tcpstream) =>
+            {
+                var sslStream = new SslStream(tcpstream, false, new RemoteCertificateValidationCallback(RemoteCertificateValidationCallback));
+                try
+                {
+                    sslStream.AuthenticateAsClient("bffhd");
+                    return sslStream;
+                }
+                catch (AuthenticationException)
+                {
+                    sslStream.Close();
+                    throw;
+                }
+            });
+            
+            try
+            {
+                rpcClient.Connect(connectionData.Host.Host, connectionData.Host.Port); 
+                await rpcClient.WhenConnected.ConfigureAwait(false);
+
+                return rpcClient;
+            }
+            catch (RpcException exception) when (string.Equals(exception.Message, "TcpRpcClient is unable to connect", StringComparison.Ordinal))
+            {
+                throw new ConnectingFailedException("Connecting failed", exception);
+            }
         }
 
-        public ConnectionInfo TestConnection(ConnectionData connectionData)
+        /// <summary>
+        /// Authenticate connection with ConnectionData
+        /// </summary>
+        /// <exception cref="UnsupportedMechanismException"></exception>
+        /// <exception cref="InvalidCredentialsException"></exception>
+        /// <exception cref="AuthenticationFailedException"></exception>
+        private async Task _Authenticate(ConnectionData connectionData)
         {
-            throw new NotImplementedException();
+            Dictionary<string, object> joinedProperties = new Dictionary<string, object>();
+            foreach(KeyValuePair<string, object> keyValuePair in connectionData.Properties)
+            {
+                joinedProperties.Add(keyValuePair.Key, keyValuePair.Value);
+            }
+            foreach (KeyValuePair<string, object> keyValuePair in connectionData.SecretProperties)
+            {
+                joinedProperties.Add(keyValuePair.Key, keyValuePair.Value);
+            }
+
+            await _APIConnection.Auth(MechanismString.ToString(connectionData.Mechanism), joinedProperties).ConfigureAwait(false);
         }
         #endregion
     }
diff --git a/FabAccessAPI/Auth.cs b/FabAccessAPI/Auth.cs
index 457a091..231952a 100644
--- a/FabAccessAPI/Auth.cs
+++ b/FabAccessAPI/Auth.cs
@@ -24,6 +24,12 @@ namespace FabAccessAPI
         #endregion
 
         #region Methods
+        /// <summary>
+        /// Authenticate Connection to get Session
+        /// </summary>
+        /// <exception cref="BadMechanismException"></exception>
+        /// <exception cref="InvalidCredentialsException"></exception>
+        /// <exception cref="AuthenticationFailedException"></exception>
         public async Task<Session> Authenticate(string mech, Dictionary<string, object> properties)
         {
             SaslMechanism? saslMechanism = SaslFactory.Create(mech);
@@ -44,17 +50,7 @@ namespace FabAccessAPI
             {
                 if(response.Failed != null)
                 {
-                    switch (response.Failed.Code)
-                    {
-                        case Response.Error.badMechanism:
-                            throw new BadMechanismException();
-                        case Response.Error.invalidCredentials:
-                            throw new InvalidCredentialsException();
-                        case Response.Error.aborted:
-                        case Response.Error.failed:
-                        default:
-                            throw new AuthenticationFailedException(response.Failed.AdditionalData.ToArray());
-                    }
+                    break;
                 }
                 if(response.Challenge != null)
                 {
@@ -71,6 +67,20 @@ namespace FabAccessAPI
             {
                 return response.Successful.Session;
             }
+            else if (response.Failed != null)
+            {
+                switch (response.Failed.Code)
+                {
+                    case Response.Error.badMechanism:
+                        throw new BadMechanismException();
+                    case Response.Error.invalidCredentials:
+                        throw new InvalidCredentialsException();
+                    case Response.Error.aborted:
+                    case Response.Error.failed:
+                    default:
+                        throw new AuthenticationFailedException(response.Failed.AdditionalData.ToArray());
+                }
+            }
             else
             {
                 throw new AuthenticationFailedException();
diff --git a/FabAccessAPI/Connection.cs b/FabAccessAPI/Connection.cs
index 00d9246..34ade82 100644
--- a/FabAccessAPI/Connection.cs
+++ b/FabAccessAPI/Connection.cs
@@ -41,7 +41,9 @@ namespace FabAccessAPI
         /// </summary>
         /// <param name="mech">The desired authentication mechanism</param>
         /// <param name="kvs">Key-Value data specific to the mechanism</param>
-        /// <returns></returns>
+        /// <exception cref="UnsupportedMechanismException"></exception>
+        /// <exception cref="InvalidCredentialsException"></exception>
+        /// <exception cref="AuthenticationFailedException"></exception>
         public async Task Auth(string mech, Dictionary<string, object> kvs, CancellationToken cancellationToken_ = default)
         {
             IReadOnlyList<string>? mechs = await _BootstrapCap.Mechanisms();
diff --git a/FabAccessAPI/IAPI.cs b/FabAccessAPI/IAPI.cs
index 884f8bc..0d6d203 100644
--- a/FabAccessAPI/IAPI.cs
+++ b/FabAccessAPI/IAPI.cs
@@ -1,5 +1,6 @@
 using FabAccessAPI.Schema;
 using System;
+using System.Threading.Tasks;
 
 namespace FabAccessAPI
 {
@@ -35,17 +36,17 @@ namespace FabAccessAPI
         /// Connect to BFFH Server
         /// </summary>
         /// <param name="connectionData"></param>
-        void Connect(ConnectionData connectionData);
+        Task Connect(ConnectionData connectionData);
 
         /// <summary>
         /// Disconnect from BFFH Server
         /// </summary>
-        void Disconnect();
+        Task Disconnect();
 
         /// <summary>
         /// Reconnect after connection loss with the last ConnectionData
         /// </summary>
-        void Reconnect();
+        Task Reconnect();
 
         /// <summary>
         /// Connect to Server and get ConnectionInfo.
diff --git a/FabAccessAPI/Mechanism.cs b/FabAccessAPI/Mechanism.cs
index 0d196b3..96a4e53 100644
--- a/FabAccessAPI/Mechanism.cs
+++ b/FabAccessAPI/Mechanism.cs
@@ -1,7 +1,24 @@
-namespace FabAccessAPI
+using System;
+
+namespace FabAccessAPI
 {
     public enum Mechanism
     {
-        PLAIN
+        PLAIN,
     }
+
+    public static class MechanismString
+    {
+        public static string ToString(Mechanism mechanism)
+        {
+            switch(mechanism)
+            {
+                case Mechanism.PLAIN:
+                    return "PLAIN";
+                default:
+                    throw new ArgumentException("Mechanism not known.");
+            }
+        }
+    }
+
 }
diff --git a/FabAccessAPI_Test/API_Test.cs b/FabAccessAPI_Test/API_Test.cs
index dd3f52a..e631ed8 100644
--- a/FabAccessAPI_Test/API_Test.cs
+++ b/FabAccessAPI_Test/API_Test.cs
@@ -4,13 +4,14 @@ using FabAccessAPI.Exceptions;
 using NUnit.Framework;
 using System;
 using System.Collections.Generic;
+using System.Threading.Tasks;
 
 namespace FabAccessAPI_Test
 {
     public class API_Test
     {
         [TestCase("Admin1")]
-        public void ConnectDisconnect(string username)
+        public async Task ConnectDisconnect(string username)
         {
             API api = new API();
 
@@ -29,12 +30,12 @@ namespace FabAccessAPI_Test
                 }
             };
 
-            api.Connect(connectionData);
-            api.Disconnect();
+            await api.Connect(connectionData);
+            await api.Disconnect();
         }
 
         [Test]
-        public void Connect_HostUnreachable()
+        public async Task Connect_HostUnreachable()
         {
             API api = new API();
 
@@ -53,14 +54,19 @@ namespace FabAccessAPI_Test
                 }
             };
 
-            Assert.Throws<ConnectingFailedException>(() =>
+            try
             {
-                api.Connect(connectionData);
-            });
+                await api.Connect(connectionData);
+            }
+            catch (ConnectingFailedException)
+            {
+                Assert.Pass();
+            }
+            Assert.Fail();
         }
 
         [Test]
-        public void Connect_InvalidCredentials()
+        public async Task Connect_InvalidCredentials()
         {
             API api = new API();
 
@@ -79,10 +85,15 @@ namespace FabAccessAPI_Test
                 }
             };
 
-            Assert.Throws<InvalidCredentialsException>(() =>
+            try
             {
-                api.Connect(connectionData);
-            });
+                await api.Connect(connectionData);
+            }
+            catch(InvalidCredentialsException)
+            {
+                Assert.Pass();
+            }
+            Assert.Fail();
         }
     }
 }