Added SFTP support to the current master branch code. Needs testing.

AutoUpdater.NET/AutoUpdater.NET.csproj

@@ -14,7 +14,7 @@
         <Version>1.7.7.0</Version>
         <AssemblyVersion>1.7.7.0</AssemblyVersion>
         <FileVersion>1.7.7.0</FileVersion>
-        <SignAssembly>true</SignAssembly>
+        <SignAssembly>False</SignAssembly>
         <AssemblyOriginatorKeyFile>AutoUpdater.NET.snk</AssemblyOriginatorKeyFile>
         <NeutralLanguage>en</NeutralLanguage>
         <PackageId>Autoupdater.NET.Official</PackageId>
@@ -51,6 +51,11 @@
         <PackageReference Include="Resource.Embedder" Version="1.2.8" PrivateAssets="All" />
     </ItemGroup>
     <ItemGroup>
+        <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.3">
+          <PrivateAssets>all</PrivateAssets>
+          <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+        </PackageReference>
         <PackageReference Include="Microsoft.Web.WebView2" Version="1.0.1587.40" />
+        <PackageReference Include="SSH.NET" Version="2020.0.2" />
     </ItemGroup>
 </Project>

AutoUpdater.NET/AutoUpdater.cs

@@ -151,6 +151,12 @@ public static class AutoUpdater
         /// </summary>
         public static bool ReportErrors = false;
 
+        ///<summary>
+        ///     AutoUpdater.NET will not show the 'No Update Available' dialog if 
+        ///     no update is available and this is true.
+        /// </summary>
+        public static bool SilentOnNoUpdate = false;
+
         /// <summary>
         ///     Set this to false if your application doesn't need administrator privileges to replace the old version.
         /// </summary>
@@ -258,8 +264,8 @@ public static void Start(string appCast, Assembly myAssembly = null)
         {
             try
             {
-                ServicePointManager.SecurityProtocol |= (SecurityProtocolType) 192 |
-                                                        (SecurityProtocolType) 768 | (SecurityProtocolType) 3072;
+                ServicePointManager.SecurityProtocol |= (SecurityProtocolType)192 |
+                                                        (SecurityProtocolType)768 | (SecurityProtocolType)3072;
             }
             catch (NotSupportedException)
             {
@@ -331,9 +337,9 @@ public static void Start(string appCast, Assembly myAssembly = null)
                                         return;
                                     }
                                 }
-
-                                Running = false;
                             }
+
+                            Running = false;
                         };
 
                         backgroundWorker.RunWorkerAsync(assembly);
@@ -345,13 +351,13 @@ public static void Start(string appCast, Assembly myAssembly = null)
         private static object CheckUpdate(Assembly mainAssembly)
         {
             var companyAttribute =
-                (AssemblyCompanyAttribute) GetAttribute(mainAssembly, typeof(AssemblyCompanyAttribute));
+            (AssemblyCompanyAttribute)GetAttribute(mainAssembly, typeof(AssemblyCompanyAttribute));
             string appCompany = companyAttribute != null ? companyAttribute.Company : "";
 
             if (string.IsNullOrEmpty(AppTitle))
             {
                 var titleAttribute =
-                    (AssemblyTitleAttribute) GetAttribute(mainAssembly, typeof(AssemblyTitleAttribute));
+                    (AssemblyTitleAttribute)GetAttribute(mainAssembly, typeof(AssemblyTitleAttribute));
                 AppTitle = titleAttribute != null ? titleAttribute.Title : mainAssembly.GetName().Name;
             }
 
@@ -362,32 +368,40 @@ private static object CheckUpdate(Assembly mainAssembly)
             PersistenceProvider ??= new RegistryPersistenceProvider(registryLocation);
 
             BaseUri = new Uri(AppCastURL);
+            string xml = string.Empty;
+
+            switch (BaseUri.Scheme.ToLower())
+            {
+                case "sftp":
+                    xml = GetUpdateXmlBySSHClient();
+                    break;
+
+                default:
+                    xml = GetUpdateXmlByWebClient();
+                    break;
+            }
 
             UpdateInfoEventArgs args;
-            using (MyWebClient client = GetWebClient(BaseUri, BasicAuthXML))
+
+            if (ParseUpdateInfoEvent == null)
             {
-                string xml = client.DownloadString(BaseUri);
-
-                if (ParseUpdateInfoEvent == null)
-                {
-                    XmlSerializer xmlSerializer = new XmlSerializer(typeof(UpdateInfoEventArgs));
-                    XmlTextReader xmlTextReader = new XmlTextReader(new StringReader(xml)) {XmlResolver = null};
-                    args = (UpdateInfoEventArgs) xmlSerializer.Deserialize(xmlTextReader);
-                }
-                else
-                {
-                    ParseUpdateInfoEventArgs parseArgs = new ParseUpdateInfoEventArgs(xml);
-                    ParseUpdateInfoEvent(parseArgs);
-                    args = parseArgs.UpdateInfo;
-                }
+                XmlSerializer xmlSerializer = new XmlSerializer(typeof(UpdateInfoEventArgs));
+                XmlTextReader xmlTextReader = new XmlTextReader(new StringReader(xml)) { XmlResolver = null };
+                args = (UpdateInfoEventArgs)xmlSerializer.Deserialize(xmlTextReader);
+            }
+            else
+            {
+                ParseUpdateInfoEventArgs parseArgs = new ParseUpdateInfoEventArgs(xml);
+                ParseUpdateInfoEvent(parseArgs);
+                args = parseArgs.UpdateInfo;
             }
 
             if (string.IsNullOrEmpty(args?.CurrentVersion) || string.IsNullOrEmpty(args.DownloadURL))
             {
                 throw new MissingFieldException();
             }
 
-            args.InstalledVersion = InstalledVersion ?? mainAssembly.GetName().Version;
+            args.InstalledVersion = InstalledVersion != null ? InstalledVersion : mainAssembly.GetName().Version;
             args.IsUpdateAvailable = new Version(args.CurrentVersion) > args.InstalledVersion;
 
             if (!Mandatory)
@@ -434,10 +448,34 @@ private static object CheckUpdate(Assembly mainAssembly)
                     }
                 }
             }
-
             return args;
         }
 
+        private static string GetUpdateXmlBySSHClient()
+        {
+            string xml = string.Empty;
+            string host = BaseUri.Host;
+
+            MySSHClient client = new MySSHClient(
+                host: host, userName: FtpCredentials.UserName,
+                password: FtpCredentials.Password);
+
+            xml = client.GetFileContentAsString(BaseUri.AbsolutePath);
+
+            return xml;
+        }
+
+        private static string GetUpdateXmlByWebClient()
+        {
+            string xml = string.Empty;
+
+            using (MyWebClient client = GetWebClient(BaseUri, BasicAuthXML))
+            {
+                xml = client.DownloadString(BaseUri);
+            }
+
+            return xml;
+        }
         private static bool StartUpdate(object result)
         {
             if (result is DateTime time)
@@ -481,7 +519,7 @@ private static bool StartUpdate(object result)
                             return true;
                         }
 
-                        if (ReportErrors)
+                        if (ReportErrors && !SilentOnNoUpdate)
                         {
                             MessageBox.Show(Resources.UpdateUnavailableMessage,
                                 Resources.UpdateUnavailableCaption,
@@ -498,7 +536,7 @@ private static void ShowError(Exception exception)
         {
             if (CheckForUpdateEvent != null)
             {
-                CheckForUpdateEvent(new UpdateInfoEventArgs {Error = exception});
+                CheckForUpdateEvent(new UpdateInfoEventArgs { Error = exception });
             }
             else
             {
@@ -518,8 +556,6 @@ private static void ShowError(Exception exception)
                     }
                 }
             }
-
-            Running = false;
         }
 
         /// <summary>
@@ -547,7 +583,7 @@ internal static void Exit()
                 {
                     if (process.CloseMainWindow())
                     {
-                        process.WaitForExit((int) TimeSpan.FromSeconds(10)
+                        process.WaitForExit((int)TimeSpan.FromSeconds(10)
                             .TotalMilliseconds); //give some time to process message
                     }
 
@@ -589,7 +625,7 @@ private static Attribute GetAttribute(Assembly assembly, Type attributeType)
                 return null;
             }
 
-            return (Attribute) attributes[0];
+            return (Attribute)attributes[0];
         }
 
         internal static string GetUserAgent()
@@ -695,5 +731,15 @@ internal static MyWebClient GetWebClient(Uri uri, IAuthentication basicAuthentic
 
             return webClient;
         }
+
+        internal static MySSHClient GetSSHClient(Uri uri, IAuthentication basicAuthentication)
+        {
+            MySSHClient sshClient = new MySSHClient(
+                host: uri.Host,
+                userName: FtpCredentials.UserName,
+                password: FtpCredentials.Password);
+
+            return sshClient;
+        }
     }
 }

AutoUpdater.NET/DownloadProgressChangedEventArgs.cs

@@ -0,0 +1,34 @@
+using System.ComponentModel;
+
+namespace AutoUpdaterDotNET
+{
+    //
+    // Summary:
+    //     Provides data for the SSH client DownloadProgressChanged event.
+    public class DownloadProgressChangedEventArgs : ProgressChangedEventArgs
+    {
+        public DownloadProgressChangedEventArgs(long bytesReceived, long totalBytesToReceive,
+            int progressPercentage, object userState)
+                : base(progressPercentage, userState)
+        {
+            BytesReceived = bytesReceived;
+            TotalBytesToReceive = totalBytesToReceive;
+        }
+
+
+        //
+        // Summary:
+        //     Gets the number of bytes received.
+        //
+        // Returns:
+        //     An System.Int64 value that indicates the number of bytes received.
+        public long BytesReceived { get; }
+        //
+        // Summary:
+        //     Gets the total number of bytes in a System.Net.WebClient data download operation.
+        //
+        // Returns:
+        //     An System.Int64 value that indicates the number of bytes that will be received.
+        public long TotalBytesToReceive { get; }
+    }
+}

AutoUpdater.NET/FileDownloadClient.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace AutoUpdaterDotNET
+{
+    public abstract class FileDownloadClient : IFileDownloadClient
+    {
+        /// <summary>
+        /// The required constructor for the class.
+        /// </summary>
+        /// <param name="type"></param>
+        public FileDownloadClient(FileDownloadClientType type)
+        {
+            this.Type = type;
+        }
+
+
+        public virtual FileDownloadClientType Type { get; private set; }
+
+
+    }
+}

AutoUpdater.NET/FileDownloadClientType.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace AutoUpdaterDotNET
+{
+    /// <summary>
+    /// Identifies the type of download client required to retrieve the 
+    /// update file, i.e. WebClient, SFTP, etc.
+    /// </summary>
+    public enum FileDownloadClientType
+    {
+        /// <summary>
+        /// The type of client to use is unknown.
+        /// </summary>
+        Unspecified = 0,
+
+        /// <summary>
+        /// The update process will use the Web Client for 
+        /// a traditional HTTP(S) file download.
+        /// </summary>
+        WebClient = 1,
+
+        /// <summary>
+        /// The update process will use an SSH client to connect 
+        /// to a secure FTP site that is hosting the update file.
+        /// </summary>
+        SFTPClient = 2
+    }
+}

AutoUpdater.NET/IFileDownloadClient.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace AutoUpdaterDotNET
+{
+    public interface IFileDownloadClient
+    {
+        FileDownloadClientType Type { get; }
+
+
+    }
+}