DOTNETCORE: connecting with private key file >> NotSupportedException at at System.Security.Cryptography.HMAC.HashFinal()

[mmacagno]

DOTNETCORE 3.1, with SSH.NET

I can successfully connect to a remote host with username and private key using Filezilla.
The same credentials and private key used with SSH.NET give me an exception.

The Exception seems to be some internal issue and not sure what to do to address it.

Can anyone help?

Exception:

Accessing a hash algorithm by manipulating the HashName property is not supported on this platform. Instead, you must instantiate one of the supplied subtypes (such as HMACSHA1.)

" at System.Security.Cryptography.HMAC.HashFinal() in //src/System.Security.Cryptography.Primitives/src/System/Security/Cryptography/HMAC.cs:line 68\r\n at Renci.SshNet.Security.Cryptography.HMACSHA1.HashFinal()\r\n at System.Security.Cryptography.HashAlgorithm.CaptureHashCodeAndReinitialize() in //src/System.Security.Cryptography.Primitives/src/System/Security/Cryptography/HashAlgorithm.cs:line 115\r\n at Renci.SshNet.Session.SendMessage(Message message)\r\n at Renci.SshNet.Session.Connect()\r\n at Renci.SshNet.BaseClient.CreateAndConnectSession()\r\n at Renci.SshNet.BaseClient.Connect()\r\n at ... (my code)

Exception type:
{Name = "PlatformNotSupportedException" FullName = "System.PlatformNotSupportedException"} Assembly: {System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e} AssemblyQualifiedName: "System.PlatformNotSupportedException, System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e" Attributes: Public | Serializable | BeforeFieldInit BaseType: {Name = "NotSupportedException" FullName = "System.NotSupportedException"} Cache: {System.RuntimeType.RuntimeTypeCache} CacheIfExists: {System.RuntimeType.RuntimeTypeCache} ContainsGenericParameters: false CustomAttributes: Count = 4 DeclaredConstructors: {System.Reflection.ConstructorInfo[4]} DeclaredEvents: {System.Reflection.EventInfo[0]} DeclaredFields: {System.Reflection.FieldInfo[0]} DeclaredMembers: {System.Reflection.MemberInfo[4]} DeclaredMethods: {System.Reflection.MethodInfo[0]} DeclaredNestedTypes: {System.Reflection.TypeInfo.<get_DeclaredNestedTypes>d__22} DeclaredProperties: {System.Reflection.PropertyInfo[0]} DeclaringMethod: '((System.RuntimeType)exception.GetType()).DeclaringMethod' threw an exception of type 'System.InvalidOperationException' }

CODE:
` SftpClient client = null;
MemoryStream stream = null;
StreamWriter writer = null;

        try
        {
            stream = new MemoryStream();

            writer = new StreamWriter(stream);
            writer.Write(
                "-----BEGIN RSA PRIVATE KEY-----" + "\n" +
                "MIIEpAIBAAKCAQEAsR7i+1kbPfZj2foKjRzM1gpf0OcjD2cNP/wBmwGmOjdQoW5/" + "\n" +
                ...
                "KcsxONtrmHQGPR8Oh8v94eL2pAC0rZ3rXb9YwVMpWBDyR6WGrw9OeQ==" + "\n" +
                "-----END RSA PRIVATE KEY-----");
            writer.Flush();

            stream.Position = 0;

            var keys = new PrivateKeyFile[] { new PrivateKeyFile(stream) };
            using var client = new SftpClient(this.config.Host, this.config.Port, this.config.Username, this.config.Password);
            
            client.Connect();
            return client.ListDirectory(remoteDirectory);
        }
        catch (Exception exception)
        {
            this.logger.LogError(exception, $"Failed to list directory: {remoteDirectory}");
            return null;
        }
        finally
        {
            stream?.Close();
            writer?.Close();
            client?.Disconnect();
        }`

[sfinkel]

I am encountering a similar issue with password authentication. I think the interesting commonality here is that the call to base.HashFinal() is somehow falling back to the abstract class HMAC instead of the subclassed parent.

In my case, this problem only occurs with .NET Core. If I run the same code under .NET Framework, it works as expected.

[mmacagno]

Interesting... maybe it's worth to cross post to dotnet core @ microsoft to see what's going on.

[mmacagno]

I am encountering a similar issue with password authentication. I think the interesting commonality here is that the call to base.HashFinal() is somehow falling back to the abstract class HMAC instead of the subclassed parent.

In my case, this problem only occurs with .NET Core. If I run the same code under .NET Framework, it works as expected.

Did you find a solution yet? I am still stuck with DOTNETCORE and unfortunately SSH.NET seems to be no longer maintained by the author. There are so many pull requests stuck to be approved...

[mmacagno]

I finally forked the repository and added the explicit support for .NET Core 3.1 and .NET 5.0 and was able to bypass this problem, due to .NET Core runtime issue (see above).

[darinkes]

Out of curiosity: I dont understand why should a library get built for netcoreapp?
From my understanding a library uses the lowest possible netstandard it can and other apps can use it. Regardless what .NET Core or .NET 5/6 Version they are using. Thats why the target got called "netcoreapp3.1", its for apps.

I have no issues using SSH.NET with .NET Core or .NET5/6 on Linux and Windows.

[Rob-Hague]

This is fixed in 2023.0.0 (by virtue of updated target framework support)