Signing .NET DLL used as ActiveX Control

I have a COM visible .NET DLL file that is being used as an ActiveX control within a webpage shown in Internet Explorer.

The control itself is working开发者_Go百科 perfectly (though with some caveats) when called via JavaScript code from a webpage.

The problem comes with signing the DLL and having it reliably accessible. I am (as far as I can tell) signing the project within Visual Studio. In the properties for the project's 'Signing', I created a .pfx file and am using it to sign the DLL.

Within Internet Explorer, no matter what I do, I cannot get Internet Explorer to let the ActiveX control load without manually going into the security settings and changing the 'Download unsigned ActiveX controls' and 'Initialize and script ActiveX controls not marks as safe for scripting' options to Enable/prompt.

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Seems the original issue had nothing to do with the signature of the file, but in the implementation of IObjectSafety. For IE to allow it to be loaded, I needed to properly implement that interface, and it worked fine (even without a valid signature).

Simple example:

[ComImport()]
[Guid("CB5BDC81-93C1-11CF-8F20-00805F2CD064")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
interface IObjectSafety
{
    [PreserveSig()]
    int GetInterfaceSafetyOptions(ref Guid riid, out int pdwSupportedOptions, out int pdwEnabledOptions);

    [PreserveSig()]
    int SetInterfaceSafetyOptions(ref Guid riid, int dwOptionSetMask, int dwEnabledOptions);
}

And the class itself:

[ProgId("Testing.Test")]
[ClassInterface(ClassInterfaceType.AutoDispatch)]
[ComVisible(true)]
public sealed class Test : IObjectSafety
{
    #region Saftey Interface
    private const int INTERFACESAFE_FOR_UNTRUSTED_CALLER = 0x00000001;
    private const int INTERFACESAFE_FOR_UNTRUSTED_DATA = 0x00000002;
    private const int S_OK = 0;

    [ComVisible(true)]
    public int GetInterfaceSafetyOptions(ref Guid riid, out int pdwSupportedOptions, out int pdwEnabledOptions)
    {
        pdwSupportedOptions = INTERFACESAFE_FOR_UNTRUSTED_CALLER | INTERFACESAFE_FOR_UNTRUSTED_DATA;
        pdwEnabledOptions = INTERFACESAFE_FOR_UNTRUSTED_CALLER | INTERFACESAFE_FOR_UNTRUSTED_DATA;
        return S_OK;
    }

    [ComVisible(true)]
    public int SetInterfaceSafetyOptions(ref Guid riid, int dwOptionSetMask, int dwEnabledOptions)
    {
        return S_OK;
    }
    #endregion

    [ComVisible(true)]
    public string TestString
    {
        get
        {
            return 'A Test';
        }
    }
}

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For IE to download a signed ActiveX control it must trust the signature, i.e. the certificate must be a code-signing certificate issued by one of the Trusted Root Certification Authorities listed in Internet Explorer. (See Tools | Internet Options | Content | Certificates.)

If you want this to work everywhere you'll need to buy a certificate from one of the pre-installed Trusted Roots (e.g. Verisign).

If this is intended to work on an intranet your company can create its own self-signed certificate and push it out to all the browsers.

If you're just testing you can create your own self-signed root and install it in IE yourself.

(Even if signed correctly I'm not sure that recent versions of IE will automatically install any ActiveX control without asking the user first.)