Unable to sign an imported msi.dll assembly using tlbimp

Question

This seems so trivial, yet I can't get it to work..

I have an msi.dll wrapper (named Interop.WindowsInstaller.dll) which I need to sign. The way to do it is by signing it upon import (this specific case is even documented in MSDN: http://msdn.microsoft.com/en-us/library/zec56a0w.aspx).

BUT - no matter how I do it (w/ or w/o a keyfile, w/ or w/o adding "/delaysign"), the generated assemly's size is always 36,864 bytes and when viewing the DLL's properties there is no "Digital Signatures" tab (needless to say - the DLL is NOT signed).

What am I missing here?? (... HELP!...)

Answer 1

[Note: Eventually I got a hint from Karel Zikmund on this thread, which helped me solve the mystery. I'll paste my reply here - for the greater good].

So, I used the following line to sign-upon-import the assembly:

tlbimp C:\WINDOWS\system32\msi.dll /out:Interop.WindowsInstaller.dll /keyfile:MyKey.snk

I then copied the file to the appropriate location and built the project, but each time the build failed on the following error: Assembly generation failed -- Referenced assembly 'Interop.WindowsInstaller' does not have a strong name.

I thought the problem was with the tlbimp line, but after reading Karel Zikmund's reply and verifying that the DLL is strong-named (using sn -vf Interop.WindowsInstaller) I found out the problem.

Adding a reference to the "Microsoft Windows Installer Object Library" COM object actually planted a code block into the .csproj file. I didn't realize it, but this block caused the DLL file to be regenerated from scratch upon each time the project was built. The generated file, of course, was not strong-named anymore.

The way I resolved it was to remove the reference to "Microsoft Windows Installer Object Library" from the project, and add a direct file reference to the imported (and already signed) Interop.WindowsInstaller.dll file.