Dan
Posts: 4524
Joined: Wed Apr 24, 2013 3:51 pm

Solution for Handling Files with Invalid or Unrecognized Signatures

Hello Advanced Installer Community,

I recently encountered an issue during the build process with Advanced Installer and wanted to share my experience, hoping it might help others facing similar challenges.

The Problem:
During a project build in Advanced Installer, I received a warning indicating that a certain DLL file was either already signed or had an invalid signature. This was puzzling because, when I checked the file properties in Windows Explorer, the "Digital Signatures" tab was missing, suggesting that the file wasn't signed at all.
AI Build Error.png
AI Build Error.png (100.4 KiB) Viewed 46756 times


Investigation:
This behavior suggested that although Advanced Installer detected some form of signature, it was not valid or in a recognizable format. This discrepancy can occur due to a variety of reasons, such as partial signing, signing interruptions, or even certain types of file corruption.

No tool report the file as signed e.g. Sigcheck , but still signing on that fails.

After some research, I discovered a third-party tool that proved to be incredibly useful for this specific issue. The tool is available on XDA Forums, and it's called DelCert (a signature stripping tool). You can find it here.

Please note: Always exercise caution when downloading and using third-party software, ensuring it's from a reputable source to avoid any security risks.


Steps Taken:


  • Using DelCert: I used the DelCert tool to remove the corrupted signature from the file. The process was straightforward and effectively stripped the unrecognized signature, allowing me to proceed without the warning from Advanced Installer.
    Delcert Remove Signature.png
    Delcert Remove Signature.png (75.38 KiB) Viewed 46756 times
  • Re-signing in Advanced Installer: With the invalid signature removed, I was then able to successfully sign the DLL during the build operation in Advanced Installer, without encountering any previous warnings.
    Success Build.png
    Success Build.png (103.47 KiB) Viewed 46756 times
  • Final Verification: After the build and signing process, I verified the new signature through both Windows Explorer and SignTool to ensure everything was correctly applied and recognized.


Conclusion:
If you're encountering warnings about invalid signatures or pre-signed files in Advanced Installer and cannot find or remove these signatures through conventional means, consider using a tool like DelCert. Just remember to verify the tool's source and integrity before use.

I hope this post helps anyone who might be struggling with similar signature issues. Feel free to share your experiences or ask questions if you're facing this or related problems.

Best regards,
Dan
Dan Ghiorghita - Advanced Installer Team
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