Issue Summary

Description:

AzureSignTool currently lacks support for signing Excel add-in files (.xlam). Attempting to sign .xlam files using AzureSignTool results in an error message The file cannot be signed because it is not a recognized file type for signing or it is corrupt.

Steps to Reproduce:

1. Attempt to sign an Excel add-in file (.xlam) using AzureSignTool.
2. Observe the error message indicating the lack of support for xlam files.

Expected Behavior:

AzureSignTool should have support for signing .xlam files, similar to how signtool.exe with msosipx.dll registered works.

Additional Information

Workaround:

Currently, a potential workaround is to use signtool.exe with msosipx.dll registered. This allows for the successful signing of .xlam files.

Steps to Use Workaround:

1. Download officesips from https://www.microsoft.com/en-us/download/details.aspx?id=56617
2. Follow instructions for installation and registration of msosipx.dll using command regsvr32 msosipx.dll
3. Install signtool using ClickOncePublishing component from Visual Studio Installer
4. Utilize signtool.exe to sign the .xlam file.

Environment Details:

• AzureSignTool Version: 4.0.1
• Operating System: Windows 22H2

Additional Context

According to Digicert article Signtool (64-bit) does not support xlam-files.