Clarify Microsoft Store automatic code signing for MSIX packages

[Copilot]

Documentation did not explicitly state that Microsoft Store automatically signs MSIX packages, leaving developers uncertain about certificate requirements—particularly those using USB tokens unable to export .pfx/.cer files.

Changes

app-package-requirements.md

• Added "Code signing for Microsoft Store submissions" section
• Lists what is NOT required: certificates, .pfx/.cer files, USB tokens, HSMs
• Distinguishes Store vs. non-Store distribution requirements

app-certification-process.md

• Updated Publishing section to clarify Store performs automatic signing with Microsoft certificate
• Separated concepts into distinct sentences for clarity

get-started-with-the-microsoft-store.md

• Added FAQ: "Does the Microsoft Store provide code signing for my app?"
• Explains automatic signing replaces any existing signature
• Clarifies certificate requirements only apply to non-Store distribution

Key Points

Store submissions require only package files (.msix, .msixupload, .msixbundle, etc.). The Store re-signs all packages with a Microsoft certificate during publishing after certification passes. This eliminates the need for developers to purchase or manage code signing infrastructure for Store distribution.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Code signing for .msix files</issue_title>
<issue_description>The packager asks for .pfx or .cer files but I use a USB Token and cannot export from that. However I see an option for using the cert provided by the Microsoft Store developer account. Not having a Store account I cannot verify that, and need to know before committing.

Does the Store provide code-signing for my app?</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Code signing for .msix files #5696

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[learn-build-service-prod]

Learn Build status updates of commit 6ac882e:

✅ Validation status: passed

File	Status	Preview URL	Details
hub/apps/publish/faq/get-started-with-the-microsoft-store.md	✅Succeeded
hub/apps/publish/publish-your-app/msix/app-certification-process.md	✅Succeeded
hub/apps/publish/publish-your-app/msix/app-package-requirements.md	✅Succeeded

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[learn-build-service-prod]

Learn Build status updates of commit 04af857:

✅ Validation status: passed

File	Status	Preview URL	Details
hub/apps/publish/faq/get-started-with-the-microsoft-store.md	✅Succeeded
hub/apps/publish/publish-your-app/msix/app-certification-process.md	✅Succeeded
hub/apps/publish/publish-your-app/msix/app-package-requirements.md	✅Succeeded

For more details, please refer to the build report.