winapp-signing

When to use

Use this skill when:

• Generating a development certificate for local MSIX signing and testing
• Installing (trusting) a certificate on a machine so MSIX packages can be installed
• Signing an MSIX package or executable for distribution

Prerequisites

• winapp CLI installed
• Administrator access required for cert install (trusting certificates on the machine)

Key concepts

Publisher matching: The publisher in your certificate (e.g., CN=MyCompany) must exactly match the Publisher attribute in appxmanifest.xml. Use --manifest when generating to auto-match.

Dev vs. production certs: winapp cert generate creates self-signed certificates for local testing only. For production distribution (Microsoft Store or enterprise), obtain a certificate from a trusted Certificate Authority.

Default password: Generated certificates use password as the default PFX password. Override with --password.

Usage

Generate a development certificate

# Auto-infer publisher from appxmanifest.xml in the current directory
winapp cert generate

# Explicitly point to a manifest
winapp cert generate --manifest ./path/to/appxmanifest.xml

# Set publisher manually (when no manifest exists yet)
winapp cert generate --publisher "CN=Contoso, O=Contoso Ltd, C=US"

# Custom output path and password
winapp cert generate --output ./certs/myapp.pfx --password MySecurePassword

# Custom validity period
winapp cert generate --valid-days 730

# Overwrite existing certificate
winapp cert generate --if-exists overwrite

Output: devcert.pfx (or custom path via --output).

Install (trust) a certificate

# Trust the certificate on this machine (requires admin/elevated terminal)
winapp cert install ./devcert.pfx

# Force reinstall even if already trusted
winapp cert install ./devcert.pfx --force

This adds the certificate to the local machine's Trusted Root Certification Authorities store. Required before double-clicking MSIX packages or running Add-AppxPackage.

Sign a file

# Sign an MSIX package
winapp sign ./myapp.msix ./devcert.pfx

# Sign with custom password
winapp sign ./myapp.msix ./devcert.pfx --password MySecurePassword

# Sign with timestamp for production (signature remains valid after cert expires)
winapp sign ./myapp.msix ./production.pfx --timestamp http://timestamp.digicert.com

Note: The package command can sign automatically when you pass --cert, so you often don't need sign separately.

Recommended workflow

1. Generate cert — winapp cert generate (auto-infers publisher from manifest)
2. Trust cert (one-time) — winapp cert install ./devcert.pfx (run as admin)
3. Package + sign — winapp package ./dist --cert ./devcert.pfx
4. Distribute — share the .msix; recipients must also trust the cert, or use a trusted CA cert

Tips

• Always use --manifest (or have appxmanifest.xml in the working directory) when generating certs to ensure the publisher matches automatically
• For CI/CD, store the PFX as a secret and pass the password via --password rather than using the default
• winapp cert install modifies the machine certificate store — it persists across reboots and user sessions
• Use --timestamp when signing production builds so the signature survives certificate expiration
• You can also use the shorthand: winapp package ./dist --generate-cert --install-cert to do everything in one command

Related skills

• Need to create a manifest first? See winapp-manifest to generate appxmanifest.xml with correct publisher info
• Ready to package? See winapp-package to create and sign an MSIX in one step
• Having issues? See winapp-troubleshoot for common error solutions

Troubleshooting

Error	Cause	Solution
"Publisher mismatch"	Cert publisher ≠ manifest publisher	winapp cert generate --manifest ./appxmanifest.xml to re-generate with correct publisher
"Access denied" / "elevation required"	cert install needs admin	Run your terminal as Administrator
"Certificate not trusted"	Cert not installed on machine	winapp cert install ./devcert.pfx (admin)
"Certificate file already exists"	devcert.pfx already present	Use --if-exists overwrite or --if-exists skip
Signature invalid after time passes	No timestamp used during signing	Re-sign with --timestamp http://timestamp.digicert.com

Command Reference

winapp cert generate

Create a self-signed certificate for local testing only. Publisher must match the manifest (auto-inferred if --manifest provided or Package.appxmanifest is in working directory). Output: devcert.pfx (default password: 'password'). For production, obtain a certificate from a trusted CA. Use 'cert install' to trust on this machine.

Options

Option	Description	Default
--export-cer	Export a .cer file (public key only) alongside the .pfx	(none)
--if-exists	Behavior when output file exists: 'error' (fail, default), 'skip' (keep existing), or 'overwrite' (replace)	Error
--install	Install the certificate to the local machine store after generation	(none)
--json	Format output as JSON	(none)
--manifest	Path to Package.appxmanifest or appxmanifest.xml file to extract publisher information from	(none)
--output	Output path for the generated PFX file	(none)
--password	Password for the generated PFX file	password
--publisher	Publisher name for the generated certificate. If not specified, will be inferred from manifest.	(none)
--valid-days	Number of days the certificate is valid	365

winapp cert install

Trust a certificate on this machine (requires admin). Run before installing MSIX packages signed with dev certificates. Example: winapp cert install ./devcert.pfx. Only needed once per certificate.

Arguments

Argument	Required	Description
<cert-path>	Yes	Path to the certificate file (PFX or CER)

Options

Option	Description	Default
--force	Force installation even if the certificate already exists	(none)
--password	Password for the PFX file	password

winapp cert info

Display certificate details (subject, thumbprint, expiry). Useful for verifying a certificate matches your manifest before signing.

Arguments

Argument	Required	Description
<cert-path>	Yes	Path to the certificate file (PFX)

Options

Option	Description	Default
--json	Format output as JSON	(none)
--password	Password for the PFX file	password

winapp sign

Code-sign an MSIX package or executable. Example: winapp sign ./app.msix ./devcert.pfx. Use --timestamp for production builds to remain valid after cert expires. The 'package' command can sign automatically with --cert.

Arguments

Argument	Required	Description
<file-path>	Yes	Path to the file/package to sign
<cert-path>	Yes	Path to the certificate file (PFX format)

Options

Option	Description	Default
--password	Certificate password	password
--timestamp	Timestamp server URL	(none)