App Signing with Desktopr
Code signing is a security technology used to certify the authorship and integrity of software. Whether you are developing for macOS or Windows, signing your application is essential for a professional and secure distribution.
Note:
Desktopr builds unsigned apps happily — signing is optional and uses only your own certificates, kept as secrets in your repository. But for public distribution you want signed builds: unsigned apps are blocked or flagged on first launch.
Signing in Desktopr is configured with repository secrets used by the build workflow:
| Purpose | Secrets |
|---|---|
| Windows code signing | WINDOWS_CERTIFICATE (base64 .pfx), WINDOWS_CERTIFICATE_PASSWORD |
| macOS code signing | APPLE_CERTIFICATE (base64 .p12), APPLE_CERTIFICATE_PASSWORD, APPLE_SIGNING_IDENTITY |
| macOS notarization | APPLE_ID, APPLE_PASSWORD (app-specific password), APPLE_TEAM_ID |
If a platform's secrets are missing, that build is simply unsigned; if a set is incomplete, the workflow fails before building. Credentials are never workflow inputs and are never printed.
1. Establishing Developer Trust
Digital signatures act as a virtual "ID card" for your software.
- macOS: Links the app to your Apple Developer ID.
- Windows: Identifies the legal entity or individual developer via a Certificate Authority (CA). Without this, the operating system treats the software as coming from an "Unknown Developer," which can lead to users abandoning the installation.
2. Preventing Security Warnings
Both operating systems have strict security filters to protect users from malicious software.
- macOS (Gatekeeper): Unsigned apps are blocked by default. Users must go through deep system settings to bypass the warning, which creates a high barrier to entry.
- Windows (SmartScreen): When a user downloads an unsigned
.exeor.msi, Windows SmartScreen displays a prominent blue warning: "Windows protected your PC." Signing your app (especially with an EV certificate) helps establish reputation and removes this warning.
3. Guaranteeing Software Integrity
A digital signature creates a cryptographic "seal" over your code.
- If a third party, a virus, or malware modifies even a single byte of your application after it has been signed, the signature becomes invalid.
- The operating system will then alert the user that the app has been tampered with, preventing the execution of compromised code.
4. Seamless User Experience
Signing ensures that the installation process is smooth and professional.
- Notarization (macOS): Once signed, apps are sent to Apple for notarization. This automated scan confirms the app is free of known malware, allowing it to run with a simple double-click.
- Silent Updates: Signed apps can often update themselves more easily, as the system recognizes the new version's signature as matching the previous one.
5. Access to System Features
Modern OS features are often restricted to signed applications:
- macOS: Required for iCloud, Push Notifications, and Hardened Runtime.
- Windows: Necessary for certain kernel-mode drivers and hardware integrations.
Summary: Signing your app is the only way to prove you are the author, ensure your code hasn't been altered, and provide your users with a warning-free installation experience.