Code Signing

Code signing is cryptographically stamping an application with a verified identity, so the operating system can prove who published it and that it hasn't been tampered with since.

It matters because both major desktop OSes now treat unsigned software as suspect by default: macOS's Gatekeeper warns that unsigned apps "can't be verified", and Windows SmartScreen interposes its blue "Windows protected your PC" wall. Users read both as "this might be malware", and many stop there.

Signing requires a certificate from a trusted authority: on macOS, a Developer ID Application certificate from Apple's Developer Program ($99/year), typically paired with notarization; on Windows, a code-signing certificate, increasingly via cloud services like Azure Trusted Signing rather than physical USB tokens.

For the full picture of how signing fits into shipping, see code signing and auto-updates explained. Deskifier includes signing on both platforms, so apps built with it install without warnings.