Glossary/macOS Keychain & security

Code signing

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Code signing is the process of attaching a cryptographic signature to an app, tied to a developer's Apple Developer ID, so macOS can verify the app has not been altered since it was signed and can confirm who built it.

Why it matters

Code signing is also how the Keychain decides which apps are allowed to access a given entry without prompting every time, since access rules can be tied to a signed app's identity rather than just its name.

Is a signed app automatically safe?

Signing verifies identity and integrity, not intent, so it confirms who built the app, not that the app is trustworthy.

What happens if a signed app is modified after signing?

macOS detects the mismatch and will refuse to run it or will warn you, depending on the type of change.

Related

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