Code Signing Certificate Expired: Can Previously Signed Software Still Run Normally?

The "validity period" of a code signing certificate mainly affects the trust status of newly signed files. The impact on already signed files depends on two scenarios:

• Timestamp Not Enabled: If no timestamp was added at the time of signing, after the certificate expires, the system will consider the signature invalid.
• Timestamp Enabled: If a timestamp was enabled at the time of signing, the system will verify "whether the certificate was within its validity period at the time of signing" — even if the certificate has expired, as long as the timestamp is valid, the signed file will still be trusted.