ERROR: " This copy of the Install OS X Mavericks application can't be verified. it may have been corrupted or tampered with during downloading"

The error messsage was thrown when running OS X Mavericks Installer (previously downloaded from App Store).

For my case, this is because the installer file was downloaded years ago so the certificate come with it had expired. I should re-download it but it was no longer available on App Store.

Thus, the workaround is to change my machine's date (clock) to the release year of OS X Mavericks. It's easy to change the date if the installer is launched from the running OS X prior to Mavericks, but if it is launched from Recovery mode, it invovles running commands in Terminal (there's enough posts on the net about this though).