A few days ago, some Mac App Store users got a surprise: apps that had been installed for a long time were no longer working, with an unclear message that the app is damaged and can’t be launched.
A certificate problem… but not only
One of the reasons for this error comes from an issue of expired certificates: some of those used to sign application code were only valid until February 6 or 7, 2023 (there are several). The error in case of invalid certificates is unfortunately not very explicit: the system considers that the application is damaged — understand “ It has been modified — and refuses to throw it.
But various sources indicate that the problem of dates is not the only problem, as reported Der Flounder et TechCrunch. In the first case, it was noted that applications signed with a valid certificate did not work, and in the second, an explanation is given: the fact that Apple has tightened security.
Says TechCrunch, therefore, the problem comes from the way of signing. The firm switched to SHA-2 encryption in September, when older apps used SHA-1 (notoriously weak). And obviously, some old applications integrate a library that is too old to validate the new certificates, which prevents them from being replaced and therefore an error at launch. In theory, developers can of course update their applications to correctly validate certificates, but this is not systematic: some apps have been abandoned over time. In this case, you can try a reinstallation, if the application is still available in your purchases.