Not every piece of code needs to be signed. Should my ancient copy of Doom 2 stop working because it's not with the times? Or a level editor for it? Or an old turboC compiler?

Some software lives a LONG time and it's fine, and it's up to the user whether that software is still useful to them or not.

Seriously how many posts do we see on hacker news about like "We rebuilt this ancient machine from the 1970s to learn about it." People care about computing history. Not everyone, but there's no reason to force your software to break because the calendar rolls over. Remember Y2K? Things often live a LONG time. People are still actively writing Fortran and COBOL. The short-sightedness of this is amazing, as is the condescending "we know what's best for you" security argument.

Typically software signatures are not just pass/fail, but used to give audited entitlements for API.

So a secure system would let you run Doom, but could forbid:'

- Access to the filesystem outside the application domain due to potential for exfiltrating or destroying user data

- Likewise, access to global system data may be limited

- Access to the network due to (raw TCP/UDP) traffic not having been audited for security, and the network connectivity being usable for exfiltration

- Access to run full-screen due to the ability to perform user phishing attacks by presenting fake UI.

- The ability to disable system-registered keyboard sequences (on windows, such as the windows key or sticky keys)

- Access to mouse events outside its window

- Access to key scan data, although this likely will be emulated

- Access to change display color modes to e.g. 256 color indexed, although this will likely be emulated as well

Right but that's why we have sandboxes and virtual machines. There's no need to use a calendar date to enforce security.