Caliptra allows enough measurements to be stashed to exceed the 2kB certificate threshold within DPE

[nquarton]

The certificate returned by certify key has a 2kB limit. This limit can be exceeded when stashing more than ~8 measurements.

In fixing this, a test needs to be added that stashes the maximum number of measurements to confirm DPE can support it.

[ericeilertson]

Is the 2kB limit due to a DPE specification limitation, or is this a limit due to our current implementation in Caliptra? I think there are cases we may need to stash a few dozen measurements, so I'd like to see this increased if possible.

[nquarton]

Is the 2kB limit due to a DPE specification limitation, or is this a limit due to our current implementation in Caliptra? I think there are cases we may need to stash a few dozen measurements, so I'd like to see this increased if possible.

This was a limit in the DPE implementation. I can't say for sure if this is requiring a spec change. But this size is being increased to 6k in the 1.2 FW to allow for the full 32 measurements.

[jhand2]

It's a profile limitation. It's been increased in both the profile spec & implementation.

Btw, we'll probably need to revisit this again for 2.0. I'm planning some ABI changes to make the sizes more flexible in the next revision.