Protection of keys of encrypted datasets

[wq9578]

Are there any protection mechanisms in place that would prevent that loaded keys are saved to disk in case of a swap / hibernation / core dumps?
For example, swap or hibernation data is stored in the VM volume, and even when FileVault is activated, the VM remains unencrypted:

FileVault 2 encrypts only the OS/User volume while leaving Preboot, Recovery, and VM unencrypted.

This means sensitive key material could be exposed if stored unencrypted in the case of swap or hibernation.

The /cores directory (link 1, link 2) seems in my case to be stored in the Data volume (mounted on /System/Volumes/Data), which is encrypted.

But also here it would be interesting to know whether a ZFS key might be saved there, too, in case of a core dump caused by a crash.