Whoa. Never would I have thought that a HSM allowed key exports.

I somehow assumed that real, non-toy HSMs involved dedicated generators as companion devices with heavily reduced attack surface, which generate and store private key material, are able to transfer it to the HSM proper (and to a paper backup), and are strictly kept offline after that.

Sometimes the world feels disappointing.

HSMs allows to have key stored with the option to disable key export. This means every cryptographic operation must be done by the HSM (commonly through pkcs 11 API).

HSMs have backup features and the data cannot be restored without a secret split among multiple secret holders (like https://en.m.wikipedia.org/wiki/Shamir%27s_secret_sharing). So a backup can be done on physical media and put in a safe.

It's a lot of things about key management, HSMs, pkcs interfaces to learn though.

What is possible with a HSM depends on the policies of the HSM and key objects (e.g. with PKCS#11). Vendors limit the "most open" policy that you can apply. For example, a FIPS 140-2 level 3 module can not offer unbounded key export (https://security.stackexchange.com/a/83981).

Using a HSM does _not_ guarantee that keys can not be exported. But the converse also holds, a key that is managed by a HSM can not necessarily be exported.

Yeah but if you invest in a HSM you're not going to leave the export passwords lying around of course. We have these Thales units too at work and there's a whole ritual around it. It's extremely unlikely that would happen.