Tenement Farming and Cloud HSMs

I have been working on using cloud FPGAs as replacements for HSMs for this reason. They are inherently single-tenant when you use them, and if you do everything right, you can have them cryptographically shred their internal state when they are reprogrammed. You don't have as many physical security promises (but you don't own Amazon's HSM anyway, so I would argue that FIPS 140-3 is not relevant from the physical security angle), but they are a lot more isolated from other users and from meddling by Amazon insiders than Amazon's Cloud HSM is.

The drawback is that they are very expensive, so you have to be really paranoid to want to use them, and they are new enough and complicated enough that you have to trust us and our auditors to have done everything right.

The design pattern of maximal separation of thing that holds private keys from thing that needs access to secrets is great. That's my main lesson learned from this article.

I think this space is ripe for significant evolution.

Authors point re hashicorp vault being marginally better than checking keys into source control hits home. Eg often infra is one stolen ssh key away from having code committed that can select * from vault. That also comes with crappy provenance that doesn't integrate well with gitops.

My hopeful view is that we can incrementally fix this bottom-up:

1. ssh should use the mobile phone biometrics as HSM and expose that via ssh-agent

2. From there simple projects should use sops to commit their ssh encrypted secrets to git. I wrote https://github.com/tarasglek/github-to-sops to make it easy to share secrets this way. One can even use sshd private keys to separate secrets for infra from dev ones.

3. For more complex projects one can loop aws kms type hsms.

4. For more complex orgs we then need to borrow some cleverness from crypto ecosystem as they actually made a lot of progress in various tricks to derive trust/ownership...but instead of stupid blockchain one should keep using git.

5. This then can be extended down to database level mods where one could extend row-level ACLs with signature-based provenance checks in 4

Note I am in no way a security person. Just have a desire for someone to make this problem go away for us mere mortals.

I don't think the term "HSM" really carries much meaning, and if you're familiar with the space, you probably won't find it too shocking to hear someone claim that Amazon has put more cryptographic expertise to bear on KMS than has been embedded in any of the well-known rackmount HSMs.

I am personally involved in procurring HSMs for regulatory reasons. I would be more than happy to deploy an alternative solution that's demonstrably better suited for threats in todays typical cloud environments and fight it out with the regulator. The author sadly doesn't answer that question. Anyone having an idea?

With rack mount HSM, I can monitor for physical access with security camera.

When it is on cloud, who knows what?