Meta built large-scale cryptographic monitoring

Neither: it's because (overgeneralizing) there are bounds on the number of times nonces can be generated under a key without risk of collision, which in AEAD constructions is a devastating event.

If you want to read more about cryptographic key wear out, Soatok wrote an excellent explainer on this a few years ago https://soatok.blog/2020/12/24/cryptographic-wear-out-for-sy...

You can absolutely learn it. Elasticsearch, Logstash, Kibana, Grafana, Prometheus. Set up a local Docker Compose deployment of the full stack and pass through some dummy events. Write an app to generate synthetic load. Play around with aggregations and visualizations. Tech blogs use a lot of buzzwords but you just need to know the fundamental concepts.

Never worked at facebook, but typically at a large companies, things like this are sent with instructions on how to go about doing that, and most often just making sure your dependencies are updated so next run of automated build/deploy will pick up the change.

When I was there, the experience here would've been more like "you see some comms on Workplace saying this thing went live".

For a small number of people, it would look like "It's your oncall week, and you unexpectedly receive a large diff stack from a complete stranger". Most engineers at Meta won't touch anything related to C++ during their tenure there, and you can safely assume all this stuff would be abstracted away from them.

If you are on a C++ project, odds are that your experience here would be "I'm on-call and got pinged by a random person saying they were submitting a diff stack to implement this feature". Except if your project was sufficiently large, you'd probably have known about this ages ago so the diff wouldn't actually be unexpected, nor the submitter a complete stranger.

You’d be calling libraries that are vetted by the security team. Engineering at Meta is a lot like coloring with crayons. It’s very limiting but the infra does a lot for you.

triage and redirect to L7+ colleague

In my experience with the cryptographic security space at Facebook, what happens is the security team reaches out to you and starts a conversation. You collaboratively establish the severity, acceptable mitigation options, and appropriate timeline. There might be a little bikeshedding over various degrees of ideal option (it's more fun for the crypto guys that way). They might volunteer to do the work. You review the diffs, they're good, it lands.

They're smart people and the team knows how to collaborate with random infra/product teams.

How it really works - security team files a task to replace a crypto algorithm in your team's code and gives you a SLA deadline of 6 months. 6 months later, no one has touched it, so they escalate. Your manager says "we are short staffed" and requests an extension. They give you another 3 months and write a detailed guide on what lines to change. 3 months later everyone they originally spoke to has left the team, and the new people don't have any context. They try and figure it out but the security person has also left the team. No one remembers what the task was originally created for. A year later the service that was using the old algorithm is itself deprecated.