What happens after 6 hours? Let's say I capture all the data from all the sensors and decrypt it with a 24 hr lag. I don't get a real-time info, but i collect all the patterns and whatever long-term data that's accidentally sent out.
The data needs to reach a server within that period (the real period is much shorter: 5 minutes currently, but it might be 1-2 hours in the future); if it comes in after that, the server will find it invalid and drop it. We currently have it completely secure (modern ECC for instance): we have created a hybrid which refreshes a low power latency/power private key using the traditional means which gives us windows long enough to have low latency and lower power usage while ensuring the encryption holds. Something globally accepted would be better obviously. We have many more prototypes of things we evaluated ourselves but need help (if you know someone with these credentials) with just to solve the latency and power consumption issue.
So the server and device securely agree on something like TOTP list (weak keys with expiration date), so intermediate data can be authenticated within those time windows? But if that applies to encryption too, then won't later bruteforced decryption pose a threat?