Fun with Timing Attacks (2024)

Edit: wait, it did complete now that I've not used the skip to demo link and read the article. "Benchmark complete! Using 29000 iterations". Maybe mention that it can take several minutes on a modern device? Or a progress indicator?

Now that I'm running the password guesser, the device does get warm in the usual spot for cpu load. Cool way to visualise the method! After five minutes, 6 out of 10 guesses have the right first character, and of those, 2 the right second character. Am I extrapolating correctly if I guess it'll need to do this 4 more times so some 20 minutes? Battery use is 30%./hour currently so about 10% of a full charge would be 1.1 Wh

Edit2: the number of correct prefixes is decreasing after 10~15 minutes. This will take forever

But yea, basically if a cache hit versus a memory roundtrip will result in different time values, then you can iterate over all 256 bytes (assuming ASCII) and when you have a cache hit for a specific value, the time should be much lower.

However, this also assumes you understand cache internals of the specific CPU and it means you need to know when caches fill up, why they fill up and how to do cache eviction. Knowing how to do cache eviction means that you need to know how many elements can be cached, and if I recall correctly that means you need to reverse engineer the cache size of the CPU. But once you can reliable evict values from the cache set and reliably fill them up, then the rough outline I mentioned above is possible.

Again, this is like 50% accurate since it has been a long while and I currently work in marketing as a data analyst (I like a mix of fluffy marketing/psychology talk and being deeply technical - if you feel the same way, feel free to reach out. My email is on my profile). There's some of what I described on this website (and a whole bunch more) [1]. I think the reverse engineering of cache lines was specifically in the accompanied paper.

[1] https://www.vusec.net/projects/glitch/

You can tweak the Thompson sampling to handle best-arm, like https://www.escholar.manchester.ac.uk/api/datastream?publica... "Ordered-Statistic Thompson Sampling". I am not sure if the pseudocode TS presented by OP winds up doing the same thing.

I can confirm it works in Chrome.