archimag0

So it actually turns out that on Android if you opt out of ads personalisation, the app still sends the advertising ID, but also sends in the JSON "advertising_tracking_enabled: false", which is not so reassuring. See Privacy International's talk here: https://media.ccc.de/v/35c3-9941-how_facebook_tracks_you_on_...

Huh, good to know. In that case I'm not sure. What is your last issue?

Well, on closer inspection it seems like the MAC isn't actually an HMAC, but just SHA3. And since the padding isn't verified (because it can't be) that leaves it open to simple extension/truncation attacks (Crytopals challenges 29 and 30)?

2. Is the attack related to the unauthenticated lengths already mentioned or is there something else there?

Apart from what he points out in the article ("The PIC client is susceptible to a MitM (Man In The Middle) attack because it does not verify if the public key sent by a server is from a trusted party")

1. Weird encryption which seems to be XORing the plaintext against the same encrypted IV?

2. Using random padding instead of PKCS5 or similar?

3. Using memcmp instead of CRYPTO_memcmp or similar?

Thanks for replying - I just wanted to dive in and get stuck into the levels, but found the UI so confusing that I just gave up - particularly as someone with no AVR experience, and with the tutorial dying half way through.

The biggest pain point was figuring out what was executing. As I mentioned, I would be playing around in the compiler, hit compile and save, and then attempt to run it in the debugger. The 'run' command either seemed to have no effect, or would run a previously compiled program, not the one I'd just written. Even typing 'reset' didn't help.

The memory didn't seem to be updating in real time either, which made things even more confusing!

Running in Firefox if that makes a difference.

- Can't have the compiler side by side with the debugger, even though there's plenty of room on the screen

- When the PC jumps, the highlighted instruction doesn't follow, leaving you lost when stepping through a program

- Can't hit enter on a blank line to repeat previous command

- No 'finish' debugger command?

- Seem to end up in random functions when stepping over simple instructions

- Am I supposed to type 'flash' or 'run' to execute my compiled program? Sometimes the one I just compiled gets executed, sometimes the one I compiled previously - how can we view what's being executed?

I really enjoyed microcorruption, and thought that UI was fine, but this feels like a step backwards.

Is the server struggling again? None of my input into the UI seems to be having an effect.