https://news.ycombinator.com/item?id=12089993 … < On WhatsApp not working in Saudi. Calls are filtered by firewall, so the UI just blocks them rather than timeout.
-
-
Better would be actively working around the firewall, e.g. making it computationally expensive to distinguish encrypted calls.
-
the data flow pattern of a call is unique and hard to change. Steady stream of encrypted data is most likely a call
-
Suppose as an example the call were mp3 streams. Encode the ciphertext as quantized DCT coeffs in valid mp3 streams.
-
Now you need audio analysis (moderately expensive for firewall) to determine if the call is encrypted.
-
you can block any audio stream which are not known protocol. If I understand you correctly, you pay a lot BW for stegn
-
Steganography to fool humans or smart analysis tools costs a lot in BW. OTOH what I described is just a few % BW cost.
-
then I don't understand why can't you sample the mp3 and block ones with high entropy in DCT coeff
-
Roughly the same reason gzipping an mp3 doesn't get you much.
- 2 more replies
New conversation -
Loading seems to be taking a while.
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.