Zoom rolled their own encryption scheme, transmit keys through servers in China

Post by pdwcyl » Sat, Apr 04, 2020, 2:02 AM UTC

thrwaway69 wrote: post #168

Leary wrote: post #136

Earlier quoted context omitted.

While you wait for his response: https://www.newyorker.com/news/letter-from-silicon-valley/th...

At first, the site attracted about sixteen hundred daily visitors, and Graham moderated and maintained it himself. Today, around five million people read Hacker News each month, and it’s grown more difficult to moderate. The technical discussions remain varied and can be insightful. But social, cultural, and political conversations, which, despite the guidelines, have proliferated, tend to devolve. A recent comment t…

Post by barrkel » Sat, Apr 04, 2020, 2:06 AM UTC

sdenton4 wrote: post #205

tptacek wrote: post #162

Earlier quoted context omitted.

I don't know audio well enough to answer this, but you can play with it directly; it took about 7 minutes for me to throw a trivial Go program together to AAC-encode a WAV of half a minute of speech; the only repeated 16-byte blocks I got were a couple runs of zeroes. The trick with ECB is that you're relying on 128-bit blocks of plaintext repeating with perfect alignment, and, to do anything useful with it, those re…

For audio, you don't want to send a wav file over the line, as it's incredibly wasteful. Once it's reasonably encoded, you necessarily end up with a lower entropy steam... So should still have some version of "solid blocks of color", especially for silence. (Exact details depend on the codec, though.)

Post by stouset » Sat, Apr 04, 2020, 2:36 AM UTC

monocasa wrote: post #87

stouset wrote: post #53

Earlier quoted context omitted.

Compression already makes a compressed file roughly indistinguishable from random noise (module access to the decompressor). So the patterns have been removed. That doesn’t make this good , but it means that one specific example isn’t immediately applicable.

There's more in the stream than just compressed data. There'll be metadata info that you can make reasonable guesses about. ECB mode lets you take that information and apply it to other blocks in the ciphertext.

Post by stouset » Sat, Apr 04, 2020, 2:42 AM UTC

_jal wrote: post #139

monocasa wrote: post #87

Earlier quoted context omitted.

There's more in the stream than just compressed data. There'll be metadata info that you can make reasonable guesses about. ECB mode lets you take that information and apply it to other blocks in the ciphertext.

This thread is an excellent illustration of why you don't want your encryption implemented by merely good coders. You need people who know what they are doing.

Post by killjoywashere » Sat, Apr 04, 2020, 2:54 AM UTC

barrkel wrote: post #213

sdenton4 wrote: post #205

Earlier quoted context omitted.

For audio, you don't want to send a wav file over the line, as it's incredibly wasteful. Once it's reasonably encoded, you necessarily end up with a lower entropy steam... So should still have some version of "solid blocks of color", especially for silence. (Exact details depend on the codec, though.)

Lossy compression reduces entropy, I'd expect fewer repeats and more of what looks like random data in any compression worth its salt. Thomas also mentioned AAC, not PCM. I agree on the silence, but it would come up as smaller packets, not repeated packets, IMO. And then we're back to timing analysis of speech.