[guardian-dev] The sound of an encrypted audio stream

[Lee Azzarello]

Hello all,

There have been some conversations recently on IRC and on the web
about VBR audio codecs and plaintext recovery.

It's an interesting conversation and one which will change a lot in
our times. While I was testing some video call clients, I saw a bug
between a custom build of Linphone on Android and a nightly of Jitsi
on OS X where Linphone tried to play back the encrypted audio through
the speaker without first decrypting it.

This is what a SRTP audio stream sounds like to a wiretap. The codec
is speex at 16 kHZ, I believe it is VBR but I'm not certain.

http://ge.tt/9FG7Tem/v/0?c

-lee