Eavesdropping on Encrypted Compressed Voice: “Impressive.”
David Robson has a writeup on New Scientist’s site that talks about recovering content based on packet size. Knowing how sounds are encoded can help the attackers guess at the sounds that led to the observed packet sizes.
The software breaks down a typed phrase to be listened for into its constituent sounds using a phonetic dictionary. A version of the phrase is then pasted together from audio clips of phonemes taken from a library of example conversations, before finally being made into a stream of VoIP-style packets.
Indeed. The short version is that this appears to be a creative application of traffic analysis to recover language structure. The packets in the compressed domain can reveal hints as to the phonemes and utterances under the encoding.
(Via Schneier on Security.)
