Phonotactic Reconstruction of Encrypted VoIP Conversations:
Hookt on fon-iks
Abstract—
In this work, we unveil new privacy threats against Voice-over-IP (VoIP)
communications. Although prior work has shown that the interaction of
variable bit-rate codecs and length-preserving stream ciphers leaks
information, we show that the threat is more serious than previously
thought. In particular, we derive *approximate transcripts* of encrypted
VoIP conversations by segmenting an observed packet stream into
subsequences representing individual phonemes and classifying those
subsequences by the phonemes they encode. Drawing on insights from the
computational linguistics and speech recognition communities, we apply
novel techniques for unmasking parts of the conversation. We believe our
ability to do so underscores the importance of designing secure (yet
efficient) ways to protect the confidentiality of VoIP conversations.
http://wwwx.cs.unc.edu/~kzsnow/uploads/8/8/6/2/8862319/foniks-oak11.pdf
My emphasis - I'd love to see some examples... iang
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