We evaluate our techniques on a standard speech recognition corpus containing over 2,000 phonetically rich phrases spoken by 630 distinct speakers from across the continental United States. Our results indicate that we can identify phrases within encrypted calls with an average accuracy of 50%, and with accuracy greater than 90% for some phrases. Clearly, such an attack calls into question the efficacy of current VoIP encryption standards.
(via Dave Farber’s list).
Combine that fact with this alleged fact:
Several reports have emerged that China is cutting off phone calls mid-sentence when contentious words like ‘protest’ are used.