Engineering Innovation Podcast and Radio Series

Internet Phone Security

PostedJune 29, 2008

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Randy Atkins:  A way to save bandwidth on Internet phone calls is to send digital voice packets…small ones for simple sounds, larger only when they’re complex.  But Charles Wright, of Johns Hopkins, warns that may not be private, even if encrypted.

Charles Wright:  We can learn how the coder decides when to make a big packet or a small packet and we can predict the sequence of sizes that we would see when somebody says a phrase.

Randy Atkins:  In tests, Wright easily deciphered more than half of transmitted phrases by looking at those variations.  But he says there should be fixes.

Charles Wright:  If you can hide that difference somehow, for example, maybe when you’re encrypting them you just make them all the same size.

Randy Atkins:  Wright stresses security needs to be given serious thought now, in early Internet phone development.  With the National Academy of Engineering, Randy Atkins, 103.5 FM, WTOP Radio.