There was an interesting article this last Friday at the New Scientist about how the contents of encrypted VOIP conversations could still be deduced via traffic analysis. The short version is that many spoken words have a signature to them even when they are encrypted. This signature is related to the size of the data packets used to represent the sound data. Many phonemes in a word have a distinct encoded data size… by analyzing the packet sizes you can deduce the phonemes and thus the spoken word.
This got me thinking I should write about the complex problem of securing a video stream. There are many aspects to securing a video stream: integrity, authenticity, and privacy being the most important. I’m not going to spend time talking about integrity and authenticity, because those are somewhat simpler problems to solve (integritiy = digital signatures, authenticity = digital certificates). The main focus of this post is about privacy; keeping an eavesdropper from deducing the contents of a video stream.
