Hot answers tagged voip
I'm not sure which post you're referring to, but one possible source of leakage results from using a variable-bit rate codec. If different sounds compress at different rates, than this will be reflected in the lengths of outgoing encrypted packets. By examining those sequences of lengths, it can sometimes be possible to accurately guess what phrases are ...
Reflex answer: EAX. EAX does encryption and authentication, with minimal space overhead. EAX also has light requirements on the IV: it just needs a non-repeating value, so a simple counter can work. Possibly you already have a suitable counter or time stamp in your packets, that can be used as IV. About replay attacks: you already expect that some packets ...
What about using CTR in that case ? As long as you know the index of the incoming packet you can decrypt it without needing any of the previous or subsequent packets. Do you need integrity as well ?
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