[Freeswitch-users] Speex + SRTP.. Think again!

[jeff sacksteder]

I don't know if I'd say that, exactly. This is a similar problem to
anonymous remailers. To prevent traffic analysis, you need to
continuously emit equal sized messages of encrypted noise so that you
deny the bad guys information about the time and length of your
messages hidden within.

You could use VBR codecs but you would have to pad the data stream out
to a constant size, nullifing the point of using VBR. You could use
them if compatibility was a concern, for instance. It would not be of
any bandwidth advantage, however.

> This is very interesting.  That rules out ALL VBR codecs when using
> SRTP for security reasons.