Instead of padding all packets to be the same size, two solutions come to mind:<br><br>It would be relatively easy to pad them with shorter random length strings, so that if the average vbr bit rate was n, <br>and the fully padded constant bitrate would be m, we could achieve a bit rate of about (n+m)/2, <br>
which is at least better than m.. <br><br>another option could be to fragment the packets and adjoin them so that they are all about or equal in size.. <br>intertween some creative packets esp. during periods of silence, and that should throw anyone off..<br>
<br>Side channel attacks will always exist, and though scary at first, can usually be engineered around, rather than giving up on the technology..<br><br>-lc<br><br><div class="gmail_quote">On Wed, Jun 11, 2008 at 1:59 PM, jeff sacksteder <<a href="mailto:jsacksteder@gmail.com">jsacksteder@gmail.com</a>> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">I don't know if I'd say that, exactly. This is a similar problem to<br>
anonymous remailers. To prevent traffic analysis, you need to<br>
continuously emit equal sized messages of encrypted noise so that you<br>
deny the bad guys information about the time and length of your<br>
messages hidden within.<br>
<br>
You could use VBR codecs but you would have to pad the data stream out<br>
to a constant size, nullifing the point of using VBR. You could use<br>
them if compatibility was a concern, for instance. It would not be of<br>
any bandwidth advantage, however.<br>
<div class="Ih2E3d"><br>
> This is very interesting. That rules out ALL VBR codecs when using<br>
> SRTP for security reasons.<br>
<br>
</div><div><div></div><div class="Wj3C7c">_______________________________________________<br>
Freeswitch-users mailing list<br>
<a href="mailto:Freeswitch-users@lists.freeswitch.org">Freeswitch-users@lists.freeswitch.org</a><br>
<a href="http://lists.freeswitch.org/mailman/listinfo/freeswitch-users" target="_blank">http://lists.freeswitch.org/mailman/listinfo/freeswitch-users</a><br>
UNSUBSCRIBE:<a href="http://lists.freeswitch.org/mailman/options/freeswitch-users" target="_blank">http://lists.freeswitch.org/mailman/options/freeswitch-users</a><br>
<a href="http://www.freeswitch.org" target="_blank">http://www.freeswitch.org</a><br>
</div></div></blockquote></div><br><br>