[guardian-dev] The sound of an encrypted audio stream

[Hans-Christoph Steiner]

On 07/24/2013 09:36 PM, Nathan of Guardian wrote:
> On 07/24/2013 09:04 PM, Frank Rieger wrote:
>> The only sensible way to treat this issue is to have a whitelist of allowed codecs that does not include VBR variants.
> 
> I think this is probably a feature we could get into an app like
> CSipSimple fairly easily, and hopefully Jitsi as well.
> 
> At the very least, it could warn users if a VBR codec is enabled, and
> ideally, it could refuse to initiate an encrypted channel.
> 
> Also, @Lee perhaps this could be part of the wizards we have built into
> CSipSimple? Is codec selection one of the values we can build into our
> settings?

I don't know the order of the negotiation, but perhaps the client can be set
up to automatically put all VBR codecs last in the priority list when ZRTP is
configured on that account.  So for example, I have two VoIP accounts on my
CSIP: callcentric and ostel.  callcentric is just classic SIP, everything in
the clear.  VBR is fine there.  ostel is configured with ZRTP, so the VBR
codecs should be used only as a last resort, and perhaps with some kind of
very overt warning, like a TTS voice announcing "using degraded call security!"

.hc

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