[SR-Users] rtpengine - optional srtp

[Daniel-Constantin Mierla]

On 05.09.17 16:08, Richard Fuchs wrote:
> On 09/05/2017 02:32 AM, Daniel-Constantin Mierla wrote:
>> Hello,
>>
>> wondering if anyone has a quick answer to spare some time searching the
>> web or source code -- is there a way to offer optional SRTP (just SDES
>> is also fine) in SDP with RTPEngine? The use case is when the target
>> device is not yet known to support (or not) SRTP.
>>
>> There are couple of ways in specs or practices (e.g., RFC5939/6871, or
>> advertising crypto attributes on RTP/AVP stream, or offering two streams
>> one RTP and one SRTP), I am looking to find if it is possible to do it
>> with RTPEngine and which of the options are supported/what are the
>> parameters for doing it...
>
> That's not currently supported (neither as an offerer nor as an
> accepter). AFAIK the usual mantra is to offer SRTP first and then
> fallback to RTP when a "not supported" (415) is received.
>
> However, it shouldn't be too hard to implement if there's a specific
> use case.
Thanks for the info.

The use case is to do 'best possible' secure communication, in the way
that SRTP is offered, but call should not fail if not supported. Doing
re-routing on 415 could be a solution, however, I met the situation when
the call was accepted but then now audio was heard. It may be a broken
UA after wall.

Anyhow, if it is easy to add and you have some spare time at some point,
it would simplify doing best possible secure session.

Cheers,
Daniel

-- 
Daniel-Constantin Mierla
www.twitter.com/miconda -- www.linkedin.com/in/miconda
Kamailio Advanced Training - www.asipto.com
Kamailio World Conference - www.kamailioworld.com