[Freeswitch-dev] Noise heard when a user holds a conference in SRTP mode

[Ujjwal SIngh]

Hi Brian,
>
>
> I feel that the key exchange is fine in the way the hold is taking place.
>
>                                          (FreeSwitch)
> A                                CONF                IVR
>   |ReINVITE F1(w/o SDP)|                         |
>   |------------------------------->|                         |
>
>   |  200 (with SDP) (K1)  |                         |
>   |<-------------------------------|                         |
>   |     INVITE(K1) F3       |                         |
>   |---------------------------------|----------------------->|
>   |     200 (K2)  F4          |                         |
>
> |<-------------------------------|-------------------------|
>   |     ACK  F5               |                          |
>   |---------------------------------|----------------------->|
>   |     ACK (SDP)(K2) F6 |                         |
>   |-------------------------------->|                        |
>   |                                  |                        |
>   |                                  |                        |
>   |                                  |                        |
>   |                                  |                        |
>                                   (SRTP key K1)      (SRTP key K2)
>
> As you can see in the above call flow :
>
> The local key of conference generated in the offer(200 OK) of the ReINVITE
> is used as the local key by the endpoint for the INVITE sent to MoH, and the
> key generated by the MoH in the answer(200 OK) is used as the key in the
> answer of the ReINVITE(ACK).
>
> I have removed the wireshark trace, the mail wasn't getting through :'(
>
>
> F1 :  (ReINVITE w/o SDP)
>
> F2 :  (200 OK with SDP)        Key K1
>
> F3 :  (INVITE with SDP)          Key K1
>
> F4 :  (200 OK with SDP)        Key K2
>
> F5 :  ACK
>
> F6:  (ACK with SDP)              Key K2
> Please let me know if I am missing something here.
>
> Regards,
> Ujjwal
>
> On Thu, Apr 21, 2011 at 7:38 PM, Brian West <brian at freeswitch.org> wrote:
>
>> Yah SRTP might NEVER work with that method of hold because now the MOH
>> server and the endpoint have to exchange SRTP keys when you refer to them
>> and they probably are NOT doing that right now which is why you get white
>> noise.
>>
>> /b
>>
>> On Apr 21, 2011, at 6:26 AM, Ujjwal SIngh wrote:
>>
>> Yes Brian its a white noise, but the hold method works perfectly fine when
>> used with RTP, the hold is
>>
>> implemented  according to the draft
>>
>> http://datatracker.ietf.org/doc/draft-worley-service-example/?include_text=1
>>
>>
>> Regards,
>> Ujjwal
>>
>>
>>
>>
>> On Thu, Apr 21, 2011 at 3:13 AM, Brian West <brian at freeswitch.org> wrote:
>>
>> I'm going to guess your device method of placing you on hold is wrong.
>>  And
>>
>> possibly doesn't encrypt the data or doesn't signal a key change... is it
>>
>> white noise?
>>
>>
>> /b
>>
>>
>>
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>
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