[Spce-user] Can I record SRTP without decryption and ZRTP?

Richard Fuchs rfuchs at sipwise.com
Mon Apr 3 09:59:29 EDT 2017

On 04/02/2017 09:32 PM, Anthony Alba wrote:
> Hi spce users,
> In recording SRTP, both pcap and proc, is it possible to record
> without decryption? (I am "escrowing" SDP elsewhere, so I don't want
> recording-daemon or rtpengine to waste cycles.)
Packets are always decrypted if possible when recording. Currently 
there's no option to turn off decryption when recording.
> User space: pcap - I would like it to store raw SRTP and SRTCP, no
> need for decryption. I presume ZRTP is automatically raw packets??
Correct, ZRTP is transparent through rtpengine and packets are left 
> Kernel space: recording-daemon: who does decryption - kernel module or
> recording daemon? I want to turn off decryption and have recording
> daemon store ciphertext — currently only see options for wav or mp3
Kernel does decryption and recording daemon decodes to wav or mp3. There 
will be an option to have the recording daemon write pcap files as well, 
but these would also contain decrypted packets whenever possible.

The only use case where this makes a difference is SRTP using SDES on 
both sides of the call. In all other cases (SDES only on one side, DTLS, 
etc) packets are always de/encrypted anyway.


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