Re: [AVTCORE] Registering AVP Profiles for RTP over QUIC

[Roman Shpount <[e-mail]>]

Hi Spencer,

I was thinking not about using QUIC to transport RTP, just to negotiate the
encryption keys and protocol. Once keys and protocol are negotiated,
SRTP-over-UDP sends the packets. SRTP/SRTCP packets are demultiplexed from
QUIC, and both protocols run side-by-side. This means none of the QUIC
encryption, NACK, congestion control, etc., is used for media. It is an
exact equivalent of DTLS-SRTP with QUIC being used instead of DTLS to
negotiate keys.

Even if this draft does not cover such a set-up, I think it is a viable
network configuration. Whatever protocol name you will come up with, it
should be possible to differentiate media over QUIC vs. key negotiation
over QUIC.
_____________
Roman Shpount


On Wed, May 11, 2022 at 6:41 PM Spencer Dawkins at IETF <
[e-mail]> wrote:

> Hi, Roman,
>
> On Wed, May 11, 2022 at 4:12 PM Roman Shpount <[e-mail]> wrote:
>
>> What about using QUIC for encryption session setup and SRTP for sending
>> media, similar to DTLS-SRTP? This can be the easiest option to implement.
>>
>
> I'm not aware of a way to stop encryption in RFC 9000 QUIC, which is using
> RFC 9001 TLS for key exchange, etc, in favor of an application-level
> encryption mechanism. This has come up a number of times in conversations
> with 3GPP, who also wanted to avoid duplicate encryption (details don't
> matter, at this point), and the IETF has always said they wouldn't provide
> that.
>
> But maybe something has changed?
>
> Best,
>
> Spencer
>
>
>> Best,
>> _____________
>> Roman Shpount
>>
>>
>> On Wed, May 11, 2022 at 4:47 PM Spencer Dawkins at IETF <
>> [e-mail]> wrote:
>>
>>> Dear AVTCORE,
>>>
>>> I've had an open PR in
>>> https://github.com/SpencerDawkins/sdp-rtp-quic/pull/9 for a while,so I
>>> could get a sense of how AVT profiles are supposed to work, and I'd like to
>>> push on that now (with a virtual interim meeting coming up next week)..
>>>
>>> The high-level summary of discussion in
>>> https://github.com/SpencerDawkins/sdp-rtp-quic-issues/issues/5 (note
>>> that this discussion is in a different repo, because reasons) has been
>>> roughly,"what's the difference between QUIC/RTP/AVPF and QUIC/RTP/SAVPF"?
>>>
>>> The arguments about not registering secure AVP profiles involve
>>>
>>>    -  the computational overhead of double encryption for all packets,
>>>    plus
>>>    - the payload overhead of 10 bytes per packet since you have 2 HMACs.
>>>
>>> The arguments about registering secure AVP profiles seem to revolve
>>> around
>>>
>>>    - Minimizing the impact of added QUIC support in existing
>>>    implementations that are using /RTP/SAVPF now.
>>>    - QUIC encryption protects payloads between QUIC endpoints, but
>>>    there are many multi-endpoint RTP topologies (
>>>    https://www.rfc-editor.org/rfc/rfc7667 has about 50 pages of them),
>>>    and when a middlebox receives  QUIC/RTP/AVPF, it's not obvious whether the
>>>    middlebox should
>>>       - forward the RTP payload using  RTP/AVPF (where the outgoing
>>>       AVPF matches the incoming AVPF), or
>>>       - forward the RTP payload using RTP/SAVPF, where the outgoing
>>>       SRTP encryption matches the incoming QUIC
>>>
>>> It seems to me that there are three choices:
>>>
>>>    - Use only QUIC/RTP/AVPF, and and require middleboxes receiving
>>>    QUIC/RTP/AVPF traffic to always forward that traffic over RTP/SAVPF
>>>    - Use only QUIC/RTP/AVPF, and and require senders to signal
>>>    middleboxes whether they should forward that traffic over RTP/AVPF or
>>>    RTP/SAVPF
>>>    - Register both QUIC/RTP/AVPF and QUIC/RTP/SAVPF, and if you have to
>>>    do double encryption on the QUIC/RTP paths to get RTP/SAVPF on the other
>>>    side of a middlebox, too bad
>>>
>>> So, my questions are,
>>>
>>>    - What am I missing here?
>>>    - Are any of the choices I'm listing obviously the *BEST* choice?
>>>
>>> Best,
>>>
>>> Spencer
>>> _______________________________________________
>>> Audio/Video Transport Core Maintenance
>>> [e-mail]
>>> https://www.ietf.org/mailman/listinfo/avt
>>>
>>