Re: [AVTCORE] [Cryptex] PR for recommending Cryptex over RFC 6904

A slight wordsmithing:

If one of the peers has advertised both the ability to receive cryptex and the ability to receive header extensions encrypted as per {{RFC6904}} in the SDP exchange, it is RECOMMENDED for the other peer to use Cryptex rather than {{RFC6904}} when sending RTP packets so all the header extensions and CSRCS are encrypted unless there is a compelling reason to use {{RFC6904}} (e.g. a need for some header extensions to be sent in the clear so that so they are processable by RTP middleboxes) in which case, it SHOULD use {{RFC6904}} instead.

I’ve changed “over” to “rather than”; I feel like “over” could be interpreted as applying Cryptex encryption to the 6904 headers, which is clearly not what is intended.

I’ve also added “a” to the beginning of the parenthetical phrase, for grammar reasons.

> On Aug 3, 2022, at 9:33 AM, Bernard Aboba <bernard.aboba@gmail.com> wrote:
> 
> Looks good to me.
> 
>> On Aug 2, 2022, at 23:29, Sergio Garcia Murillo <sergio.garcia.murillo@gmail.com> wrote:
>> 
>> 
>> How about this:
>> 
>> If one of the peers has advertised both the ability to receive cryptex and the ability to receive header extensions encrypted as per {{RFC6904}} in the SDP exchange, it is RECOMMENDED for the other peer to use Cryptex over {{RFC6904}} when sending RTP packets so all the header extensions and CSRCS are encrypted unless there is a compelling reason to use {{RFC6904}} (e.g. need for some header extensions to be sent in the clear so that so they are processable by RTP middleboxes) in which case, it SHOULD use {{RFC6904}} instead.
>> 
>> I don't think we should add the note about checking that the header extensions can be actually sent in clear, as we have put that reason as an example.
>> 
>> What do you think?
>> Sergio
>> 
>> On Tue, Aug 2, 2022 at 6:30 PM Bernard Aboba <bernard.aboba@gmail.com <mailto:bernard.aboba@gmail.com>> wrote:
>> The wording is a bit confusing, because both the Offerer and Answerer can be "sender and receiver" in this context. 
>> 
>> You are trying to give guidance on what a peer should send where the other peer has advertised both the ability to receive cryptex and the ability to receive header extensions encrypted as per RFC 6904. 
>> 
>> The guidance is to send cryptex unless there is a compelling reason to send RFC 6904 (e.g. need for some header extensions in the clear).  However, this only makes sense if the header extensions to be sent in the clear can actually be sent (e.g. if they are sendonly or sendrecv on the sending peer and recvonly or sendrecv on the receiving peer). 
>> 
>> On Tue, Aug 2, 2022 at 2:44 AM Sergio Garcia Murillo <sergio.garcia.murillo@gmail.com <mailto:sergio.garcia.murillo@gmail.com>> wrote:
>> Hi all,
>> 
>> As discussed during the last AVTCORE meeting, I have prepared a PR for adding the recommendation of using Cryptex over RFC6904 adding an exception in the case of some of the header extensions should be sent in clear for RTP middleboxes processing:
>> 
>> If both Cryptex and the Encryption of Header Extensions mechanism defined in {{RFC6904}} are supported by both the sender and receiver, it is RECOMMENDED to use Cryptex over {{RFC6904}} so all the header extensions and CSRCS are encrypted, except when some of the header extensions should be sent in clear so they are processable by RTP middleboxes, in which case, it SHOULD use {{RFC6904}} instead.
>> 
>> https://github.com/juberti/cryptex/pull/111 <https://github.com/juberti/cryptex/pull/111>
>> 
>> Would be great if someone could review the wording as I think it could be simplified.
>> 
>> I will be on vacation from next week, so I will merge the PR and submit a final draft by the end of this week if I don't receive any further feedback on the draft.
>> 
>> Best regards
>> Sergio
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