RE: Optional SRTP with SDES?

["Wayne Mills \(wmills\)" <wmills@xxxxxxxxx>]

I think Mark's comments were more aimed at your parenthetical ("in
principle anyway").  Sdescriptions has syntax (e.g. "unencrypted_srtp")
to alter a crypto suite so that authentication is still enabled while
encryption is disabled, so it accomodates establishment of unencrypted
SRTP ( oxymoronic as that sounds :) ).

Back to syntax, I think "a=security: <optional|mandatory>" is better
than "a=encryption: <optional|mandatory>", due to the ability to
negotiate unencrypted SRTP.

Regards,
Wayne

> >>>
> >>> 2) Add an encryption attribute (e.g.
> >>> "a=encryption=<optional|mandatory>").
> >>
> >> I agree that adding something explicit like this would be good.   
> >> But I have a nit here: we probably want to choose a term 
> other than 
> >> "encryption", since SRTP can provide authentication and not 
> >> encryption (in principle anyway - the sdesc spec doesn't 
> include any 
> >> cryptosuites that do authentication but not encryption, IIRC).
> >
> > Any sdescriptions crypto suite can signal 
> "unencrypted_srtp", which is 
> > effectively SRTP null encryption.
> >
> > Mark
> 
> Sure, but SRTP with NULL encryption is not equivalent to RTP 
> - turning off encryption is not the same as not doing SRTP.  
> If I understand Rick correctly, this is why he's suggesting 
> the additional "a=encryption" attribute.
> 
> David
> 
> 
> >> Maybe "a=secure" would be better.
> >>
> >>>