Re: [P2PSIP] HIP vs. TLS/DTLS/SRTP (was HIP pros and cons)

[Miika Komu <[e-mail]>]

On Tue, 18 Dec 2007, Eric Rescorla wrote:

> At Mon, 17 Dec 2007 17:30:24 -0500,
> Philip Matthews wrote:
>> In all three proposals, media packets would flow directly between the
>> X and Y, and not hop-by-hop around the overlay. So when ESP was used,
>> there would be no need to use STRP for media, or TLS or DTLS for
>> signaling.
>
> This is arguably a bug, not a feature.
>
> SRTP was explicitly designed to have very low overhead: just the
> bits of the authentication tag itself, with no header, etc. The
> rationale for this design was that RTP packets tend to be very
> small and so the overhead for the header, IV, etc. was significant.
> In cases where that type of constraint applies, then wrapping the
> RTP in ESP would be bad.

I think the difference is around 18 bytes:

http://dasan.sejong.ac.kr/~wisa04/ppt/1A1.ppt

In practice, the difference is insignificant according to these results:

Bilien et at: Secure VoIP: call establishment and media protection:
http://www.minisip.org/publications/secvoip-minisip-camera.pdf

Currently, all three (public) HIP implementations support BEET-mode-ESP by 
default. It has exactly the same byte overhead as transport mode.

-- 
Miika Komu                                       http://www.iki.fi/miika/

_______________________________________________
P2PSIP mailing list
[e-mail]
https://www1.ietf.org/mailman/listinfo/p2psip