Re: [rtcweb] New use-case proposed

I agree as well since based on our testing for a simple media bridge
that SRTP re-encryption adds a similar amount of CPU load (around 10%). 

Henry

From: rtcweb-bounces@ietf.org [mailto:rtcweb-bounces@ietf.org] On Behalf
Of Roman Shpount
Sent: May-11-12 12:26 PM
To: Harald Alvestrand
Cc: rtcweb@ietf.org
Subject: Re: [rtcweb] New use-case proposed

+1

I have provided the CPU requirements for doing SRTP re-encryption
before. Bottom line, on the real conferencing service encryption adds
about 10% extra CPU load. There is no benefit in compromising security
to avoid re-encrypting.
_____________
Roman Shpount

On Fri, May 11, 2012 at 12:21 PM, Harald Alvestrand
<harald@alvestrand.no> wrote:

I propose to reject this use case because it requires yet another
security redesign.
The clue is here:

- The keying solution must allow each participants to encrypt to
multiple receivers without any decryption+encryption in the middle node

This means that each participant must use the same encryption keys to
all other participants; this in turn means that when someone leaves the
group, all participants must change their encryption keys; it also means
that as long as shared keys are used for authentication, all
participants can impersonate all other participants.

In fact, this solution has most of the issues (except for the network
layer deployment issue) that leads me to strongly advocate leaving
multicast out of scope for this effort.

              Harald

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