Subject: [rohc] sigcomp - state_identifier matching an existing one at a STATE-CREATE

From: Cristian CONSTANTIN <[email-masked]>
Date: Sun, 15 May 2005 00:43:20 +0200

hi!

suppose that a STATE-CREATE tries to create a state with a
state_identifier that matches (taking into account the
minimum_access_length) another state which already exists in the same
compartment.

what should happen?

1. create a new state (even though the state_identifiers will overlap)
2. drop the old one?
3. drop the new one?

bye now!
cristian
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---

From: "Surtees, Abigail" <[email-masked]>
Date: Tue, 17 May 2005 12:09:15 +0100

Hi Cristian,  

Apologies, I seem to be confusing things rather than clarifying.
There's an extra 'not' in what I wrote.
> 
> However, according to Paul Hoffman and Bruce Schneier's draft 
> on the subject 
(<http://www.ietf.org/internet-drafts/draft-hoffman-hash-attacks-03.txt>
), it is not the >'collision free' property of the SHA-1 that has been
attacked rather than the 'one way' 
>property.  The above attack would require the 'one way' property to be
broken, so the 
>weaknesses discovered do not affect the vulnerability of SigComp.

It should say:

It *is* the collision free property that has been attacked and not the
'one way' property.    

The conclusion remains the same - SigComp is no more vulnerable than it
was before this weaknesses were found.

Best regards,

Abbie

Abbie Surtees
Senior Engineer
Roke Manor Research Ltd
Old Salisbury Lane
Romsey, SO51 0ZN
Tel:   +44 (0) 1794 833131