Subject: RE: [OSPF] Revised OSPF HMAC SHA Authentication Draft

From: Manav Bhatia <[email-masked]>
Date: Wed, 23 Aug 2006 09:23:45 +0000 (GMT)

Sujay,
 
OSPF can make use of various cryptographic algorithms in order to authenticate its packets. Your concern is wrt interoperability between disparate implementations where a particular implementation may not implement some certain mandatory-to-implement algorithms. To ensure this doesn’t happen, it is necessary to specify a set of mandatory-to-implement algorithms so that there is at least one algorithm that all implementations will have available. 
 
We cannot assume this mandatory-to-implement algorithm to be MD5, as this has been broken. MD5CRK, was a distributed computing project to break the MD5 hash algorithm in a short period of time. The project closed down with the publication of their paper by Wang, X. et al., "Collisions for Hash Functions MD4, MD5, HAVAL-128 and RIPEMD", August 2004, http://eprint.iacr.org/2004/199  

draft-bhatia-manral-crypto-req-ospf-00.txt defines the current set of mandatory-to-implement algorithms that can be used for the cryptographic authentication for OSPF as well as specifies the algorithms that should/must be implemented because they may get promoted to mandatory at some future time. 
 
http://tools.ietf.org/wg/ospf/draft-bhatia-manral-crypto-req-ospf-00.txt
 
Cheers,
Manav 
________________________________
 From: sujay [mailto:[email-masked]] 
 Sent: Wednesday, August 23, 2006 2:36 PM
 To: 'Manav Bhatia'
 Cc: 'Mailing List'; [email-masked]
 Subject: RE: [OSPF] Revised OSPF HMAC SHA Authentication Draft

 Yes,
 If an authentication fails it could mean the algo's used are different.
 And if one implementation supports MD5 alone( "which I believe is commonly used !" ), the others
 support otherwise, It could be a problem, there is no explicit way we are converying which algo is being used.
 The Au Type = 2 is overloaded.
 Now a "MUST" clause is for the WG to decide.
 Regds,
 Sujay G
 My Location;
 http://maps.google.com/maps?ll=14.626109,76.959229&spn=4.724852,7.525085&t=h&hl=en
 
--
Lucent Technologies

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From: sujay <[email-masked]>
Date: Wed, 23 Aug 2006 16:12:48 +0530

Hi Manav,
Agree, mandatory set of algo is a must.
Which one falls in this set is unsure.
Assuming the requirement of backward compatibility  would still hold good.
I believe the network operators on this list will best mandate the minimal
algo required.
Regds,
Sujay G
My Location;
http://maps.google.com/maps?ll=14.626109,76.959229&spn=4.724852,7.525085&t=h
&hl=en

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-----Original Message-----
From: Manav Bhatia [mailto:[email-masked]] 
Sent: 2006年8月23日 14:54
To: [email-masked]
Cc: [email-masked]; [email-masked]
Subject: RE: [OSPF] Revised OSPF HMAC SHA Authentication Draft

Sujay,
 
OSPF can make use of various cryptographic algorithms in order to
authenticate its packets. Your concern is wrt interoperability between
disparate implementations where a particular implementation may not
implement some certain mandatory-to-implement algorithms. To ensure this
doesn’t happen, it is necessary to specify a set of mandatory-to-implement
algorithms so that there is at least one algorithm that all implementations
will have available. 
 
We cannot assume this mandatory-to-implement algorithm to be MD5, as this
has been broken. MD5CRK, was a distributed computing project to break the
MD5 hash algorithm in a short period of time. The project closed down with
the publication of their paper by Wang, X. et al., "Collisions for Hash
Functions MD4, MD5, HAVAL-128 and RIPEMD", August 2004,
http://eprint.iacr.org/2004/199  

draft-bhatia-manral-crypto-req-ospf-00.txt defines the current set of
mandatory-to-implement algorithms that can be used for the cryptographic
authentication for OSPF as well as specifies the algorithms that should/must
be implemented because they may get promoted to mandatory at some future
time. 

Cheers,
Manav

 Yes,
 If an authentication fails it could mean the algo's used are different.
 And if one implementation supports MD5 alone( "which I believe is commonly
used !" ), the others
 support otherwise, It could be a problem, there is no explicit way we are
converying which algo is being used.
 The Au Type = 2 is overloaded.
 Now a "MUST" clause is for the WG to decide.
 Regds,
 Sujay G
 My Location;
 
http://maps.google.com/maps?ll=14.626109,76.959229&spn=4.724852,7.525085&t=h
&hl=en
 
--
Lucent Technologies