Re: [OSPF] OSPF HMAC Cryptographic Authentication

[Manav Bhatia <[e-mail]>]

Hi Phil,
 
RFC 2104 has the C code that allows the text being hashed to be of an arbitary length; the only restriction imposed is that the length must be a multiple of 8 bits (octet). If you look at draft-eastlake-sha2-02.txt then it allows the text to be hashed to contain an arbitary number of bits.
 
Similarly, the code in RFC 3174 is a "byte-level"implementation. The same draft allows the text to be of an arbitary length. It adds to the RFC 3174 API an additional call,
SHA1FinalBits(), that lets the remaining bits to be added to the hash.

I would prefer to refer to this draft as it (i) has full support for all the SHA2 algorithms and (ii) adds HMAC support for both SHA1 and SHA2 algorithms.
 
Thanks,
Manav

----- Original Message ----
From: Phil Cowburn <[e-mail]>
To: [e-mail]; [e-mail]
Cc: [e-mail]
Sent: Saturday, 22 July, 2006 9:21:44 AM
Subject: Re: [OSPF] OSPF HMAC Cryptographic Authentication


Hi,

In Section 5 you've mentioned the block sizes without units. I presume
they are in bytes, but it would be good if you explicitly state this.

I think it might be good to refer to RFC 3174 somewhere.

Also AFAIK RFC 2104 has the C code to compute HMAC when the text input
is fixed in length. SHA algorithms are defined in terms of variable
number of bits. There may thus be some modifications required in HMAC
C code for SHA. You may want to capture this somewhere.

Otherwise the draft looks in good shape and has been long due. Its
time we all moved away from using MD5 to something thats more
stronger.

Is there a similar work for TCP based protocols like LDP and BGP? Or
other routing protocols like RIP (naah .. am not sure if we really
need something like this for RIP) and i-ISIS (for IP)?

Phil

----- Original Message ----
From: Vishwas Manral <[e-mail]>
To: Rohit Gupta <[e-mail]>
Cc: [e-mail]
Sent: Monday, 17 July, 2006 9:54:59 PM
Subject: Re: [OSPF] OSPF HMAC Cryptographic Authentication


Hi Rohit,

The authors of the OSPF RFC have done it very intelligently. By
allowing the KeyId field which is Opaque, the value of the KeyId
itself defines a seperate security association(channel). IT is the
understanding between the two ends, that a particular KeyId identifies
a key as well as the cryptographic algorithm used.

That is the reason we do not need any new fields.

Thanks,
Vishwas

On 7/17/06, Rohit Gupta <[e-mail]> wrote:
> Hi,
>
> I could not see any new field added in the OSPF message. How do you then make out whether the OSPF router is using HMAC-SHA1 algorithm or the MD5 (the normal OSPF authentication algorithm)?
>
> Thanks,
> Rohit
>
> ----- Original Message ----
> From: Manav Bhatia <[e-mail]>
> To: [e-mail]
> Sent: Saturday, 15 July, 2006 5:06:45 AM
> Subject: [OSPF] OSPF HMAC Cryptographic Authentication
>
>
> Hi,
>
> We have just posted a draft that describes a mechanism for authenticating OSPF packets by making use of HMAC algorithm in conjunction with the SHA family of cryptographic hash functions. It would be great if the WG can provide some feedback and comments on the same.
>
> http://www.ietf.org/internet-drafts/draft-bhatia-manral-white-ospf-hmac-sha-00.txt
>
> Thanks,
> Manav
>
> > ----- Forwarded Message ----
> > From: [e-mail]
> > To: [e-mail]
> > Sent: Saturday, July 15, 2006 1:20:01 AM
> > Subject: I-D ACTION:draft-bhatia-manral-white-ospf-hmac-sha-00.txt
> >
> >
> > A New Internet-Draft is available from the on-line Internet-Drafts
> > directories.
> >
> >
> >    Title        : OSPF HMAC Cryptographic Authentication
> >    Author(s)    : M. Bhatia, et al.
> >    Filename    : draft-bhatia-manral-white-ospf-hmac-sha-00.txt
> >    Pages        : 10
> >    Date        : 2006-6-14
> >
> >   This document describes a mechanism for authenticating OSPF packets
> >   by making use of the HMAC algorithm in conjunction with the SHA
> >   family of cryptographic hash functions. Because of the way the hash
> >   functions are used in HMAC construction, the collision attacks
> >   currently known against SHA-1 do not apply.
> >
> >   This will be done in addition to the already documented
> >   authentication schemes described in the base specification.
> >
> >
> > A URL for this Internet-Draft is:
> > http://www.ietf.org/internet-drafts/draft-bhatia-manral-white-ospf-hmac-sha-00.txt
> >
> > To remove yourself from the I-D Announcement list, send a message to
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