Re: [Gen-art] Gen-ART Telechat Review of draft-ietf-csi-hash-threat-09

[Suresh Krishnan <[e-mail]>]

Hi Pete,
   Thanks for the comments. Please see responses inline.

On 10-03-09 05:32 PM, McCann Peter-A001034 wrote:
> I have been selected as the General Area Review Team (Gen-ART) reviewer
> for this draft (for background on Gen-ART, please see
> http://www.alvestrand.no/ietf/gen/art/gen-art-FAQ.html).
> 
> Please wait for direction from your document shepherd or AD before
> posting a new version of the draft.
> 
> Document: draft-ietf-csi-hash-threat-09
> Reviewer: Pete McCann
> Review Date: 09 March 2010
> IESG Telechat date: 11 March 2010
> 
> Summary:  A couple of minor issues, 
>           and numerous editorial fixes are needed before publication.
> 
> Major issues:  None.
> 
> Minor issues:
> 
> Introduction:
>    There is a great variaty of hash functions, but only MD5 and SHA-1
>    are in the wide use, which is also the case for SEND
> This sentence makes a statement about MD5 and SHA-1 being the only
> widely
> used hash functions, but I can't figure out what it is saying about
> SEND.
> Is it saying that SEND is widely used?  Or did you mean to say that SEND
> implementations typically only implement MD5 and SHA-1?

The latter. I propose changing the text to

"There is a great variety of hash functions, but only MD5 and SHA-1
are widely used. SEND implementations also typically use these two hash 
algorithms."


> 
> Section 3:
>    Supposing that the hash function
>    produces an n-bit long output, since each output is equally likely,
>    an attack takes an order of 2^n operations to be successful.
> SHOULD SAY: "on the order of".  

OK.

> But this sentence is just plain
> incorrect (see below).
>   Due to
>    the birthday attack, if the hash function is supplied with a random
>    input, it returns one of the k equally-likely values, and the number
>    of operations can be reduced to the number of 1.2*2^(n/2) operations.
> There is no "birthday attack."  And I think you meant 2^n instead of k.
> The result you give is due to an equation that is commonly illustrated
> with
> a problem known as the "birthday paradox."

Right. A birthday attack is an attack that exploits the mathematics 
behind the birthday paradox. It is a fairly commonly used term. Would 
you like me to change something?

> 
> Nits/editorial comments:

Agree with you on all these comments. Will fix all these.

Thanks
Suresh