Subject: Re: Standardize RSA/SHA256 ?

From: "Hallam-Baker, Phillip" <[email-masked]>
Date: Fri, 12 May 2006 15:57:24 -0700

I can imagine instances where update requests are submitted to automatic verifiers where some sort of exploit is possible.

The weakness inherrent in 1024 bit RSA is a much bigger concern.

 -----Original Message-----
From: 	Mike StJohns [mailto:[email-masked]]
Sent:	Fri May 12 11:12:52 2006
To:	Ben Laurie; Simon Josefsson
Cc:	Dean Anderson; Ólafur Guðmundsson /DNSEXT co-chair; [email-masked]
Subject:	Re: Standardize RSA/SHA256 ?

At 01:43 PM 5/12/2006, Ben Laurie wrote:
> >> Yes, it allows you to produce two things with the same
> >> signature. What is the attack on DNSSEC that arises from this?
> >
> > Wouldn't such a break violate the property of DNSSEC that after
> > successful verification of the digital signature, you know the data
> > you received was the intended published data?
>
>If the publisher of the data chooses to publish stuff which could have
>one of two values for the same signature, then clearly that's what he
>indended.

I think this was sarcasm, but its so hard to tell with Ben.  So lets 
assume not:

If given an SHA1 summary over DNS data (and it's the summary that is 
"signed" not the actual data in DNSSEC), I have a method which lets 
me create a data blob which when summarized will equal that original 
summary, I can substitute my data blob for the DNS data that was 
signed and the recipient can't tell the difference.

Of course, this assumes that the created data blob can be formatted 
in a way that it looks like valid DNS data...

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---

From: Ben Laurie <[email-masked]>
Date: Sat, 13 May 2006 11:37:01 +0100

Hallam-Baker, Phillip wrote:
> I can imagine instances where update requests are submitted to automatic
> verifiers where some sort of exploit is possible.

I can imagine being fabulously wealthy, but it doesn't seem to be
getting me anywhere.

Specify the attack, don't imagine it.

-- 
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"There is no limit to what a man can do or how far he can go if he
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