RE: DS Algorithm selection and SHA1 deprecation

[Alex Bligh <alex@alex.org.uk>]

--On 08 December 2005 08:56 -0500 Scott Rose <scottr@nist.gov> wrote:

> If the DS RR is removed, the covering RRSIG wouldn't validate (needs the
> entire RRset).
>
> The validator would get confused and be unable to continue the validation
> chain, but it would be able to know it was under attack.

Yes Geoff just walked in and explained it. There's one RRSig to cover
*all* the digests. I was thinking "but this could be vulnerable to
the SHA-1 attack too". The point, however, is that if ALL parent
zones up to the root have SHA-256, this vulnerability isn't there either.

So I agree that a validator that accepts and SHA-1 digest does not
degrade the security of a signer who signs with SHA-256 and possibly
other digests, assuming SHA-256 is preferred. Which means I also
agree with the proposed text.

Apologies for the rat-hole.

Alex

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