| Newsgroups |
gmane.mail.spam.srs.general |
| Message-ID |
<[email protected]> |
On Fri, 7 May 2004, Tony Finch wrote:
> On Fri, 7 May 2004 [email protected] wrote:
> > On Thu, 6 May 2004, Seth Goodman wrote:
> > > On Thu, 6 May 2004, Tony Finch wrote:
> > > >
> > > > Note that this simple form of hash is not as safe as you might expect. I'm
> > > > told by a security expert: "MD5 and SHA-1 output an intermediate value of
> > > > their computation from which a hash of the original string plus an
> > > > extension can be calculated. They can therefore not be used safely to
> > > > calculate a MAC as h(key, string), hence HMAC." So we should use RFC2104
> > > > hashes.
> > >
> > > This is big news if it is true. I always thought SHA-1 was suitable for
> > > HMAC's, but I would really like to know if it is not. If what you are
> > > saying is true, isn't it a problem for the existing SRS address format as
> > > well?
> >
> > I am not aware of this weakness. I have also done my research. I would
> > like to see a proper reference for it.
>
> I think there's a bit of miscommunication here. HMAC (described in RFC
> 2104, using either MD5 or SHA1) is the correct way to create the hashes.
> Creating a MAC by simply taking the MD5 or SHA1 of a secret concatenated
> with the public data to be authenticated is not good enough.
>
> RFC 2104 has references that describe why this is the case.
That makes more sense, and I agree with it. The strategy used by SRS does
not suffer these weaknesses.
S.
--
Shevek http://www.anarres.org/
I am the Borg. http://www.gothnicity.org/