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[Full-Disclosure] Re: Re-write with security in mind all ops.
From: Feher Tamas (etomcatfreemail.hu)
Date: Mon Aug 23 2004 - 13:41:34 CDT
>It wouldn't be that hard, just no unencrypted traffic
>and no unencrypted interprocess communication.
>Spammers and bozos would have to work a lot harder
Except for important crypto was broken... nothing is safe:
"Opinion: Cryptanalysis of MD5 and SHA: Time for a new standard
by Bruce Schneier, Counterpane, 19 Aug 2004
Crypto researchers report weaknesses in common hash functions
At the Crypto 2004 conference in Santa Barbara, Calif., this
researchers announced several weaknesses in common hash
These results, while mathematically significant, aren't
alarm. But even so, it's probably time for the cryptography
to get together and create a new hash standard.
One-way hash functions are a cryptographic construct used in
applications. They are used with public-key algorithms for both
encryption and digital signatures. They are used in
They are used in authentication. They have all sorts of
a great many different protocols. Much more than encryption
one-way hash functions are the workhorses of modern
In 1990, Ron Rivest invented the hash function MD4. In 1992, he
improved on MD4 and developed another hash function: MD5. In
National Security Agency published a hash function very
similar to MD5,
called the Secure Hash Algorithm (SHA). Then in 1995, citing
discovered weakness that it refused to elaborate on, the NSA
change to SHA. The new algorithm was called SHA-1. Today,
popular hash function is SHA-1, with MD5 still being used in
One-way hash functions are supposed to have two properties. One,
they're one-way. This means that it's easy to take a message and
compute the hash value, but it's impossible to take a hash
value and re-
create the original message. (By "impossible," I mean "can't
be done in
any reasonable amount of time.") Two, they're
means that it's impossible to find two messages that hash to
hash value. The cryptographic reasoning behind these two
subtle, and I invite curious readers to learn more in my
Breaking a hash function means showing that either -- or
both -- of
those properties aren't true. Cryptanalysis of the MD4
family of hash
functions has proceeded in fits and starts over the past
decade or so,
with results against simplified versions of the algorithms
results against the whole algorithms.
This year, Eli Biham and Rafi Chen, and separately Antoine Joux,
announced some pretty impressive cryptographic results
against MD5 and
SHA. Collisions have been demonstrated in SHA. And there are
unconfirmed at this writing, of results against SHA-1.
The magnitude of these results depends on who you are. If
cryptographer, this is a huge deal. While not revolutionary,
results are substantial advances in the field. The
by the researchers are likely to have other applications,
and we'll be
better able to design secure systems as a result. This is
science of cryptography advances: We learn how to design new
by breaking other algorithms. In addition, algorithms from
the NSA are
considered a sort of alien technology: They come from a
with no explanations. Any successful cryptanalysis against
algorithm is an interesting data point in the eternal
question of how
good they really are in there.
As a user of cryptographic systems -- as I assume most
readers are --
this news is important, but not particularly worrisome. MD5
aren't suddenly insecure. No one is going to be breaking digital
signatures or reading encrypted messages anytime soon with these
techniques. The electronic world is no less secure after these
announcements than it was before.
But there's an old saying inside the NSA: "Attacks always
they never get worse." These techniques will continue to
probably someday there will be practical attacks based on these
It's time for us all to migrate away from SHA-1.
Luckily, there are alternatives. The National Institute of
and Technology (NIST) already has standards for longer --and
break -- hash functions: SHA-224, SHA-256, SHA-384 and
already government standards and can already be used. This
is a good
stopgap, but I'd like to see more.
I'd like to see NIST orchestrate a worldwide competition for
a new hash
function, like it did for the new encryption algorithm, Advanced
Encryption Standard, to replace Data Encryption Standard.
issue a call for algorithms and conduct a series of analysis
where the community analyzes the various proposals with the
establishing a new standard.
Most of the hash functions we have and all the ones in
are based on the general principles of MD4. Clearly we've
learned a lot
about hash functions in the past decade, and I think we can
applying that knowledge to create something even more secure.
Better to do it now, when there's no reason to panic, than
now, when there might be."
Full-Disclosure - We believe in it.