[10322] in cryptography@c2.net mail archive
Re: Cringely Gives KnowNow Some Unbelievable Free Press... (fwd)
daemon@ATHENA.MIT.EDU (Eric Rescorla)
Tue Jan 29 16:38:06 2002
To: Ben Laurie <ben@algroup.co.uk>
Cc: Cryptography List <cryptography@wasabisystems.com>
Reply-To: EKR <ekr@rtfm.com>
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From: Eric Rescorla <ekr@rtfm.com>
Date: 29 Jan 2002 07:38:14 -0800
In-Reply-To: Ben Laurie's message of "Tue, 29 Jan 2002 15:26:40 +0000"
Message-ID: <kj1yg9qiah.fsf@romeo.rtfm.com>
Ben Laurie <ben@algroup.co.uk> writes:
> Eric Rescorla wrote:
> > I don't know exactly what Pegwit does, but most of these schemes
> > are still vulnerable to dictionary attacks by trying arbitrary
> > passphrases and seeing if they generate the correct public key.
> > It's of course slower since the test operation is slower.
>
> If you want to slow down test operations, then iteration is good.
I agree.
> BTW, I don't see why using a passphrase to a key makes you vulnerable to
> a dictionary attack (like, you really are going to have a dictionary of
> all possible 1024 bit keys crossed with all the possible passphrases?
> Sure!).
Unfortunately, "dictionary attack" is used differently by different
people. There are two different kinds of attacks here:
(1) A brute-force attack such as is used by Crack where you
successively try a small subset of the passphrase space in
the expectation that it is the space that people are likely
to populate. (This is what RFC 2828 calls a dictionary attack).
(2) A table-driven attack where you have an enormous table
(say of passphrases to keys) and just do a lookup in the table.
I was referring to the former, which is quite practical against
such a system. The latter probably consumes too much memory to
be practical.
-Ekr
--
[Eric Rescorla ekr@rtfm.com]
http://www.rtfm.com/
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