[918] in cryptography@c2.net mail archive
Re: DES cracking is making real progress
daemon@ATHENA.MIT.EDU (Jyri Kaljundi)
Thu May 29 18:02:10 1997
Date: Fri, 30 May 1997 00:04:50 +0300 (EET DST)
From: Jyri Kaljundi <jk@stallion.ee>
To: Phil Karn <karn@qualcomm.com>
cc: frantz@netcom.com, cryptography@c2.net
In-Reply-To: <199705290755.AAA26405@servo.qualcomm.com>
On Thu, 29 May 1997, Phil Karn wrote:
> This is a *very* good point. I don't know Wells Fargo's system, but I
> do use Bank of America's -- and this attack would definitely succeed
> there. On the other hand, their web banking service doesn't let you
> write arbitrary checks.
Here in Estonia the largest bank was using a system in their telebanking
(both modem and Internet) service, where all the data between the client
and server was encrypted using IDEA 128-bit keys, that's strong, isn't it.
The bad thing was that both ends were supposed to use the same session
encryption key, but the session key was never sent over the channel
according to the bank. That meant that both ends had someone know the
session key. The only thing that the bank user had to enter when beginning
the session was their 6-digit one-time password (actually even worse, it
was number from 1 to 999999). So what they did was probably
IDEAkey=3Dmd5hash(password) so they got 128-bit key from 6-digit number
(should be 2^20 or so).=20
When the scandal broke up, the bank said they were using "specific
cryptographic methods" for generating the 128-bit key, but they would not
tell what these methods were. But they were secure so they said. And the
Windows clients were freely available on the web for everyone to
decompile. Of course there has not been any public review of the code and
they have nobody there who would really know about cryptography.
And there was an option for clients to choose if they want to use one-time
passwords or use the same password all the time ...
And there was no authentication being done, meaning it was wide open for
all kind of MITM and other attacks ...
Yes now they have changed the code, but they still won't tell what they
are using there (they say there are digital signatures deep inside the
code somewhere now). But they say it's so secure without telling anyone.
Did I say this is the largest bank in Baltics? Like I have said, life is
fun around here.=20
J=FCri
