Subject: [CGA-EXT] FW: [Cfrg] Further MD5 breaks: Creating a rogue CA certificate

From: Sean Shen <[email-masked]>
Date: Wed, 31 Dec 2008 10:02:41 +0800

Here is post involving a new attack on hash functions and it started a long
thread of discussions. Please check cfrg or saag for more discussions: 

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of Russ
Housley
Sent: Wednesday, December 31, 2008 12:05 AM
To: [email-masked]; [email-masked]; [email-masked]; [email-masked]
Subject: [Cfrg] Further MD5 breaks: Creating a rogue CA certificate

http://www.win.tue.nl/hashclash/rogue-ca/

MD5 considered harmful today
Creating a rogue CA certificate

December 30, 2008

Alexander Sotirov, Marc Stevens,
Jacob Appelbaum, Arjen Lenstra, David Molnar, Dag Arne Osvik, Benne de Weger

We have identified a vulnerability in the Internet Public Key Infrastructure
(PKI) used to issue digital certificates for secure websites. As a proof of
concept we executed a practical attack scenario and successfully created a
rogue Certification Authority
(CA) certificate trusted by all common web browsers. This certificate allows
us to impersonate any website on the Internet, including banking and
e-commerce sites secured using the HTTPS protocol.

Our attack takes advantage of a weakness in the MD5 cryptographic hash
function that allows the construction of different messages with the same
MD5 hash. This is known as an MD5 "collision". Previous work on MD5
collisions between 2004 and 2007 showed that the use of this hash function
in digital signatures can lead to theoretical attack scenarios. Our current
work proves that at least one attack scenario can be exploited in practice,
thus exposing the security infrastructure of the web to realistic threats.

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