Forwarded From: "Jay D. Dyson" <jdyson@techreports.jpl.nasa.gov>
Forwarded From: Frank Andrew Stevenson <frank@funcom.com>
Posted To: cryptography@c2.net
After over 1 year of preperation the keyblitz project realeased it's DES
searching client on May 1st this year, the search was only allowed to run
for 11 days before it faced a possible legal challenge:
http://www.thoic.com/keyblitz/
The keyblitz search is not a academic DES challenge, but a real life
'malicious' attack on a deployed cryptographic system. The target of the
search is management keys for the European D2-MAC / Eurocrypt sattelite
scrambling system.
Although the search had only been running for 11 days the team claimed to
have recovered 2 DES keys already. This is made possible by exploiting a
weakness in the Eurocrypt protocoll. TV signals are coded under the
control of a single Operational key. However this key is continously being
updated to the systems smart cards encrypted under as many as perhaps 2000
different managment keys. Recovering a single managment key will suffice
to recover future operational keys.
The modified DES search will encrypt the known operational (plaintext) key
with a set of trial keys, and check every encryption against the list of
2000 ciphertexts. Such a lookup is much faster that 2000 trial
encryptions, and can be done quickly using binary search or table lookups.
The net result is that the complexity of recovering a single management
key is 2^45 as opposed to 2^55 of recovering a single DES key.
Subsequent operational keys can then be found by simple decryption, and
published over the internet on such sites as http://www.d2mac.com
frank
- --
This sentence is unique in this respect;
it can safely be attributed to my employer, Funcom productions.
E3D2BCADBEF8C82F A5891D2B6730EA1B PGPencrypted mail preferred, finger for key
There is no place like N59 50.558' E010 50.870'.
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-o-
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Received on Wed May 13 14:32:55 1998