Chasing the Rabbit - a cryptanalytic contest

Erik Zenner ez at
Wed Aug 23 09:26:41 EDT 2006

Hi all!

At the rump session of Crypto 2006, we started the "chasing the Rabbit"
contest. Dan Bernstein was so kind as to present the slides on our
behalf. The details of the contest are given below; they can also be
downloaded from

Best regards

Erik Zenner

Dr. Erik Zenner       Phone:  +45 39 17 96 06    Cryptico A/S
Chief Cryptographer   Mobile: +45 60 77 95 41    Fruebjergvej 3
ez at           DK 2100 Copenhagen


Chasing the Rabbit - a cryptanalytic contest

At the workshop on Fast Software Encryption (FSE) 2003, the stream
cipher Rabbit was presented for the first time. It used a novel approach
for pseudo-random output generation and provided very high performance.
Now, 3 1/2 years later, Rabbit is still unbroken. 

Starting from August 1, 2006, Cryptico A/S starts the Rabbit contest.
The purpose is to encourage further research and analysis, but also the
publication of already existing results. For the most interesting paper
on Rabbit cryptanalysis, Cryptico A/S offers a price of US $ 1000. 

In order to qualify for the competition, a paper has to meet the
following conditions:
- At least part of the paper deals with cryptanalysis of the Rabbit
stream cipher. 
- Cryptanalysis may be of the full cipher, of a reduced version, or of
cipher components. 
- The paper has been accepted for presentation at a cryptographic
conference with fully reviewed proceedings (either online or printed),
or for publication in an academic journal of good standing. 
- Cryptico A/S has been notified about the paper's existence and the
conference or journal it has been accepted for. 

The closing date of the competition is September 30, 2007. After that
date, the Cryptico jury will decide on which paper it considers to be
the most interesting. We preserve the right to split the price money
between several contestants, if this seems most appropriate. 

Closing remarks:
- Employees, former employees, and advisory board members of Cryptico
A/S may not participate. 
- The specification of the Rabbit stream cipher and the white papers on
cryptanalysis are available from the Cryptico homepage,
- For any questions or comments, please contact info at

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