Abstract:
Cryptanalysis of symmetric and asymmetric ciphers is 
computationally extremely demanding. Since the security 
parameters of almost all practical crypto algorithms are 
chosen such that attacks with conventional computers are 
computationally infeasible, the only promising way to 
tackle existing ciphers (in the absence of mathematical
breakthroughs) is to build special-purpose hardware. 
Dedicating those machines to the task of cryptanalysis 
holds the promise of a dramatically improved cost-
performance ratio so that breaking of commercial ciphers 
comes within reach. 

This contribution describes the design and realization of 
the reprogrammable machine COPACOBANA (Cost-Optimized 
Parallel Code Breaker), which is optimized for running 
cryptanalytical algorithms. The primary design goal was 
to produce a re-program\-mable low-cost design for less than 
Euro 10,000 which is applicable for attacking the Data 
Encryption Standard (DES) in less than nine days. 

It will be shown that the architecture outperforms 
conventional computers by several orders of magnitude. 
Fully configured, COPACOBANA can host 120 low-cost FPGAs. 
In this configuration, the COPACOBANA hardware is able to 
perform an exhaustive key search of DES at a rate of more 
than 2^{35} keys per second, yielding an average search time 
of less than nine days. For this, we used the high-speed DES 
engine design of the Universite Catholique de Louvain's 
Crypto Group.

We provide a real-world example by giving an estimate of an 
attack with COPACOBANA against a formerly popular encryption 
tool (Norton Diskreet). Due to a cryptographical weak key 
derivation function it can be broken in very little time by 
applying a smart key search.

COPACOBANA is suitable for computational problems which are 
parallelizable and have low communication requirements. 
The hardware can be used, e.g., to attack elliptic curve 
cryptosystems and to factor numbers. COPACOBANA is intended 
to, but not necessarily restricted to solving problems related 
to cryptanalysis.


BibTeX:
@InProceedings{I-KPPPRS06,
  author =	 {S. Kumar and C. Paar and J. Pelzl and G. Pfeiffer
                  and A. Rupp and M. Schimmler},
  title =	 "{How to Break DES for \geneuronarrow{}~8,980}",
  booktitle =	 "{International Workshop on Special-Purpose Hardware
                  for Attacking Cryptographic Systems --- SHARCS'06,
                  Cologne, Germany}",
  year =	 {2006},
  address =	 {\url{http://www.sharcs.org}},
  month =	 {April}
}