Abstract
Cryptanalysis of symmetric and asymmetric ciphers is computationally extremely demanding. Since the security parameters (in particular the key length) 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 (assuming no mathematical breakthrough) 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 presents the design and realization of the COPACOBANA (Cost-Optimized Parallel Code Breaker) machine, which is optimized for running cryptanalytical algorithms and can be realized for less than US$ 10,000. It will be shown that, depending on the actual algorithm, the architecture can outperform conventional computers by several orders in magnitude. COPACOBANA hosts 120 low-cost FPGAs and is able to, e.g., perform an exhaustive key search of the Data Encryption Standard (DES) in less than nine days on average. As a real-world application, our architecture can be used to attack machine readable travel documents (ePass). COPACOBANA is intended, but not necessarily restricted to solving problems related to cryptanalysis.
The hardware architecture 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. Even though breaking full-size RSA (1024 bit or more) or elliptic curves (ECC with 160 bit or more) is out of reach with COPACOBANA, it can be used to analyze cryptosystems with a (deliberately chosen) small bitlength to provide reliable security estimates of RSA and ECC by extrapolation.
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Keywords
- Elliptic Curve
- Discrete Logarithm Problem
- International Civil Aviation Organization
- Data Encryption Standard
- Elliptic Curve Cryptosystems
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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Kumar, S., Paar, C., Pelzl, J., Pfeiffer, G., Schimmler, M. (2006). Breaking Ciphers with COPACOBANA –A Cost-Optimized Parallel Code Breaker. In: Goubin, L., Matsui, M. (eds) Cryptographic Hardware and Embedded Systems - CHES 2006. CHES 2006. Lecture Notes in Computer Science, vol 4249. Springer, Berlin, Heidelberg. https://doi.org/10.1007/11894063_9
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