Breaking Ciphers with COPACOBANA - A Cost-Optimized Parallel Code Breaker

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.

[1]  Paul A. Karger,et al.  Security and Privacy Issues in Machine Readable Travel Documents (MRTDs) , 2005 .

[2]  David A. Wagner,et al.  Security and Privacy Issues in E-passports , 2005, First International Conference on Security and Privacy for Emerging Areas in Communications Networks (SECURECOMM'05).

[3]  Philip Heng Wai Leong,et al.  A Smith-Waterman Systolic Cell , 2003, FPL.

[4]  Christof Paar,et al.  Area-time efficient hardware architecture for factoring integers with the elliptic curve method , 2005 .

[5]  Adi Shamir,et al.  A method for obtaining digital signatures and public-key cryptosystems , 1978, CACM.

[6]  Mike Bond,et al.  Experience Using a Low-Cost FPGA Design to Crack DES Keys , 2002, CHES.

[7]  Jean-Didier Legat,et al.  Design Strategies and Modified Descriptions to Optimize Cipher FPGA Implementations: Fast and Compact Results for DES and Triple-DES , 2003, FPL.

[8]  Whitfield Diffie,et al.  Special Feature Exhaustive Cryptanalysis of the NBS Data Encryption Standard , 1977, Computer.

[9]  Matthew J. Weiner,et al.  Efficient DES Key Search , 1994 .

[10]  Manfred Schimmler,et al.  Hardware Enhanced Biosequence Alignment , 2005, METMBS.

[11]  Bruce Schneier,et al.  Minimal Key Lengths for Symmetric Ciphers to Provide Adequate Commercial Security. A Report by an Ad Hoc Group of Cryptographers and Computer Scientists , 1996 .

[12]  William Stallings.  Practical cryptography for data internetworks , 1996 .

[13]  Alfred Menezes,et al.  Guide to Elliptic Curve Cryptography , 2004, Springer Professional Computing.