A CPLD-Based RC4 Cracking System
Paul D. Kundarewich, Steven J.E. Wilton, Alan J. Hu
Canadian Conference on Electrical and Computer Engineering, 1999
Abstract
This paper presents a CPLD-based system for cracking the RC4 encryption
algorithm. The system achieves outstanding price/performance, easily
beating other low-cost approaches such as commodity PCs.
The system was implemented using a single Altera EPF10K20 Complex
Programmable Logic Device (CPLD)
(currently approx. CAD\$90)
on an Altera UP1 Education Board. This
CPLD is large enough to contain the control unit and five functional
units. Measured performance on our prototype shows that we can crack
32-bit RC4 in 15 hours expected time (30 hours worst case). This gives a
theoretical expected time of 159 days to crack 40-bit keys - the maximum
possible key length that can exported from Canada and the United States.
Our result demonstrates the effectiveness of programmable logic (CPLD or
FPGA) against even a cryptosystem designed for software implementation.
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