  WPA2-Personal is widely used to protect Wi-Fi networks against illicit
access. While attackers typically use GPUs to speed up the discovery of weak
network passwords, attacking random passwords is considered to quickly become
infeasible with increasing password length. Professional attackers may thus
turn to commercial high-end FPGA-based cluster solutions to significantly
increase the speed of those attacks. Well known manufacturers such as Elcomsoft
have succeeded in creating world's fastest commercial FPGA-based WPA2 password
recovery system, but since they rely on high-performance FPGAs the costs of
these systems are well beyond the reach of amateurs. In this paper, we present
a highly optimized low-cost FPGA cluster-based WPA-2 Personal password recovery
system that can not only achieve similar performance at a cost affordable by
amateurs, but in comparison our implementation would also be more than 5 times
as fast on the original hardware. Since the currently fastest system is not
only significantly slower but proprietary as well, we believe that we are the
first to present the internals of a highly optimized and fully pipelined FPGA
WPA2 password recovery system. In addition, we evaluated our approach with
respect to performance and power usage and compare it to GPU-based systems. To
assess the real-world impact of our system, we utilized the well known Wigle
Wi-Fi network dataset to conduct a case study within the country and its border
regions. Our results indicate that our system could be used to break into each
of more than 160,000 existing Wi-Fi networks requiring 3 days per network on
our low-cost FPGA cluster in the worst case.
