Breaking Hitag 2 Revisited

Abstract

Many Radio Frequency IDentification (RFID) applications such as car immobilizers and access control systems make use of the proprietary stream cipher Hitag 2 from the company NXP. Previous analysis has shown that the cipher is vulnerable to different attacks due to the low complexity of the cipher and its short 48-bit secret key. However, all these attacks either rely on expensive reconfigurable hardware, namely the Field Programmable Gate Array (FPGA) cluster COPACOBANA, or are impractical. In this paper we develop the first bit-sliced OpenCL implementation for the exhaustive key search of Hitag 2 that runs on off-the-shelf hardware. Our implementation is able to reveal the secret key of a Hitag 2 transponder in less than 11 hours on a single Tesla C2050 card in the worst case. The speed of our approach can be further improved due to its scalability, i.e., we estimate a speed of less than one hour on a heterogeneous platform cluster consisting of CPUs and GPUs that can be realized with a budget of less than 5,000 €. This result enables anyone to obtain the secret key with only two sniffed communications in shorter time and with significantly less cost compared to systems such as the COPACOBANA.