On the vulnerability of FPGA bitstream encryption against power analysis attacks

TLDR

FPGAs are widely used in advanced digital systems, and many models employ bitstream encryption to safeguard intellectual property. The authors aim to demonstrate a side‑channel attack that compromises the bitstream encryption engine of Xilinx Virtex‑II Pro FPGAs. They performed power‑analysis on a single power‑up of the device, coupled with limited offline computation, to recover the triple‑DES keys. The attack successfully recovers all three triple‑DES keys, enabling cloning and manipulation of any Virtex‑II Pro device and exposing further threats such as reverse engineering and hardware Trojans, marking the first reported attack on commercial FPGA bitstream encryption.

Abstract

Over the last two decades FPGAs have become central components for many advanced digital systems, e.g., video signal processing, network routers, data acquisition and military systems. In order to protect the intellectual property and to prevent fraud, e.g., by cloning a design embedded into an FPGA or manipulating its content, many current FPGAs employ a bitstream encryption feature. We develop a successful attack on the bitstream encryption engine integrated in the widespread Virtex-II Pro FPGAs from Xilinx, using side-channel analysis. After measuring the power consumption of a single power-up of the device and a modest amount of off-line computation, we are able to recover all three different keys used by its triple DES module. Our method allows extracting secret keys from any real-world device where the bitstream encryption feature of Virtex-II Pro is enabled. As a consequence, the target product can be cloned and manipulated at the will of the attacker since no side-channel protection was included into the design of the decryption module. Also, more advanced attacks such as reverse engineering or the introduction of hardware Trojans become potential threats. While performing the side-channel attack, we were able to deduce a hypothetical architecture of the hardware encryption engine. To our knowledge, this is the first attack against the bitstream encryption of a commercial FPGA reported in the open literature.