A 286 F2/Cell Distributed Bulk-Current Sensor and Secure Flush Code Eraser Against Laser Fault Injection Attack on Cryptographic Processor

Abstract

Laser fault injection (LFI) attack on cryptographic processors is a serious threat to information security. This paper proposes a sense-and-react countermeasure against LFI. A distributed bulk-current sensor monitors the abnormal current conduction caused by laser irradiation to a silicon substrate. The single sensor occupies only 286 F2/Cell and it is distributed across the entire cryptographic core for 100% attack detection coverage. Upon detection of LFI attack, a flush code eraser prevents a leakage of faulty ciphertext by immediately shunting the core supply path within nano-second order. In addition, the core supply during the shunting is electrically isolated from the global supply line to prevent side-channel information leakage of intermediate faulty codes. A test chip was designed and fabricated in 0.18- $\mu \text{m}$ standard CMOS, integrating a 128-bit Advanced Encryption Standard (AES) cryptographic processor with the proposed countermeasures. A protected AES processor can disable LFI attack with only +28% layout area penalty compared to an unprotected core.