Analysis of Laser-Based Attack Effects on a Synchronous Circuit

Circuits used in security-related applications must be robust against various types of attacks. One recent and powerful threat is based on the perturbation of the circuit during the application execution. Lasers are the most efficient and precise equipment allowing a hacker to perform such fault-based attacks. Implemented protections are on-line detection mechanisms, often based on error detecting codes to achieve low overheads. Parity-based schemes have in particular been proposed as protections for cryptographic functions, but very few data are available in the open literature about the actual efficiency of such schemes. This paper provides such data, obtained during laser-based attacks on three versions of a synchronous circuit. It is shown that a classical protection technique can leave open doors to an attacker, and that multiple faults must be taken into account when designing the protections. Several other aspects of the effects induced by the laser are discussed in details.