Tamper resistance: a cautionary note

An increasing number of systems, from pay-TV to electronic purses, rely on the tamper resistance of smartcards and other security processors. We describe a number of attacks on such systems -- some old, some new and some that are simply little known outside the chip testing community. We conclude that trusting tamper resistance is problematic; smartcards are broken routinely, and even a device that was described by a government signals agency as 'the most secure processor generally available' turns out to be vulnerable. Designers of secure systems should consider the consequences with care.