Even Smart Cards Can Make Dumb Mistakes
Peter Coffee: Companies should understand the limitations of smart card securityand plan for thembefore counting on smart cards to protect important data.Bits are a lie. The difference between the fiction of bits and the truth of actual hardware is a fundamental threat to secure computing. The software pretense of bits depends on an upstream hardware reality of voltages, currents, stray radio-frequency emissions and other artifacts that our abstract models omitbut that a determined attacker can study and exploit. Its especially important to think about the oft-ignored behaviors of the physical machine if were going to depend on ubiquitous devices such as "smart cards."
Portable, active security tokens have to be built inexpensivelyand have to be compact and lightweightto be useful in their intended applications; the problem is that these attributes often go hand-in-hand with revealing behaviors. Timing attacks, for example, correlate smart card response times against an attackers knowledge of encryption algorithms to dramatically shrink the search space for possible keys. Differential power analysis uses the power consumption patterns of smart card hardware to provide similar clues.