In cryptography, power analysis is a form of sie channel attack in which the attacker studies the power consumption of a cryptographic hardware device (such as a smart card, tamperproof "black box", microchip, etc). It can yield information about what the device is doing, and including key and other secrets. It was introduced in the open cryptologic community in 1998 by Paul Kocher, Joshua Jaffe and Benjamin Jun, though declassified documents suggest it may have been previously known to the intelligence community. Furthermore, already in 1987 Peter Wright, former MI5 secret service officer and Assistant Director, describes the operation STOCKADE in his book Spycatcher (p. 110-113), which is essentially a power analysis. When Paul Kocher presented his work on the timing attack on networked computers on the sci.crypt news group on 11 Dec. 1995, a 2-week brainstorming followed that revealed the general idea of power analysis and a number of basic countermeasures thereto to a larger audience.