Designers of secure systems often forget to take information leakage into account. One classic example of this is when the French government designed a mechanism to aid encrypted communications over an analog line, such as at a phone booth. It was a device that clamped onto both ends of the phone, performed the encrypting operations, and sent the signals over the phone line. Unfortunately for the French, the rubber seal that attached the device to the phone was not airtight. It was later discovered that although the encryption itself was solid, if you listened carefully, you could hear the speaker, since the phone was picking up some of the speech! Information leakage can subtly or completely destroy the security of an otherwise bulletproof system.
Generally, only very advanced systems employ defenses against information leakage - there are three main ways to do it:
WIPO ASSIGNS PATENT TO NEC FOR "SENSITIVE INFORMATION LEAKAGE PREVENTION SYSTEM, SENSITIVE INFORMATION LEAKAGE PREVENTION METHOD AND SENSITIVE INFORMATION LEAKAGE PREVENTION PROGRAM" (JAPANESE INVENTOR)
Jul 27, 2011; GENEVA, July 27 -- Publication No. WO/2011/086787 was published on July 21. Title of the invention: "SENSITIVE INFORMATION...
WIPO PUBLISHES PATENT OF NEC FOR "CONFIDENTIAL INFORMATION LEAKAGE PREVENTION SYSTEM, CONFIDENTIAL INFORMATION LEAKAGE PREVENTION METHOD AND CONFIDENTIAL INFORMATION LEAKAGE PREVENTION PROGRAM" (JAPANESE INVENTOR)
Jan 04, 2012; GENEVA, Jan. 4 -- Publication No. WO/2011/162079 was published on Dec. 29, 2011. Title of the invention: "CONFIDENTIAL...