Rubber-hose cryptanalysis

Rubber-hose cryptanalysis is a semi-humorous jargon term used in cryptology for extracting secrets from a person who is part of a cryptosystem by torture, instead of employing a mathematical or technical cryptanalytic attack. (The image is of beatings with a rubber hose, a common form of torture.)

Although the term is flippant, its implications are not: human beings are often the weakest link in a cryptosystem, and torture has been used in real situations in just this way. Many modern cryptosystems and security systems are designed with special emphasis on reducing the amount of human involvement in the keying process to a minimum, so that the threat to both the system and its operators is minimised.