In cryptography, black-bag cryptanalysis is a euphemism for the acquisition of cryptographic secrets via burglary, or other covert means – rather than mathematical or technical cryptanalytic attack. The term refers to the black bag of equipment that a burglar would carry or a black bag operation. As with rubber-hose cryptanalysis, this is technically not a form of cryptanalysis; the term is used sardonically. However, given the free availability of very high strength cryptographic systems, this type of attack is a much more serious threat to most users than mathematical attacks because it is often much easier to attempt to circumvent cryptographic systems (e.g. steal the password) than to attack them directly. Regardless of the technique used, such methods are intended to capture highly sensitive information e.g. cryptographic keys, key-rings, passwords or unencrypted plaintext. The required information is usually copied without removing or destroying it, so capture often takes place without the victim realizing it has occurred. (en)