"Rubber hose key extraction" is a USA idiom representing a beating with a rubber hose with is supposed to be a way to inflict pain without leaving lasting marks

"Rubber hose key extraction" is a USA idiom representing a beating with a rubber hose with is supposed to be a way to inflict pain without leaving lasting marks so it can be used by the authorities to extract information without leaving evidence of the beating - IIRC there are recorded past cases of some sheriff's departments doing this. Other cultures don't bother as much with the aspect of leaving lasting marks. The equivalent Russian language idiom is 'thermorectal cryptanalysis' which involves a soldering iron inserted into the anus and is expected to reveal passwords of any length within a minute.