Editing Zeroisation (section)

==Mechanical==
When [[encryption]] was performed by [[rotor machine|mechanical devices]], this would often mean changing all the machine's settings to some fixed, meaningless value, such as [[0 (number)|zero]]. On machines with letter settings rather than [[Numerical digit|numerals]], the letter 'O' was often used instead. Some machines had a button or lever for performing this process in a single step. Zeroisation would typically be performed at the end of an encryption session to prevent accidental disclosure of the keys, or immediately when there was a risk of capture by an adversary.<ref>[https://web.archive.org/web/20120926071443/http://www.dtic.mil/cjcs_directives/cdata/unlimit/m652001.pdf Link 16 Joint Key Management Plan, CJCSM 6520.01A, 2011, Section 6b(4)(b)]</ref>