Editing Null cipher (section)

{{Short description|Simple form of encryption}}
{{About|the classical encryption method|the configuration option in modern communication systems|Null encryption}}
{{more citations needed|date=June 2023}}

A '''null cipher''', also known as '''concealment cipher''', is an ancient form of [[encryption]] where the [[plaintext]] is mixed with a large amount of non-cipher material. Today it is regarded as a simple form of [[steganography]], which can be used to hide ciphertext.<ref name=":0">{{Cite book|title=Official (ISC)2 Guide to the CISSP CBK - Fourth Edition|last=Gordon|first=Adam|publisher=(ISC)2 Press|year=2015|isbn=978-1939572066|pages=349}}</ref>

This is one of three categories of cipher used in [[classical cryptography]] along with [[substitution ciphers]] and [[transposition cipher]]s.<ref name=":2" />