En lille joke, læs rfc 2410,
http://sunsite.dk/RFC/rfc/rfc2410.html
Citat:
NULL is a block cipher the origins of which appear to be lost in
antiquity. Despite rumors that the National Security Agency
suppressed publication of this algorithm, there is no evidence of
such action on their part. Rather, recent archaeological evidence
suggests that the NULL algorithm was developed in Roman times, as an
exportable alternative to Ceaser ciphers. However, because Roman
numerals lack a symbol for zero, written records of the algorithm's
development were lost to historians for over two millennia.
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Like other modern ciphers, e.g., RC5 [RFC-2040], the NULL encryption
algorithm can make use of keys of varying lengths. However, no
measurable increase in security is afforded by the use of longer key
lengths.