KN-Cipher

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title: "KN-Cipher" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["broken-block-ciphers", "feistel-ciphers"] description: "Block cipher" topic_path: "technology/cryptography" source: "https://en.wikipedia.org/wiki/KN-Cipher" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Block cipher ::

::data[format=table title="Infobox block cipher"]

Field	Value
name	KN-Cipher
designers	Kaisa Nyberg and Lars Knudsen
publish date	1995
key size	198 bits
block size	64 bits
structure	Feistel network
rounds	6
cryptanalysis	Jakobsen & Knudsen's higher order differential cryptanalysis breaks KN-Cipher with only 512 chosen plaintexts and 241 running time, or with 32 chosen plaintexts and 270 running time.
::

| name = KN-Cipher | designers = Kaisa Nyberg and Lars Knudsen | publish date = 1995 | derived from = | derived to = | related to = | certification = | key size = 198 bits | block size = 64 bits | structure = Feistel network | rounds = 6 | cryptanalysis = Jakobsen & Knudsen's higher order differential cryptanalysis breaks KN-Cipher with only 512 chosen plaintexts and 241 running time, or with 32 chosen plaintexts and 270 running time. In cryptography, KN-Cipher is a block cipher created by Kaisa Nyberg and Lars Knudsen in 1995. One of the first ciphers designed to be provably secure against ordinary differential cryptanalysis, KN-Cipher was later broken using higher order differential cryptanalysis.

Presented as "a prototype...compatible with DES", the algorithm has a 64-bit block size and a 6-round Feistel network structure. The round function is based on the cube operation in the finite field GF(233).

The designers did not specify any key schedule for the cipher; they state, "All round keys should be independent, therefore we need at least 198 key bits."

Cryptanalysis

Jakobsen & Knudsen's higher order differential cryptanalysis breaks KN-Cipher with only 512 chosen plaintexts and 241 running time, or with 32 chosen plaintexts and 270 running time.

References

References

1. K. Nyberg, L.R. Knudsen. (1995). "Provable Security Against a Differential Attack". [[Journal of Cryptology]].
2. [[Thomas Jakobsen. (January 1997). "The Interpolation Attack on Block Ciphers". [[Springer-Verlag]].

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::