KN-Cipher
General
Designers	Kaisa Nyberg and Lars Knudsen
First published	1995
Cipher detail
Key sizes	198 bits
Block sizes	64 bits
Structure	Feistel network
Rounds	6
Best public 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.^[1]

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."^[2]

References

^ ^a ^b T. Jakobsen, L.R. Knudsen (January 1997). The Interpolation Attack on Block Ciphers (PDF/PostScript). 4th International Workshop on Fast Software Encryption (FSE '97). Haifa: Springer-Verlag. pp. 28–40. Retrieved 23 January 2007.
^ K. Nyberg, L.R. Knudsen (1995). "Provable Security Against a Differential Attack" (PDF/PostScript). Journal of Cryptology. 8 (1): 27–37. doi:10.1007/bf00204800. ISSN 0933-2790. S2CID 11867695. Retrieved 23 January 2007.

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Design	Feistel network Key schedule Lai–Massey scheme Product cipher S-box P-box SPN Confusion and diffusion Round Avalanche effect Block size Key size Key whitening (Whitening transformation)
Attack (cryptanalysis)	Brute-force (EFF DES cracker) MITM Biclique attack 3-subset MITM attack Linear (Piling-up lemma) Differential Impossible Truncated Higher-order Differential-linear Distinguishing (Known-key) Integral/Square Boomerang Mod n Related-key Slide Rotational Side-channel Timing Power-monitoring Electromagnetic Acoustic Differential-fault XSL Interpolation Partitioning Rubber-hose Black-bag Davies Rebound Weak key Tau Chi-square Time/memory/data tradeoff
Standardization	AES process CRYPTREC NESSIE
Utilization	Initialization vector Mode of operation Padding

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Category

Cryptanalysis

References