KHAZAD

Khazad
General
Designers	Vincent Rijmen and Paulo S. L. M. Barreto
First published	2000
Derived from	SHARK
Cipher detail
Key sizes	128 bits
Block sizes	64 bits
Structure	substitution-permutation network
Rounds	8
Best public cryptanalysis
No attack better than on the first five rounds is known.

In cryptography, KHAZAD /xɑːˈzɑːd/ is a block cipher designed by Paulo S. L. M. Barreto together with Vincent Rijmen, one of the designers of the Advanced Encryption Standard (Rijndael). KHAZAD is named after Khazad-dûm, the fictional dwarven realm in the writings of J. R. R. Tolkien (see also Khazad). KHAZAD was presented at the first NESSIE workshop in 2000, and, after some small changes, was selected as a finalist in the project.

KHAZAD has an eight-round substitution-permutation network structure similar to that of SHARK, a forerunner to Rijndael. The design is classed as a "legacy-level" algorithm, with a 64-bit block size (in common with older ciphers such as DES and IDEA) and a 128-bit key. KHAZAD makes heavy use of involutions as subcomponents; this minimises the difference between the algorithms for encryption and decryption.

The authors have stated that, "KHAZAD is not (and will never be) patented. It may be used free of charge for any purpose."

Frédéric Muller has discovered an attack which can break five of KHAZAD's eight rounds. No attacks better than this are known as of August 2009.

References

P. Barreto, V. Rijmen (13–14 November 2000). The Khazad legacy-level block cipher. First open NESSIE Workshop. Leuven. p. 15. Retrieved 2013-01-14.

Alex Biryukov (February 2003). Analysis of Involutional Ciphers: Khazad And Anubis (PDF/PostScript). 10th International Workshop on Fast Software Encryption (FSE '03). Lund: Springer-Verlag. pp. 45–53. Retrieved 2013-01-14.

Frédéric Muller (December 2003). A New Attack against Khazad. Advances in Cryptology - ASIACRYPT 2003. Taipei: Springer-Verlag. pp. 347–358. Retrieved 2013-01-14.

External links

Paulo S. L. M. Barreto (2008-11-19). "The KHAZAD Block Cipher".

Block ciphers (security summary)

Common algorithms	AES Blowfish DES (Internal Mechanics, Triple DES) Serpent Twofish

Less common algorithms	Camellia CAST-128 IDEA RC2 RC5 RC6 SEED ARIA Skipjack TEA XTEA

Other algorithms	3-Way Akelarre Anubis BaseKing BassOmatic BATON BEAR and LION CAST-256 Chiasmus CIKS-1 CIPHERUNICORN-A CIPHERUNICORN-E CLEFIA CMEA Cobra COCONUT98 Crab Cryptomeria/C2 CRYPTON CS-Cipher DEAL DES-X DFC E2 FEAL FEA-M FROG G-DES GOST Grand Cru Hasty Pudding cipher Hierocrypt ICE IDEA NXT Intel Cascade Cipher Iraqi KASUMI KeeLoq KHAZAD Khufu and Khafre KN-Cipher Kuznyechik Ladder-DES Libelle LOKI (97, 89/91) Lucifer M6 M8 MacGuffin Madryga MAGENTA MARS Mercy MESH MISTY1 MMB MULTI2 MultiSwap New Data Seal NewDES Nimbus NOEKEON NUSH PRESENT Prince Q RC6 REDOC Red Pike S-1 SAFER SAVILLE SC2000 SHACAL SHARK Simon SM4 Speck Spectr-H64 Square SXAL/MBAL Threefish Treyfer UES Xenon xmx XXTEA Zodiac

Design	Feistel network Key schedule Lai-Massey scheme Product cipher S-box P-box SPN 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 Timing XSL Interpolation Partitioning Davies' Rebound Weak key Tau Chi-square Time/memory/data tradeoff

Standardization	AES process CRYPTREC NESSIE

Utilization	Initialization vector Mode of operation Padding

Cryptography

History of cryptography Cryptanalysis Outline of cryptography

Symmetric-key algorithm Block cipher Stream cipher Public-key cryptography Cryptographic hash function Message authentication code Random numbers Steganography

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