DFC (cipher)

From Wikipedia, the free encyclopedia

DFC
General
Designers	Jacques Stern, Serge Vaudenay, et al.
First published	1998
Related to	COCONUT98
Cipher detail
Key sizes	128, 192, or 256 bits
Block sizes	128 bits
Structure	Feistel network
Rounds	8
Best public cryptanalysis
Knudsen and Rijmen's differential attack breaks 6 rounds

In cryptography, DFC (Decorrelated Fast Cipher) is a symmetric block cipher which was created in 1998 by a group of researchers from École Normale Supérieure, CNRS, and France Télécom (including Jacques Stern and Serge Vaudenay) and submitted to the AES competition.

Like other AES candidates, DFC operates on blocks of 128 bits, using a key of 128, 192, or 256 bits. It uses an 8-round Feistel network. The round function uses a single 6×32-bit S-box, as well as an affine transformation mod 2⁶⁴+13. DFC can actually use a key of any size up to 256 bits; the key schedule uses another 4-round Feistel network to generate a 1024-bit "expanded key". The arbitrary constants, including all entries of the S-box, are derived using the binary expansion of e as a source of "nothing up my sleeve numbers".

Soon after DFC's publication, Ian Harvey raised the concern that reduction modulo a 65-bit number was beyond the native capabilities of most platforms, and that careful implementation would be required to protect against side-channel attacks, especially timing attacks. Although DFC was designed using Vaudenay's decorrelation theory to be provably secure against ordinary differential and linear cryptanalysis, in 1999 Lars Knudsen and Vincent Rijmen presented a differential chosen-ciphertext attack that breaks 6 rounds faster than exhaustive search.

In 2000, Vaudenay, et al. presented an updated version of the algorithm, called DFCv2. This variant allows for more choice in the cipher's parameters, and uses a modified key schedule to eliminate certain weak keys discovered by Don Coppersmith.

References

H. Gilbert, M. Girault, P. Hoogvorst, F. Noilhan, T. Pornin, G. Poupard, J. Stern, S. Vaudenay (19 May 1998). Decorrelated Fast Cipher: an AES candidate (PDF/PostScript). Retrieved 8 February 2007.
Harvey, Ian (March 1999). "The DFC Cipher: An Attack on Careless Implementations" (PDF). Second AES Candidate Conference. Retrieved 21 January 2009.
Lars Knudsen, Vincent Rijmen (March 1999). "On the Decorrelated Fast Cipher (DFC) and Its Theory" (PostScript). 6th International Workshop on Fast Software Encryption (FSE '99). Rome: Springer-Verlag. pp. 81–94. Retrieved 14 February 2007.
Louis Granboulan, Phong Q. Nguyen, Fabrice Noilhan, Serge Vaudenay (2000). "DFCv2" (PDF/PostScript). Selected Areas in Cryptography (SAC 2000). Waterloo, Ontario: Springer-Verlag. pp. 57–71. Retrieved 15 February 2007.

External links

SCAN's entry for DFC

v t e Block ciphers (security summary)

Common algorithms	AES Blowfish DES Triple DES Serpent Twofish

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

Other algorithms	3-Way Akelarre Anubis ARIA 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 Ladder-DES Libelle LOKI97 LOKI89/91 Lucifer M6 M8 MacGuffin Madryga MAGENTA MARS Mercy MESH MISTY1 MMB MULTI2 MultiSwap New Data Seal NewDES Nimbus NOEKEON NUSH PRESENT Q RC6 REDOC Red Pike S-1 SAFER SAVILLE SC2000 SHACAL SHARK Simon SMS4 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 No weak keys

Attack (cryptanalysis)	Brute-force (EFF DES cracker) MITM Linear (Piling-up lemma) Differential (Impossible Truncated Higher-order) Differential-linear Integral (aka Square) Boomerang Mod n Related-key Slide Rotational Timing XSL Interpolation Partitioning Davies' Rebound

Standardization	AES process CRYPTREC NESSIE

Utilization	Initialization vector Mode of operation Padding

v t e Cryptography

History of cryptography Cryptanalysis Cryptography portal Outline of cryptography

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

This article is issued from Wikipedia. The text is available under the Creative Commons Attribution/Share Alike; additional terms may apply for the media files.