Zodiac (cipher) explained

Zodiac
Designers:	Chang-Hyi Lee
Publish Date:	2000
Derived From:	SAFER, SHARK
Related To:	Xenon
Key Size:	128, 192, or 256 bits
Block Size:	128 bits
Structure:	Feistel network
Rounds:	16
Cryptanalysis:	Impossible differential cryptanalysis recovers 128-bit key in 2^119 encryptions

In cryptography, Zodiac is a block cipher designed in 2000 by Chang-Hyi Lee for the Korean firm SoftForum.

Zodiac uses a 16-round Feistel network structure with key whitening. The round function uses only XORs and S-box lookups. There are two 8×8-bit S-boxes: one based on the discrete exponentiation 45^x as in SAFER, the other using the multiplicative inverse in the finite field GF(2⁸), as introduced by SHARK.

Zodiac is theoretically vulnerable to impossible differential cryptanalysis, which can recover a 128-bit key in 2¹¹⁹ encryptions.

References

• • Deukjo Hong. Jaechul Sung. Shiho Moriai. Sangjin Lee. Jongin Lim. amp. Impossible Differential Cryptanalysis of Zodiac. 8th International Workshop on Fast Software Encryption (FSE 2001). 300 - 311. Springer-Verlag. April 2001. Yokohama. PDF. 10.1007/3-540-45473-X_25. 9783540438694. free. 2007-09-14. 2007-12-13. https://web.archive.org/web/20071213222753/http://www.mathmagic.cn/Crypt1998-2003/bibs/2355/23550300.htm. dead.

Further reading

• Cryptography and Information Security. Impossible Differential Cryptanalysis of Zodiac.. HONG D, SUNG J, MORIAI S, LEE S, LIM J. IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences. E85-A. 1. 38 - 43. 2002.
• Book: Square Attack on Reduced-Round Zodiac Cipher. Springer. Information Security Practice and Experience. 2008. 978-3-540-79103-4. 10.1007/978-3-540-79104-1_27. 377 - 391. Wen Ji. Lei Hu. Lecture Notes in Computer Science . 4991 . amp.