Further notes for a self-study course in block-cipher cryptanalysis

Cryptologia, Apr 2002 by Phan, Raphael Chung-Wei

3.25 Improved Square Attack of Hierocrypt

Read Toshiba Corporation, "Specification of Hierocrypt-3", NESSIE submission; and Toshiba Corporation, "Specification of Hierocrypt-Ll", NESSIE submission; both available at http://www. cosic. esat.kuleuven. ac. be/nessie. Try to see if you can apply the Square attack on these versions of Hierocrypt. The solutions are in Toshiba Corporation, "Security Evaluation: Hierocrypt-3", 2000; and Toshiba Corporation, "Security Evaluation: Hierocrypt-Ll", both available at http: //www.cosic.esat.kuleuven.ac.be/nessie. Also see if you can improve on the attacks. Read P. S. L. M. Barreto, V. Rijmen, J. Nakahara Jr., B. Preneel, J. Vandewalle, and H. Y. Kim, "Improved Square Attacks Against Reduced-round Hierocrypt", Advances in Cryptology Proceedings of FSE 2001, to appear. Try to apply the new cryptanalytic methods on Hierocrypt.

CONCLUSION

How do I study cryptanalysis? When will I be able to really attack a cipher? Ask any experienced cryptanalysts these questions and they will answer that the key to learning cryptanalysis is practice, practice, practice. Once you get a feel of the concepts of the various cryptanalytic methods, try your hand at simplified or reduced versions of ciphers and you will discover the world of cryptanalysis open before your eyes.

REFERENCES

1. European Commission. 2000. New European Schemes for Signatures, Integrity, and Encryption (NESSIE). Available at http://www.cosic.esat. kuleuven.ac.be/nessie.

2. NIST. 1999. AES Round 2 Finalists. August. Available at http: //csrc. nist.gov/encryption/aes/round2/round2.htm.

3. NIST. 2000. AES Development Effort. Available at http: //csrc. nist. gov/encryption/aes/index2.html.

4. NIST. 2000. Commerce Department Announces Winner of Global Information Security Competition. October. Available at http://www.nist. gov/ public-affairs/releases/gOO-176. htm.

5. Schneier, Bruce. 2000. A Self-Study Course in Block-cipher Cryptanalysis. Cryptologia. 24(1): 18-33.

Raphael Chung-Wei Phan

ADDRESS: Swinburne Sarawak Institute of Technology, Ist Floor, State Complex, 93576 Kuching, Sarawak, Malaysia. rphan@swinburne.edu.my.

BIOGRAPHICAL SKETCH

Raphael Phan Chung Wei received the BEng (Hons) degree in Computer Engineering from the Multimedia University (MMU), Cyberjaya, Malaysia in 1999. He was a tutor with the Faculty of Engineering, MMU and researcher at the Center for Smart Systems and Innovation, MMU from June 1999 to June 2001 where he pursued his MEngSc degree by research in the Cryptanalysis of the Advanced Encryption Standard & Skipjack. He is currently an Engineering lecturer with the Swinburne Sarawak Institute of Technology, Kuching, Malaysia. His research interests include cryptography, cryptanalysis, block ciphers, antivirus technology and programming.