Malaysian Journal of Mathematical Sciences 7(S): 1-17 (2013) Special Issue: The 3rd International Conference on Cryptology & Computer Security 2012 (CRYPTOLOGY2012) MALAYSIAN JOURNAL OF MATHEMATICAL SCIENCES Journal homepage: http://einspem.upm.edu.my/journal On the Hastad's Attack to LUC 4,6 Cryptosystem and Compared with Other RSA-Type Cryptosystem 1,2*Wong Tze Jin, 3Hailiza Kamarulhaili and 2,4 Mohd. Rushdan Md Said 1Department of Basic Science and Engineering, Faculty of Agriculture and Food Sciences, Universiti Putra Malaysia Bintulu Campus, 97008 Bintulu, Sarawak, Malaysia 2Institute for Mathematical Research, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia 3School of Mathematical Sciences, Universiti Sains Malaysia, 11800 Pulau Pinang, Penang, Malaysia 4Department of Mathematics, Faculty of Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia E-mail:
[email protected] *Corresponding author ABSTRACT The LUC 4,6 cryptosystem is a system analogy to RSA cryptosystem and extended from LUC and LUC 3 cryptosystems. Therefore, the security problem of the LUC 4,6 cryptosystem is based on integer factorization which is similar to RSA, LUC and LUC 3 cryptosystems. The Hastad's attack is one of the polynomial attack which relied on the polynomial structure of RSA-type cryptosystem. In this paper, Hastad's Theorem will be used to solve a system of multivariate modular equations and Coppersmith Theorem will be used to find a root of a modular equation. Thus, the number of plaintexts which are required to succeed the attack can be found. Keywords: Hastad's Theorem, Coppersmith Theorem, Lucas Sequence, Dickson Polynomial. Wong Tze Jin, Hailiza Kamarulhaili & Mohd.