Abstract
Merkle and Hellman proposed a knapsack scheme using the superincreasing sequence as a trapdoor. Kasahara and Murakami introduced the trapdoor using even-odd check in shifted values of the secret sequence. These sequences are typical trapdoors of knapsack schemes using the modular multiplication. In this paper, we propose a method of combining these trapdoors. We also propose a high-density knapsack cryptosystem using the proposed trapdoor. Moreover, we discuss on the security of the proposed scheme against Shamir's attack and the low-density attack which are conventional attacks for knapsack schemes.
