Extensive studies have been made of the public key cryptosystems based on multivariate polynomials over F2. However most of the proposed public key cryptosystems based on multivariate polynomials, are proved not secure. In this paper, we propose several types of new constructions of public key cryptosystems based on randomly generated singular simultaneous equations. One of the features of the ...

Merkle and Hellman proposed a first knapsack cryptosystem. However, it was broken because the density is not sufficiently high. In this paper, we propose a a new trapdoor in modular knapsack PKC. Proposed scheme can use the message encoding. This method can use the method of enlarging messages over a finite field in order to realize a high density over 1. Keywords— Knapsack public-key cryptosys...

At present, electronic payment activities constructed on the Internet mainly employ the certificate-based public key cryptosystems to solve related security issues. But it is based on the condition that the certificate authority (CA) must be honest and needs to manage the key directory. Furthermore, it needs to spend extra time to verify the signature signed in the digital certificate by the CA...

In this paper, we propose two algorithms to improve the Merkle-Hellman knapsack public-key cryptosystem. First, we propose an approach to transform a superincreasing sequence to a " high den-sity'' knapsack sequence. The algorithm is easy to implement and eliminates the redundancy of many knapsack cryptosystems. Second, a linearly shift method is used to improve the security of the knapsack pub...

Throughout the history of cryptography, hundreds of cryptosystems have been developed. The earliest ones, as well as many later ones, relied on the complete secrecy in transferring keys between the sender and recipient. These kinds of systems, called secret key cryptosystem, have just a single key which is used for both encryption and decryption; therefore, these systems are more frequently kno...