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...

The submodular knapsack set is the discrete lower level set of a submodular function. The modular case reduces to the classical linear 0-1 knapsack set. One motivation for studying the submodular knapsack polytope is to address 0-1 programming problems with uncertain coefficients. Under various assumptions, a probabilistic constraint on 0-1 variables can be modeled as a submodular knapsack set....

The (offline) maximization (resp., minimization) knapsack problem is given a set of items with weights and sizes, and the capacity of a knapsack, to maximize (resp., minimize) the total weight of selected items under the constraint that the total size of the selected items is at most (resp., at least) the capacity of the knapsack. In this paper, we study online maximization and minimization kna...

This paper introduces a knapsack cryptosystem based on the problem of discrete logarithm. The proposed algorithm obtains the public knapsack values by finding the discrete logarithms of the secret knapsack ones. Also, it encrypts the message block by obtaining its binary bits and then computing the modular multiplication of the public knapsack values corresponding to the 1-bits of the binary fo...

We introduce methods to count and enumerate all maximal independent, all maximum independent sets, and all independent sets in threshold graphs and k-threshold graphs. Within threshold graphs and k-threshold graphs independent sets correspond to feasible solutions in related knapsack instances. We give several characterizations for knapsack instances and multidimensional knapsack instances whic...

the facet of knapsack ploytope, i.e. convex hull of 0-1 points satisfying a given linear inequality has been presented in this current paper. such type of facets plays an important role in set covering set partitioning, matroidal-intersection vertex- packing, generalized assignment and other combinatorial problems. strong covers for facets of knapsack ploytope has been developed in the first pa...

In the incremental knapsack problem (IK), we are given a knapsack whose capacity grows weakly as a function of time. There is a time horizon of T periods and the capacity of the knapsack is Bt in period t for t = 1, . . . , T . We are also given a set S of N items to be placed in the knapsack. Item i has a value of vi and a weight of wi that is independent of the time period. At any time period...

With growth of networked systems and applications such as ecommerce, the demand for internet security is increasing. Information can be secured using cryptography, anti-virus, malwares, spywares, firewall etc. In cryptology, cryptanalysis is a discipline where the ciphers are attacked and broke thus enabling the developers to strengthen the cipher. Nowadays cryptanalysis of ciphers is gaining p...

We observed few important facts that concerns with the new proposal of knapsack cipher 0/255, recently published by Pham [1]. The author claimed that the time complexity for solving new improved trapdoor knapsack is O(256). In this paper, we show that the knapsack cipher 0/255 can be solved in the same time that is required for solving the basic knapsack-cipher proposed by Merkle and Hellman [2...