The ISC International Journal of Information Security

Abstract This paper reviews the characteristics of the main digest algorithms, and presents a new derivation of the leftover hash lemma, using the collision probability to derive an upper bound on the statistical distance between the key and seed joint probability, and the hash bit sequence distribution. The paper discussed the use of the hash function in cryptography and presented a new derivation of the upper bound on the statistical distance between the joint distribution of the key and the seed, and the distribution of the hash bit distribution, based on the collision probability. A cryptographic hash function is used to verify whether a data file maps onto a certain hash value. On the other hand, it is difficult to reconstruct the information based on the hash value. Therefore, it is used to assure data in- integrity, and is the building block of a Hash-based Message Authentication Code (HMAC), which provide message authentication.

Abstract This paper presents an investigation on the performance of the Non-Orthogonal Multiple Access (NOMA) in the power domain scheme. A Power Allocation (PA) method is proposed from NOMA throughput expression analysis. This method aims to provide fair opportunities for users to improve their performance. Thus, NOMA users can achieve rates higher than, or equal to, the rates obtained with the conventional Orthogonal Multiple Access (OMA) in the frequency domain schemes. The proposed method is evaluated and compared with others PA techniques by computer system level simulations. The results obtained indicate that the proposed method increases the average cell spectral efficiency and
maintains a good fairness level with regard to the resource allocation among the users within a cell.