USAGE OF HASH METHODS IN THE CRYPTOGRAPHIC DATA ANALYSIS

Abstract

The tasks of information security system include identifying potential or actual sources of threat to system’s work and minimizing consequences of unauthorized influence on it. While solving them, arises the need of restoration of the initial state of the information system, especially the data integrity. While performing information message analysis the other task may be finding differences between two data fragments or their instances. This paper offers methods of the complex solution of the information security tasks and the analysis of data streams using the means of cryptography and presents the experience of developing the reliable implementation of these methods. The developed methods allow detecting falsifications in data part of the sent message and restoring the initial message. During the cryptographic analysis, the area of change in a data block is localized using cross hashing which is performed by computing the hash of information message block by block. The result is the program implementation of the offered method of information stream analysis that is based on comparing three frames of input data. The effectiveness of detecting falsifications in a data stream depending on algorithm’s sensitivity was researched with the developed instrument. The dependence of the share of falsifications detected by the system in the information block on the established maximum allowable relative deviation from the median and the properties of the input stream, in particular, the division of the input data into frames, was experimentally revealed. It is expected that the advantages of the method will be higher in the preliminary stage of data flow analysis related to its segmentation before addressing the selected fragments to more accurate and specialized algorithms.