Математичне та комп'ютерне моделювання 94 an estimation of the proposed method efficiency is obtained. Its comparison with the previously known method is made. It is shown that the proposed method has greater efficiency in terms of the complexity and volume of necessary memory, although it requires more noised codewords that are necessary for code generating matrix recovering. Depending on recovered codes parameters and the probabilities of distortion in the communication channel, benefits in

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... rms of the complexity of the proposed method in comparison with the previously known is from 36 2 up 67 2 once. The practical applicability of the proposed method for cases, where the previously known method is practically not realizable, is confirmed. Key words: information security, deducing of information, discrete mappings recovering, linear block code, system of liner equations with noised right-hand sides, BKW algorithm.