Kovalchuk AnatoliyLotoshynska NataliiaPodavalkina MariiaPelekh Khrystyna2022-11-032022-11-032020RSA algorithm elements in ternary affine transformations in encryption-decryption of images / Anatoliy Kovalchuk, Nataliia Lotoshynska, Mariia Podavalkina, Khrystyna Pelekh // Measuring Equipment and Metrology. – Lviv : Lviv Politechnic Publishing House, 2020. – Volume 81, № 4. – P. 25–29. – Bibliography: 15 titles.https://ena.lpnu.ua/handle/ntb/57006Regarding image encryption, a crucial task is to implement the application of such an RSA algorithm which will provide an opportunity: – not to decay the cryptographic stability of the RSA algorithm; – to ensure complete noisiness of an image to prevent the application of methods of visual image processing. An algorithm for encryption-decryption of monochrome images using elements of the RSA algorithm as the most resistant to unauthorized signal decryption in ternary affine transformations is proposed. The developed algorithm is applied to images in which there are strictly delineated contours. Elements of the RSA algorithm are proposed to be used to construct the coefficients of ternary affine transformations. The proposed algorithm has higher cryptographic stability compared to the RSA algorithm. The ways of applying the elements of the RSA algorithm in affine transformations in encryption-decryption of images are described in this article. The results of modeling the affine modified cipher for cryptographic transformations of black and white monochrome images of a given dimension are presented. Modified models and algorithmic procedures of key generation processes, direct and inverse cryptographic transformations, which are reduced to matrix element-by-element operations by module, are developed. Key words: Encryption; Monochrome image; Ternary affine transformation; Contour; Decryption.enArticle