The main problem in the use of cloud storage services is data protection: cloud service providers do not provide encryption functions. The existing solutions, that realize a principle of client-side encryption, do not provide secure maintenance in encryption keys management – a user is responsible for a task of safe transfer of encryption keys by himself. This thesis aims to develop and implement software that provides data security while using cloud storage services with the use of methods of secure generation and transfer of encryption keys. The main emphasis in the study is on the development and implementation of methods to derivate encryption keys on both image and password: using fractal curves and using DCT coefficients. The analysis with NIST statistical tests demonstrates good statistical properties of the output sequences while using medium size contrast images. The result of the thesis is desktop software that provides data security while using a cloud storage service. Implemented software interacts with the Yandex Disk cloud storage via REST API and ensures data security by performing encryption functions (derivation of encryption keys using developed methods, encryption and decryption). The proposed system carries basic functionality and ready to further expansion. Currently, the implemented software was handed over to a fabless-company for acceptance testing and to determine the directions of further improvements.