Abstract: The invention relates to means for protecting information systems against non-authorized intrusion. The invention makes it possible to form a unified loop for protecting the distributed data processing. To access a computer system from a user device and from a server for the distributed data processing, a system of internal and external keys based on secret keys received from a center for certification, generation and distribution of keys is formed. Secret internal single-use keys for a symmetrical encryption mode used for data transmission, storage and processing are generated, and a connection request to a pre-selected server is sent from the user device to the certification center. Public keys, by which the external single-use keys for symmetrical encryption mode are generated, are received. For transmission to the server, the information transmitted is encrypted using stochastic coding involving the use of external single-use keys.