FIELD: information technology.
SUBSTANCE: invention relates to methods and a system for providing an online service user with a dynamic code via a telephone. Method of providing an online service user with a dynamic code via a telephone includes stages of transmitting to the user by means of a network terminal connected to a computer server via a digital network an identifier for a computer server, which controls the online service, selecting by the codes server a calling line from a collection of available lines to call the user's telephone used for calling the user's telephone, determining a dynamic code designed for use in the online service, herewith the dynamic code is determined by the dynamic code allocation rule, which determines a subgroup of digits composing the number of the calling line, which is taken into account when making the dynamic code, and the number of the calling line is sent to the online service via the codes server, herewith the number of the calling line containing the dynamic code is determined by an algorithm used by the codes server depending upon a set of parameters included in the request for the dynamic code transmitted by the online service.
EFFECT: technical result is improvement of security level in relation to attacks of phishing type.
15 cl, 3 dwg
