Encoded animated images and methods of generating, displaying, and reading encoded animated images, in particular for authorizing operations on online services

A method for generating, displaying and reading an encoded animated image by an online service, the encoded animated image comprising a plurality of frames configured to be displayed sequentially on a graphical interface, an encoded payload comprising a One-Time Password code, a transaction identification code and a string with the details of the transaction itself, the encoded payload being distributed over at least two frames of the plurality of frames according to a reversible encoding function,

• the method comprising the following steps:
• providing a random function for generating OTP codes, a reversible coding function, and a recognition function resident and executable on a web server associated with the online service;
• providing a reading and decoding function and an identification function resident and executable on a client device associated with an authenticated user, the client device being equipped with a camera and communicating with the web server;
• generating an OTP code through the random function, the OTP code being at least associated with an authenticated browsing session of the client device on the web server, the transaction identification code and the details of the transaction itself to form a payload;
• generating the encoded animated image comprising a plurality of frames configured to be displayed in sequence on a graphical interface, encoding the payload by dividing it into at least two parts and distributing these on at least two frames of the plurality of frames by means of the reversible encoding function;
• reproducing the plurality of frames in sequence on a graphical interface in communication with the web server, so as to display the encoded animated image;
• reading and decoding the encoded payload using the reading and decoding function when the camera of the client device frames the encoded animated image displayed on the graphical interface;
• generating an identification code by processing the decoded payload using the identification function and sending it to the web server;
• classifying the client device as legitimate when the identification code processed through the recognition function corresponds to that expected for the corresponding OTP code.