Device, system, and method of password-less user authentication and password-less detection of user identity

A method comprising:

• differentiating between a first human user and a second human user of a computerized service via a password-less user-authentication process, by performing:
• (a) selecting, from a pool of task attributes, a particular set of task attributes;
• wherein the set of task attributes comprises at least:
• (i) a particular shape for on-screen tracing, and (ii) at least one other task attribute;
• and automatically generating on-the-fly a particular unique and non-user-defined task, that is intended to be repeatedly performed by a specific user via an input unit of an electronic device;
• (b) generating the unique and non-user-defined task, in which said specific user is requested to perform gestures that correspond to said task, wherein said generating comprises presenting to said specific user instructions on how to complete said task without requiring said user to remember or memorize any data-item or password or Personal Identification Number (PIN);
• and collecting user interactions data via the input unit while the user is performing the task;
• (c) repeating step (b) for at least N iterations for said specific user, wherein said same unique and non-user-defined task is repeated in each one of said iterations, wherein N is a positive integer;
• and wherein said same unique and non-user-defined task is consistently repeated across multiple log-in sessions of said specific user;
• (d) during step (b) and during step (c), determining from said user interactions data a user-specific cognitive behavioral biometric profile that characterizes a cognitive behavioral manner in which said user repeatedly performs said same unique and non-user-defined task across said N iterations;
• (e) storing the user-specific cognitive behavioral profile in a repository, indicating that said user-specific cognitive behavioral profile is associated with at least one of:
• (i) said specific user, (ii) said electronic device;
• (f) subsequently, generating said same unique and non-user-defined task again upon a subsequent request of a user to access said computerized service, and collecting fresh user interactions data from fresh performance of said task;
• (g) if the fresh user interactions data that was collected from said fresh performance of said same unique and non-user-defined task, does not match the previously-stored user-specific cognitive behavioral biometric profile, then un-authorizing access of the user to the computerized service.