A user's validation method, comprising: - receiving, by a computer, every certain period time, first data about a user, wherein the first data being passively collected by one or more sensors of at least one portable computer device of the user or from user usage events of the at least one portable computer device; - receiving, by the computer, second data about the user, wherein the second data being actively collected via a computer device of the user; - computing, by the computer, a digital behavioral fingerprint of the user by processing the received first data; and - executing, by the computer, a first authentication step of an identity of the user by computing a user's authenticity score using the computed digital behavioral fingerprint, wherein if the user's authenticity score is equal or below a first threshold the identity of the user is established as valid, otherwise the computer establishes that a second authentication step has to be executed; characterized in that the method further comprises: - checking, by the computer, the validity of the received second data by computing a user's conformity score, the latter being computed as the difference between an expected second data and the received second data, the expected second data being based on both second data of other users and previous second data of the user, wherein if the user's conformity score is equal or below to a second threshold the received second data is established as valid, otherwise the computer establishes that the received second data is incorrect; and - providing, by the computer, a personalized service or recommendation to the user by correlating the received first data with the received second data only if the identity of the user and the second data have been established as valid. - receiving, by a computer, every certain period time, first data about a user, wherein the first data being passively collected by one or more sensors of at least one portable computer device of the user or from user usage events of the at least one portable computer device; - receiving, by the computer, second data about the user, wherein the second data being actively collected via a computer device of the user; - computing, by the computer, a digital behavioral fingerprint of the user by processing the received first data; and - executing, by the computer, a first authentication step of an identity of the user by computing a user's authenticity score using the computed digital behavioral fingerprint, wherein if the user's authenticity score is equal or below a first threshold the identity of the user is established as valid, otherwise the computer establishes that a second authentication step has to be executed; - checking, by the computer, the validity of the received second data by computing a user's conformity score, the latter being computed as the difference between an expected second data and the received second data, the expected second data being based on both second data of other users and previous second data of the user, wherein if the user's conformity score is equal or below to a second threshold the received second data is established as valid, otherwise the computer establishes that the received second data is incorrect; and - providing, by the computer, a personalized service or recommendation to the user by correlating the received first data with the received second data only if the identity of the user and the second data have been established as valid.