An authenticating system comprising: a user interface for (i) presenting, for a login candidate, a set of one or more authentication screens of a variable challenge level, at least one of the set of authentication screens being configured to prompt the candidate to produce a graphic pattern of a given user of a plurality of registered users, wherein the login candidate is identifying as the given user, and (ii) observing characteristics of the candidate; a server storing respective model characteristics for each of the plurality of registered users; and hardware and/or software logic configured to execute a process comprising based at least in part on a comparison of the observed characteristics of the login candidate with the model characteristics stored for the given user, forming an assessment of risk that the login candidate is unauthentic, and adjusting the challenge level according to the assessment of risk, through directing the login candidate to one of a set of at least two authentication subprocesses, wherein in a first subprocess of the at least two authentication subprocesses corresponding to a higher value of the assessment of risk that the login candidate is unauthentic, the candidate is required to produce the graphic pattern of the given user from a set of basic elements, and in a second subprocess of the at least two authentication subprocesses corresponding to a lower value of the assessment of risk, the candidate is required to produce the graphic pattern by selecting, from an array of alternative graphic patterns, an acceptable pattern from one or more acceptable patterns, wherein each pattern of the one or more acceptable patterns of the array of alternative graphic patterns is a variant of the graphic pattern that has been registered for the given user, such that, when a given one of the acceptable patterns is selected by the candidate, the selected graphic pattern is considered a correct selection. a user interface for (i) presenting, for a login candidate, a set of one or more authentication screens of a variable challenge level, at least one of the set of authentication screens being configured to prompt the candidate to produce a graphic pattern of a given user of a plurality of registered users, wherein the login candidate is identifying as the given user, and (ii) observing characteristics of the candidate; (i) presenting, for a login candidate, a set of one or more authentication screens of a variable challenge level, at least one of the set of authentication screens being configured to prompt the candidate to produce a graphic pattern of a given user of a plurality of registered users, wherein the login candidate is identifying as the given user, and (ii) observing characteristics of the candidate; a server storing respective model characteristics for each of the plurality of registered users; and hardware and/or software logic configured to execute a process comprising based at least in part on a comparison of the observed characteristics of the login candidate with the model characteristics stored for the given user, forming an assessment of risk that the login candidate is unauthentic, and adjusting the challenge level according to the assessment of risk, through directing the login candidate to one of a set of at least two authentication subprocesses, wherein in a first subprocess of the at least two authentication subprocesses corresponding to a higher value of the assessment of risk that the login candidate is unauthentic, the candidate is required to produce the graphic pattern of the given user from a set of basic elements, and in a second subprocess of the at least two authentication subprocesses corresponding to a lower value of the assessment of risk, the candidate is required to produce the graphic pattern by selecting, from an array of alternative graphic patterns, an acceptable pattern from one or more acceptable patterns, wherein each pattern of the one or more acceptable patterns of the array of alternative graphic patterns is a variant of the graphic pattern that has been registered for the given user, such that, when a given one of the acceptable patterns is selected by the candidate, the selected graphic pattern is considered a correct selection.