1 ) A method comprising: sensing, by the processor, a target of at least one user interacting with a touchscreen of a mobile device; receiving, by a processor via the touchscreen, interaction data of the target to authorize the user for executing a function with the mobile device; extracting, by the processor, key frames from the received interaction data; determining, by the processor, feature data of the target from the extracted key frames; determining, by the processor, the target from the feature data; comparing, by the processor, the feature data of the target with pre-stored user information; identifying upon the comparison, by the processor, the user based on a match between the feature data and at least a portion of the pre-stored user information; authorizing, by the processor, the user for the function if the user is identified based on the match; and blocking, by the processor, the user from executing the function if there is no match between the feature data and at least a portion of the pre-stored user information.