Patent ID: 7415615

Claim:
A method for authenticating a user in a digital communication system, said system comprising at least one input device providing a user interface to the system, an authentication manager for authenticating the user to the system and a communication network connecting said input device and said authentication manager, said method comprising: receiving identification information about the user at said authentication manager from said input device; receiving a one time code (OTC) at said authentication manager from said input device; identifying, based on said identification information, a sequence of verification OTCs associated with said user, said sequence of verification OTCs forming a big access window; choosing at least one of the verification OTCs of said sequence, said chose verification OTCs forming a small access window; and comparing the at least one chosen verification OTC of the small access window and the OTC received from the input device, and in case of a match authenticating the user to the system; and in case of a non-match: requiring a second OTC from the user; searching at least a part of the remaining sequence of verification OTCs of the big access window for two verification OTCs in sequence matching the two OTCs received from the user; and in case of a match authenticating the user to the system.