METHOD AND APPARATUS FOR USER AUTHENTICATION
 Inventor: Robert Peter Khello, Norsborg. Sweden
 Assignee: Telefonaktiebolaget LM Ericsson. Stockholm, Sweden
 Appl. No.: 529,405
 Filed: Sep. 18, 1995
 Int CI.6 H04K 1/00
 U.S. CI 380/23; 380/46
 Field of Search 380/23, 25, 49,
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Primary Examiner—David C. Cain
Attorney, Agent, or Firm—Nixon & Vanderhye P.C.
A user authentication service is disclosed which is both highly secure and user friendly. To access a particular service, a user simply enters a personal identification type number (PIN) using a portable terminal device which encodes the PIN. More specifically, a character position of the user's PIN is determined, and a random code having a length selectable at each service transaction by the user is generated. The user's PEST is encrypted using one of plural available, pseudo-randomly encrypting algorithms to provide an encrypted PIN. The encrypted PIN is then combined with the code at the determined position before being transmitted over a communications network. When received, the encoded PIN is decoded using an analogous procedure to determine if the user is authorized. A plurality of security levels are provided with each level having a plurality of encryption algorithms and with each increasing level providing encryption algorithms of increasing complexity and sophistication. A user may also change a current PIN from the portable device easily and securely without having to contact a service center.
54 Claims, 12 Drawing Sheets