System and method for protecting unauthorized access to data contents

• US 5,594,227 A
• Filed: 03/28/1995
• Issued: 01/14/1997
• Est. Priority Date: 03/28/1995
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Deo, Vinay
• Primary Examiner(s): Hajec, Donald T.
• Assistant Examiner(s): FILIPEK, JEFFER
• Application Number:
  US08/412,295
• Time in Patent Office: 658 Days
• Field of Search: 902/4, 902/5, 902/26, 235/380, 235/379
• US Class Current: 235/380
• CPC Class Codes: G06Q 20/341 Active cards, i.e. cards including their own processing means, e.g. including an IC or chip
• CPC Class Codes: G06Q 20/35765 Access rights to memory zones
• CPC Class Codes: G07F 7/1008 Active credit-cards provided with means to personalise their use, e.g. with PIN-introduction/comparison system
• CPC Class Codes: G07F 7/1025 Identification of user by a PIN code
• CPC Class Codes: G07F 7/1083 Counting of PIN attempts

Abstract

A smart card protection system is provided for protecting against unauthorized access of data contents on a smart card through human or electronic-machine tampering. The smart card protection system includes a smart card having an authorized password stored thereon for associated data and a smart card terminal to supply an entered password for accessing the data on the smart card. The smart card includes a comparator to compare the entered password to the stored password, and two counters: a fail counter and a delay counter. The fail counter keeps a fail count indicative of the number of times that the entered password fails to match the stored password. The fail counter is incremented when the entered password fails to match the stored password and decremented when the entered password successfully matches the stored password. The delay counter maintains a delay count that is incremented each time the comparator compares the entered password to the stored password regardless of a match. In the event that the fail count is not equal to its starting value of zero, the smart card denies access to the data contents. Access is denied even though a match might occur after initial misses because the fail count is not zero. Further, when access is denied, a delay period is imposed before comparing the next entered password received from the smart card terminal. The delay period increases each time based upon a function of the delay count.

Claims