×

Extended key preparing apparatus, extended key preparing method, recording medium and computer program

  • US 20020006196A1
  • Filed: 03/20/2001
  • Published: 01/17/2002
  • Est. Priority Date: 07/13/2000
  • Status: Active Grant
First Claim
Patent Images

1. An extended key preparing apparatus wherein extended keys are prepared in common key cryptosystem from a cryptographic key input, comprising:

  • a dividing unit which divides binary digit string of said cryptographic key into a plurality of elements each composed of a predetermined bit length;

    an intermediate data preparing unit which prepares a plurality of intermediate data by applying a plurality of times an operation wherein a predetermined constant is used to the respective elements divided by said dividing unit;

    a selecting unit which selects a plurality of intermediate data corresponding to the number of stages of extended keys from the plurality of the intermediate data prepared by said intermediate data preparing unit; and

    an extended key preparing unit which prepares the extended keys corresponding to said number of stages by converting irreversibly the plurality of the intermediate data selected by said selecting unit.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×