METHOD OF LIMITING KEY USAGE IN A POSTAGE METERING SYSTEM THAT PRODUCES CRYPTOGRAPHICALLY SECURED INDICIUM

摘要

A method for requiring that a key used in a cryptographic apparatus be changed includes the steps of: storing a constraint value for a non-time parameter of the cryptographic apparatus, the non-time parameter being related to the operation of the cryptographic apparatus; and requiring the key to be changed when an actual value of the non-time parameter is not within a range defined by the constraint value.