Patent ID: 6940979

Claim:
A certificate for Public Key Infrastructure (PKI), the certificate validity being determined by the amount of ciphertext associated with the certificate, wherein when the amount of ciphertext generated is below a predetermined value, the certificate is valid, and when the amount of ciphertext generated reaches a predetermined value, the certificate is invalid, comprising: an extension including a Certificate Ciphertext Entitlement (CCE) value defining the amount of data that it is permissible for a certificate to encrypt before it must be rendered invalid; an object identifier defining the units for ciphertext entitlement; and an associated Ciphertext Generated Index (GCI) defining the count of how much cyphertext has been encrypted by the key, the certificate validity also being dependent on the elapsed time and revocation status wherein the certificate validity is defined by ( Certificate_Validity ) = k ( Ciphertext_Generated ) + ( Elapsed_Time ) ⋀ ( Revocation_Status ) wherein k is a constant value representing the assurance level of the keys in use.