Patent ID: 6948064

Claim:
In a cryptographic system having one of a plurality of security-relevant states, an interactive method of controlling the transition of said system from an existing state to a future state under control of one or more authorities, said method being performed by said cryptographic system and comprising the steps of: storing control information specifying permissible future states based on a current state and a requesting authority; receiving a query from an authority as to the current state of the cryptographic system; providing a reply to said authority in response to said query, said reply containing nonsecret state information regarding the current state of said cryptographic system and reply authentication information for enabling said authority to determine whether said reply originated from said cryptographic system; receiving a request from an authority to change the current state of the cryptographic system, said request containing state change information indicating a proposed future state of said cryptographic system and request authentication information for enabling and cryptographic system to determine whether said request originated from said authority; determining using said request authentication information whether said request originated from said authority; and performing said request only if the request is determined to have originated from said authority and the proposed future state is a permissible future state as specified by said control information.