Patent ID: 7412059
Filing Date: 2008-08-12
Classification: H04L

Abstract:
1. A method for allowing a sender having user equipment to send a secure message to a receiver having user equipment over a communications network to which the user equipment of the sender is coupled and the user equipment of the receiver is coupled, wherein a key management service is coupled to the communications network that has an associated key-management-service public key and key-management-service private key, wherein the sender encrypts the message using a message key to produce a message-key-encrypted message, the method comprising: at the sender, encrypting the message key and policy information using the key-management-service public key to generate a corresponding public-key-encrypted message key and public-key-encrypted policy information, wherein the policy information includes date-based constraints that restrict access to the message to a particular time; providing the message-key-encrypted message, the public-key-encrypted message key, and the public-key-encrypted policy information that includes date-based constraints that restrict access to the message to a particular time to the receiver; receiving the public-key-encrypted message key and public-key-encrypted policy information including the date-based constraints that restrict access to the message at the key management service from the receiver; decrypting the encrypted policy information including the date-based constraints at the key management service using the key management service's private key; determining, at the key management service, whether policy constraints imposed by the policy information including the date-based constraints that restrict access to the message have been satisfied; decrypting the public-key-encrypted message key at the key management service using the key management service's private key; and providing the resulting unencrypted version of the message key to the receiver if the policy constraints including the date-based constraints that restrict access to the message have been satisfied for the receiver to use in decrypting the message-key-encrypted message.