Patent ID: 8924719

Claim:
A document management system comprising: a sender; plural target recipients; and a server coupled between the sender and the target recipients to receive from the sender and to provide to at least some of the target recipients a message, wherein the provided message is encrypted at least for storage at the server using a sender key and is decryptable using a corresponding message decryption key that is, in turn, separately encrypted for each of the target recipients using respective encryption keys associated with the target recipients themselves, thereby resulting in a plurality of recipient-associated encrypted decryption keys; the server providing each of the target recipients with at least a respective one of the recipient-associated encrypted decryption keys for decryption by the respective target recipient to recover the underlying message decryption key and to thereby provide the respective target recipient with access to the encrypted message, and wherein the sender system sends the recipient-associated encrypted decryption keys to the server for inclusion in a list of authorized encrypted decryption keys, and wherein, responsive to the sender, at least one but less than all of the recipient- associated encrypted decryption keys on the list is changed, but not the encrypted message itself which remains unchanged.