Abstract: A method for controlling and tracking access to disseminated information involves encrypting data using a key that is maintained in a key repository. A user requests a message ID and key from the key repository. The key repository issues a message ID and key to the user. The user generates an encrypted message using the key. The encrypted message is then distributed with the message ID to one or more recipients. To read the encrypted message, a particular recipient obtains the key for the message from the key repository by providing the message ID to the key repository. The particular recipient then decrypts the message using the key provided by the key repository. Messages are deleted, in the sense of becoming unusable, by deleting the corresponding key from the key repository. A log is provided to track key repository activity including the issuance of keys and key requests from message recipients.

Abstract: In general, data exchanged between users is protected using any of various encoding approaches. An example of encoding is encryption, but any kind of encoding may be used. The data used to encrypt the data exchanged between the users, referred to as a “key”, is maintained only in a key repository. Users must obtain a key from the key repository to either encode or decode, encrypt or decrypt data, after which the user's copy of the key is destroyed or otherwise rendered inoperable. A key management policy is employed to control access to the keys maintained by the key repository. Encoding algorithms may be dynamically changed over time. Users may negotiate different algorithms to be used with specific users or messages. Thus, different algorithms may be used between different sets of users depending upon what the member users of those sets negotiate among themselves. The frequency at which algorithms are changed may also be separately negotiated between users.