| 摘要 |
Key server (216, 320, 420) based systems (210, 310, 410) permitting sender and recipient participants (212, 312, 412) to securely exchange communications (218, 324, 424). The key server (216, 320, 420) creates, stores, and releases keys that the participants use to protect the message. The participants employ keys (220, 330, 430), typically provided by the key server, to exchange the communications in encrypted form. Assertions (322, 422) from an authentication authority (318, 418) can be used to establish identities of the participants. Positive and negative events (342, 344) can be determined based on controlling events (340) and if, when, how often requests for a key for decryption occur. The key server can also store information from assertions in association with a transaction ID, to establish senders and recipients of communications in a manner that cannot plausibly be repudiated and can easily be audited. |
