| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for sending a digital message from a sender to a recipient in a public-key based cryptosystem comprising an authorizer. <P>SOLUTION: An authorizer can be a single entity or comprise a hierarchical or distributed entity. The invention allows communication of message by an efficient protocol, not involving key status queries or key escrow, where a message recipient can decrypt a message from a message sender only if the recipient possesses up-to-date authority from the authorizer. The invention allows such communication in a system comprising a large number (for example, millions) of users. <P>COPYRIGHT: (C)2013,JPO&INPIT |
