Secure messaging systems
First Claim
1. A secure messaging system comprising:
- at least three terminals;
a key distribution center;
communication means for carrying messages amongst the terminals and between the terminals and the center; and
means for providing a key means, a key transport key, and a plurality of data transport keys,the center being responsive to a message requesting a communication link between first and second ones of the terminals to encrypt the key means according to the key transport key and to send the encrypted key means to both terminals,each terminal being operative to decrypt the key means, to encrypt an associated one of the data transport keys according to the key means, to send the encrypted data transport key to the other terminal, to encrypt data according to the data transport keys, and to exchange the encrypted data with the other terminal.
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Accused Products
Abstract
A secure communication system wherein encrypted messages are passed between selected pairs of user terminals in a secure messaging system. A link is first established between the two terminals of the pair, one terminal sending a request to a key distribution center (KDC), which then provides encrypting keys to both terminals so they can communicate with each other. (Messages involving the KDC are themselves protected by encryption). The keys sent out by the KDC are key transporting keys, which are used by the terminals solely to transport data transporting keys between each other. The data transporting keys are used to transport (encrypt) the actual messages, and for security are changed after a usage count is reached; a fresh data transporting key is then generated and transferred under the key transporting key. This minimizes the load on the KDC. A hierarchy or key transporting keys can be used. The KDC (but not the user terminals) maintains a log to enable recover after a system failure. A journey key can be generated to allow a user temporary access to a link from a third terminal.
199 Citations
10 Claims
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1. A secure messaging system comprising:
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at least three terminals; a key distribution center; communication means for carrying messages amongst the terminals and between the terminals and the center; and means for providing a key means, a key transport key, and a plurality of data transport keys, the center being responsive to a message requesting a communication link between first and second ones of the terminals to encrypt the key means according to the key transport key and to send the encrypted key means to both terminals, each terminal being operative to decrypt the key means, to encrypt an associated one of the data transport keys according to the key means, to send the encrypted data transport key to the other terminal, to encrypt data according to the data transport keys, and to exchange the encrypted data with the other terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification