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Unformatted text preview: tagged by use: A key dedicated for one purpose cannot accidentally be used for another. This concept of key control vectors is probably the most significant contribution of this system. Donald Davies and William Price discuss this key management protocol in detail . A Variation
A variation on this scheme of master and session keys can be found in . It’s built around network nodes with key notarization facilities that serve local terminals. It is designed to: — Secure two-way communication between any two terminal users. — Secure communications using encrypted mail. — Provide personal file protection. — Provide a digital signature capability. For communication and file transfer among users, the scheme uses keys generated in the key notarization facility and sent to the users encrypted under a master key. The identities of the users are incorporated with the key, to provide evidence that the session key has been used between a particular pair of users. This key notarization feature is central to the system. Although the system does not use public-key cryptography, it has a digital-signature-like capability: A key could have only come from a particular source and could only be read at a particular destination. 24.2 MITRENET
One of the earliest implementations of public-key cryptography was the experimental system MEMO (MITRE Encrypted Mail Office). MITRE is a DoD contractor, a government think tank, and an all-around bunch of smart guys. MEMO was a secure electronic mail system for users in the MITRENET network, using public-key cryptography for key exchange and DES for file encryption. In the MEMO system, all public keys are stored in a Public Key Distribution Center, which is a separate node on the network. They are stored in an EPROM to prevent anyone from changing them. Private keys are generated by users or by the system. For a user to send secure messages, the system first establishes a secure communications path with the Public Key Distributio...
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This note was uploaded on 10/18/2010 for the course MATH CS 301 taught by Professor Aliulger during the Fall '10 term at Koç University.
- Fall '10