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Migration from in-clear to encrypted working over a communications link

  • US 6,832,313 B1
  • Filed: 06/01/2000
  • Issued: 12/14/2004
  • Est. Priority Date: 07/21/1999
  • Status: Active Grant
First Claim
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1. A computer system comprising a first nodes, a second node and a communication link connecting the first node and the second node, wherein:

  • (a) the system is initially capable of operating in a plurality of modes, including a first mode corresponding to in-clear working over the link, a second mode corresponding to encrypted working over the link, and a third mode, employed for migration from in-clear working over the link to encrypted working over the link, in which said first node is set to “

    initiate encryption” and

    said second node is set to “

    accept encryption”

    ;

    (b) the third mode provides in-clear working until means required for encrypted working are installed at both the first and the second nodes, when encrypted working is provided over the link and from which point in time only encrypted working is possible over the link;

    (c) the means required for encrypted working comprise a long term key, which long term key is used to establish a message encryption key to be employed by the first and the second nodes for encryption and decryption of messages transmitted over the link;

    (d) the first and second nodes include respective caches in which said message encryption key is stored upon its establishment; and

    (e) when there is a failure to establish a said message encryption key a special key value is cached in the cache of said first node, the presence of which special key value serves to suspend attempts to establish a said message encryption key.

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