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Hybrid public key algorithm/data encryption algorithm key distribution method based on control vectors

  • US 5,142,578 A
  • Filed: 08/22/1991
  • Issued: 08/25/1992
  • Est. Priority Date: 08/22/1991
  • Status: Expired due to Term
First Claim
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1. In a data processing system having a plurality of communicating nodes, at least a pair of nodes in the system exchanging cryptographic communications, an apparatus for enabling a first node of the pair to control a crypto variable after its transmission from the first node to a second node of the pair, comprising:

  • a first storage means at a transmitting node in the system for storing a crypto variable which is to be transmitted to a receiving node in the system;

    a second storage means at said transmitting node for storing control information to control said crypto variable after it is transmitted from said transmitting node said control information including a control vector to limit the uses of said crypto variable;

    a third storage means at said transmitting node for storing a first key expression;

    concatenating means at said transmitting node, coupled to said first and second storage means, for concatenating said crypto variable with said control information, forming a key block;

    encryption means at said transmitting node, coupled to said third storage means and said concatenating means, for encrypting said key block with said first key expression, forming an encrypted key block;

    transmitting means at said transmitting node coupled to said encryption means and coupled over a communications link to a receiving means at said receiving node, for transmitting said encrypted key block to said receiving node;

    said transmitting means coupled to said second storage means, for transmitting a second copy of said control information to said receiving node;

    fourth storage means at said receiving node, for storing a second key expression corresponding to said first key expression;

    decryption means at said receiving node coupled to said receiving means and to said fourth storage means, for decrypting said encrypted key block using said second key expression, to obtain a recovered key block;

    extraction means at said receiving node coupled to said decryption means, to extract said control information and said crypto variable from said recovered key block;

    comparison means at said receiving node coupled to said extraction means and coupled to said receiving means for comparing said control information extracted from said recovered key block to said second copy of said control information, said comparison means having an enabling output for signaling when said comparison is satisfied;

    control means coupled to said extraction means and having an enabling input coupled to said output of said comparison means, for controlling said crypto variable with said control information.

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