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Protected communication method and system

  • US 5,703,948 A
  • Filed: 10/11/1994
  • Issued: 12/30/1997
  • Est. Priority Date: 02/14/1994
  • Status: Expired due to Term
First Claim
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1. A method of transmitting encrypted messages between two units, including initializing the two units with respect to each other, and thereafter transmitting the messages between the two units encrypted by means of dynamic random keys which are changed internally within the two units in synchronism with each other;

  • wherein one unit, serving as the transmitter party for a message, divides the message into a plurality of segments, encrypts each segment by an encrypting key which changes randomly from segment to segment, and transmits the encrypted segments;

    wherein the other unit, serving as the receiver party for the respective message, receives the encrypted segments, divides each received message into the same segments as the transmitter, and decrypts each segment by the use of a decrypting key which initially matches the encrypting key and which changes randomly from segment to segment in the same manner as the encrypting key;

    wherein the encrypting key is the output of a state machine at the transmitter, which state machine changes its state in a random manner from segment to segment according to at least one random manner from segment to segment according to at least one random characteristic transmitted with the respective segment;

    and wherein the decrpting key is the output of a state machine at the receiver, which latter state machine also changes its state in a random manner from segment to segment according to the same random characteristic of the respective segment.

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