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Cryptographic communication method and cryptographic communication device

  • US 5,136,642 A
  • Filed: 05/31/1991
  • Issued: 08/04/1992
  • Est. Priority Date: 06/01/1990
  • Status: Expired due to Term
First Claim
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1. A cryptographic communication method for carrying out cryptographic communication to transmit a message M from a sending station to a receiving station through a communication line by utilizing public information P2 of the receiving station, secret information S1 of the sending station, an identification number 101 of the sending station, and a secret key d2 of the receiving station, comprising the steps of;

  • obtaining the public information P2 in the sending station;

    generating a first random number r in the sending station;

    generating a second random number R according to a prescribed procedure by utilizing both the public information P2 and the first random number r in the sending station;

    generating a third random number X according to a prescribed procedure by utilizing the second random number R in the sending station;

    generating a cryptographic key K according to a prescribed procedure by utilizing the first random number r in the sending station;

    producing a ciphertext C from the message M by utilizing the cryptographic key K in the sending station;

    generating a first hashing result E by implementing a one-way hashing to hash both the ciphertext C and the third random number X in the sending station;

    generating key-distribution-information Y according to a prescribed procedure by utilizing the secret information S1, the second random number R, and the hashing result E in the sending station;

    sending the third random number X, the identification number ID1, the ciphertext C, and the key-distribution-information Y to the receiving station through the communication line;

    generating a second hashing result EO by implementing the one-way hashing to hash both the ciphertext C and the third random number X in the receiving station;

    restoring the cryptographic key K according to a prescribed procedure by utilizing both the secret key d2 and the third random number X in the receiving station; and

    obtaining the message M by decrypting the ciphertext C by utilizing the cryptographic key K in the receiving station.

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