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Enciphering/deciphering device and method, and encryption/decryption communication system

  • US 5,870,477 A
  • Filed: 03/29/1996
  • Issued: 02/09/1999
  • Est. Priority Date: 09/29/1993
  • Status: Expired due to Fees
First Claim
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1. An encryption/decryption communication system in which a first enciphering/deciphering device and a second enciphering/deciphering device are connected to each other through communicating means, whereinsaid first enciphering/deciphering device comprisesdata encryption key forming means for forming a data encryption key used for enciphering plaintext data,data enciphering means for enciphering said plaintext data using said data encryption key to form ciphertext data,key enciphering means for enciphering said data encryption key using a management key to form an enciphered key,first authenticator enciphering means for enciphering an authenticator for confirming whether or not transmitted data is correctly transmitted and received using said data encryption key to generate a first enciphered authenticator, andtransmitting means for transmitting said ciphertext data, said enciphered key and said first enciphered authenticator,said second enciphering/deciphering device comprisesreceiving means for receiving the ciphertext data, the enciphered key, and the first enciphered authenticator transmitted by said transmitting means,key deciphering means for deciphering the enciphered key received by said receiving means using the same management key as the management key used in said first enciphering/deciphering device to form a data encryption key,data deciphering means for deciphering the ciphertext data received by said receiving means using the data encryption key formed by said key deciphering means to form plaintext data,authenticator deciphering means for deciphering the first enciphered authenticator received by said receiving means using the data encryption key formed by said key deciphering means,second authenticator enciphering means for enciphering the authenticator obtained as a result of the deciphering by said authenticator deciphering means using said management key to form a second enciphered authenticator, andreturning means for returning said second enciphered authenticator to said first enciphering/deciphering device, andsaid first enciphering/deciphering device deciphers the second enciphered authenticator transmitted from said second enciphering/deciphering device using said management key, and collates the deciphered authenticator with the authenticator which has been subjected to the enciphering by said first authenticator enciphering means.

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