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Key agreement system, shared-key generation apparatus, and shared-key recovery apparatus

  • US 20040165726A1
  • Filed: 12/02/2003
  • Published: 08/26/2004
  • Est. Priority Date: 12/03/2002
  • Status: Active Grant
First Claim
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1. A key agreement system comprising a shared-key generation apparatus and a shared-key recovery apparatus, each apparatus establishing therein a same shared key in secrecy, wherein the shared-key generation apparatus includes:

  • a seed-value generating unit operable to generate a seed value;

    a first shared-key generating unit operable to generate a verification value and a shared key, from the seed value;

    a first encryption unit operable to encrypt the verification value to generate first encryption information;

    a second encryption unit operable to encrypt the seed value based on the verification value, to generate second encryption information; and

    a transmitting unit operable to transmit the first encryption information and the second encryption information, and the shared-key recovery apparatus includes;

    a receiving unit operable to receive the first encryption information and the second encryption information;

    a first decryption unit operable to decrypt the first encryption information, to generate a first decryption verification value;

    a second decryption unit operable to decrypt the second encryption information based on the first decryption verification value, to generate a decryption seed value;

    a second shared-key generating unit operable to generate a second decryption verification value and a decryption shared key, from the decryption seed value and according to a same method as used in the first shared-key generating unit;

    a judging unit operable to judge, based on the first decryption verification value and the second decryption verification value, whether the decryption shared key should be outputted; and

    an outputting unit operable, when the judging unit has judged affirmatively, to output the decryption shared key.

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