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Member certificate acquiring device, member certificate issuing device, group signing device, and group signature verifying device

  • US 8,074,067 B2
  • Filed: 01/16/2006
  • Issued: 12/06/2011
  • Est. Priority Date: 02/10/2005
  • Status: Active Grant
First Claim
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1. A group signing device, which is input with a group public key, a tracking public key, a member certificate, a member secret key, and a message and which outputs a group signature for said message, said group signing device comprising:

  • an encryption device for creating an encrypted text in which part of member evidence generated from said member secret key is encrypted by said tracking public key from;

    a) said group public key including a description for four groups;

    (1) group 1, group 2, group T, and group E, of a same order number,(2) a description of bilinear mapping from said group 1 and said group 2 to said group T,(3) respective generators of said group 1, said group 2, said group T, and said group E, and(4) a signature public key of a signature scheme utilizing said group 1, said group 2, and said group T;

    b) said tracking public key comprising an element of said group E; and

    c) said member secret key; and

    a knowledge-proof-statement generating device comprising a processor which generates a knowledge proof statement which is data for proving that a secret key encrypted into said encrypted text and a signature for said secret key can be calculated from input data, wherein said group signature to be output includes said knowledge proof statement generated by said knowledge-proof-statement generating device, andwherein said group E is a group different from said group 1, said group 2, and said group T for solving a Diffie-Hellman discrimination problem.

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