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ID-based signature, encryption system and encryption method

  • US 20060126832A1
  • Filed: 02/03/2005
  • Published: 06/15/2006
  • Est. Priority Date: 12/09/2004
  • Status: Active Grant
First Claim
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1. A private key generation apparatus in an ID-based signature and encryption system that comprises an encryption apparatus and a decryption apparatus and can use any character string as a public key, wherein:

  • said private key generation apparatus comprises;

    a private key generation and issuing means, which generates public parameters and a master key used in the entire system, and uses said master key for generating a private key corresponding to a user'"'"'s public key in response to a request of a user, to issue the generated private key to said user as a requester; and

    a parameter publication means, which publishes the public parameters generated by the private key generation apparatus; and

    said private key generation apparatus generation and issuing means;

    adds g=e(P, P) (e is a bilinear mapping called a pairing) calculated in advance using a selected element P of a group of order q to said public parameters; and

    defines two elements P1 and P2 of said group as P1=s1P and P2=s2P, using random numbers s1 and s2 as a part of said master key, with s1 and s2 being included in a set Zq* of positive integers less than said order q and relatively prime with q, to calculate (s1+us2)

    1
    P as the private key.

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