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Signature-generation method, signature-verification method, public-key distribution method, and information-processing apparatus

  • US 7,685,429 B2
  • Filed: 09/29/2005
  • Issued: 03/23/2010
  • Est. Priority Date: 10/05/2004
  • Status: Expired due to Fees
First Claim
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1. A signature-generation method comprising:

  • an input step of inputting a message to be signed;

    a hash process step, performed by a processor, of performing a hash process on the message to obtain fixed-length data;

    an addition step of adding nth padding data to the fixed-length data obtained by performing the hash process on the message, wherein n is an integer from 1 to N, and N is equal to or greater than 2;

    a generation step of generating nth signature data from data obtained by performing the hash process on the message by using nth private key, wherein key length of the nth private key is longer than key length of (n+1)th private key and;

    an output step of outputting first padding data through nth padding data, nth signature data, and the message,wherein the hash process step, the addition step, and the generation step are repeated a predetermined N number of times, and (n−

    1)th signature data generated in the generation step is the nth padding data added to the fixed-length data in the addition step, andwherein the message, the padding data, and the signature data are coupled to one another so that at least one public-key certificate is generated, and where the addition step and the generation step are performed the predetermined N number of times, algorithms used for the hash function vary every time the addition step and the generation step are performed, algorithms used for a public-key cryptosystem vary every time the addition step and the generation step are performed, and key length used for the public-key cryptosystem decreases every time the addition step and the generation step are performed.

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