Provably secure key-updating schemes in identity-based systems

  • Authors:
  • S. Shinozaki;T. Itoh;A. Fujioka;S. Tsujii

  • Affiliations:
  • -;-;-;-

  • Venue:
  • EUROCRYPT '90 Proceedings of the workshop on the theory and application of cryptographic techniques on Advances in cryptology
  • Year:
  • 1991

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Abstract

In this paper, we present Key-Updating Schemes in identity-based (identification or signature) systems, and consider the security of the schemes. We propose two kinds of key-updating schemes, i.e., one is sequential type and the other is parallel type, and show that both schemes are equivalent to each other in a polynomial time sense, i.e., there exists a deterministic polynomial time algorithm that transforms the sequential key-updating scheme to the parallel one, and vice versa. We also show that even if any polynomially many entities conspire to find a secret-key of any other entities, both key-updating schemes are provably secure against polynomially many times key-updating if decrypting RSA is hard.