Applying Fujisaki-Okamoto to Identity-Based Encryption

  • Peng Yang
  • Takashi Kitagawa
  • Goichiro Hanaoka
  • Rui Zhang
  • Kanta Matsuura
  • Hideki Imai
Part of the Lecture Notes in Computer Science book series (LNCS, volume 3857)

Abstract

The Fujisaki-Okamoto (FO) conversion is widely known to be able to generically convert a weak public key encryption scheme, say one-way against chosen plaintext attacks (OW-CPA), to a strong one, namely, indistinguishable against adaptive chosen ciphertext attacks (IND-CCA). It is not known that if the same holds for identity-based encryption (IBE) schemes, though many IBE and variant schemes are in fact specifically using the FO conversion. In this paper, we investigate this issue and confirm that the FO conversion is generically effective also in the IBE case. However, straightforward application of the FO conversion only leads to an IBE scheme with a loose (but polynomial) reduction. We then propose a simple modification to the FO conversion, which results in considerably more efficient security reduction.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2006

Authors and Affiliations

  • Peng Yang
    • 1
  • Takashi Kitagawa
    • 2
  • Goichiro Hanaoka
    • 2
  • Rui Zhang
    • 1
  • Kanta Matsuura
    • 1
  • Hideki Imai
    • 1
    • 2
  1. 1.Institute of Industrial ScienceUniversity of TokyoTokyoJapan
  2. 2.Research Centre for Information Security (RCIS)National Institute of Advanced Industrial Science and Technology (AIST)TokyoJapan

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