RSA-OAEP Is Secure under the RSA Assumption

  • Authors:
  • Eiichiro Fujisaki;Tatsuaki Okamoto;David Pointcheval;Jacques Stern

  • Affiliations:
  • NTT Labs, 1-1 Hikarino-oka, Yokosuka-shi 239-0847, Japan;NTT Labs, 1-1 Hikarino-oka, Yokosuka-shi 239-0847, Japan;Département d’Informatique, ENS – CNRS, 45 rue d’Ulm, 75230 Paris Cedex 05, France;Département d’Informatique, ENS – CNRS, 45 rue d’Ulm, 75230 Paris Cedex 05, France

  • Venue:
  • Journal of Cryptology
  • Year:
  • 2004

Quantified Score

Hi-index 0.06

Visualization

Abstract

Recently Victor Shoup noted that there is a gap in the widely believed security result of OAEP against adaptive chosen-ciphertext attacks. Moreover, he showed that, presumably, OAEP cannot be proven secure from the one-wayness of the underlying trapdoor permutation. This paper establishes another result on the security of OAEP. It proves that OAEP offers semantic security against adaptive chosen-ciphertext attacks, in the random oracle model, under the partial-domain one-wayness of the underlying permutation. Therefore, this uses a formally stronger assumption. Nevertheless, since partial-domain one-wayness of the RSA function is equivalent to its (full-domain) onewayness, it follows that the security of RSA-OAEP can actually be proven under the sole RSA assumption, although the reduction is not tight.