Journal of Cryptology

, Volume 17, Issue 2, pp 81–104

RSA-OAEP Is Secure under the RSA Assumption


DOI: 10.1007/s00145-002-0204-y

Cite this article as:
Fujisaki, E., Okamoto, T., Pointcheval, D. et al. J Cryptol (2004) 17: 81. doi:10.1007/s00145-002-0204-y


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.

Public-key encryptionProvable securityRSAOAEP

Copyright information

© Springer-Verlag 2002

Authors and Affiliations

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