On the Security of Padding-Based Encryption Schemes --- or --- Why We Cannot Prove OAEP Secure in the Standard Model

  • Authors:
  • Eike Kiltz;Krzysztof Pietrzak

  • Affiliations:
  • Cryptology & Information Security Group, CWI Amsterdam, The Netherlands;Cryptology & Information Security Group, CWI Amsterdam, The Netherlands

  • Venue:
  • EUROCRYPT '09 Proceedings of the 28th Annual International Conference on Advances in Cryptology: the Theory and Applications of Cryptographic Techniques
  • Year:
  • 2009

Quantified Score

Hi-index 0.00

Visualization

Abstract

We investigate the security of "padding-based" encryption schemes in the standard model. This class contains all public-key encryption schemes where the encryption algorithm first applies some invertible public transformation to the message (the "padding"), followed by a trapdoor permutation. In particular, this class contains OAEP and its variants. Our main result is a black-box impossibility result showing that one cannot prove any such padding-based scheme chosen-ciphertext secure even assuming the existence of ideal trapdoor permutations. The latter is a strong ideal abstraction of trapdoor permutations which inherits all security properties of uniform random permutations.