Efficient and non-malleable proofs of plaintext knowledge and applications

  • Authors:
  • Jonathan Katz

  • Affiliations:
  • Dept. of Computer Science, University of Maryland, College Park, MD

  • Venue:
  • EUROCRYPT'03 Proceedings of the 22nd international conference on Theory and applications of cryptographic techniques
  • Year:
  • 2003

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Abstract

We describe efficient protocols for non-malleable (interactive) proofs of plaintext knowledge for the RSA, Rabin, Paillier, and El Gamal encryption schemes. We also highlight some important applications of these protocols: - Chosen-ciphertext-secure, interactive encryption. In settings where both parties are on-line, an interactive encryption protocol may be used. We construct chosen-ciphertext-secure interactive encryption schemes based on any of the schemes above. In each case, the improved scheme requires only a small overhead beyond the original, semantically-secure scheme. - Password-based authenticated key exchange. We derive efficient protocols for password-based key exchange in the public-key model [28, 5] whose security may be based on any of the cryptosystems mentioned above. - Deniable authentication. Our techniques give the first efficient constructions of deniable authentication protocols based on, e.g., the RSA or computational Diffie-Hellman assumption. Of independent interest, we consider the concurrent composition of proofs of knowledge; this is essential to prove security of our protocols when run in an asynchronous, concurrent environment.