Authenticated Key Exchange and Key Encapsulation Without Random Oracles

Tatsuaki Okamoto

Paper 2007/473

Authenticated Key Exchange and Key Encapsulation Without Random Oracles

Tatsuaki Okamoto

Abstract

This paper presents a new paradigm to realize cryptographic primitives such as authenticated key exchange and key encapsulation without random oracles under three assumptions: the decisional Diffie-Hellman (DDH) assumption, target collision resistant (TCR) hash functions and a class of pseudo-random functions (PRFs), $\pi$PRFs, PRFs with pairwise-independent random sources. We propose a (PKI-based) two-pass authenticated key exchange (AKE) protocol that is comparably as efficient as the existing most efficient protocols like MQV and that is secure without random oracles (under these assumptions). Our protocol is shown to be secure in the (currently) strongest security definition, the extended Canetti-Krawczyk (eCK) security definition introduced by LaMacchia, Lauter and Mityagin. We also show that a variant of the Kurosawa-Desmedt key encapsulation mechanism (KEM) using a $\pi$PRF is CCA-secure under the three assumptions. This scheme is secure in a stronger security notion, the chosen public-key and ciphertext attack (CPCA) security, with using a generalized TCR (GTCR) hash function in place of a TCR hash function. The proposed schemes in this paper are validity-check-free and the implication is that combining them with validity-check-free symmetric encryption (DEM) will yield validity-check-free (e.g., MAC-free) CCA-secure hybrid encryption.

Note: I found several errors and typos in the previous version, and corrected them in this revised version.

Metadata

Available format(s): PDF
Category: Public-key cryptography
Publication info: Published elsewhere. This is a revised and full version of the extended abstract published in the proceedings of Asiacrypt 2007 as an invited talk manuscript.
Keywords: key exchange public-key cryptography key encapsulation pseudo-random function
Contact author(s): okamoto tatsuaki @ lab ntt co jp
History: 2007-12-26: revised; 2007-12-19: received; See all versions
Short URL: https://ia.cr/2007/473
License: CC BY

BibTeX

@misc{cryptoeprint:2007/473,
      author = {Tatsuaki Okamoto},
      title = {Authenticated Key Exchange and Key Encapsulation Without Random Oracles},
      howpublished = {Cryptology {ePrint} Archive, Paper 2007/473},
      year = {2007},
      url = {https://eprint.iacr.org/2007/473}
}