Paper 2008/534
Somewhat Non-Committing Encryption and Efficient Adaptively Secure Oblivious Transfer
Juan A. Garay, Daniel Wichs, and Hong-Sheng Zhou
Abstract
Designing efficient cryptographic protocols tolerating adaptive
adversaries, who are able to corrupt parties on the fly as the
computation proceeds, has been an elusive task. Indeed, thus far no
\emph{efficient} protocols achieve adaptive security for general
multi-party computation, or even for many specific two-party tasks
such as oblivious transfer (OT). In fact, it is difficult and
expensive to achieve adaptive security even for the task of
\emph{secure communication}, which is arguably the most basic task
in cryptography.
In this paper we make progress in this area. First, we introduce a
new notion called \emph{semi-adaptive} security which is slightly
stronger than static security but \emph{significantly weaker than
fully adaptive security}. The main difference between adaptive and
semi-adaptive security is that, for semi-adaptive security, the
simulator is not required to handle the case where \emph{both}
parties start out honest and one becomes corrupted later on during
the protocol execution. As such, semi-adaptive security is much
easier to achieve than fully adaptive security. We then give a
simple, generic protocol compiler which transforms any
semi-adaptively secure protocol into a fully adaptively secure one.
The compilation effectively decomposes the problem of adaptive
security into two (simpler) problems which can be tackled
separately: the problem of semi-adaptive security and the problem of
realizing a weaker variant of secure channels.
We solve the latter problem by means of a new primitive that we call
{\em somewhat non-committing encryption} resulting in significant
efficiency improvements over the standard method for realizing
(fully) secure channels using (fully) non-committing encryption.
Somewhat non-committing encryption has two parameters: an
equivocality parameter
Metadata
- Available format(s)
-
PDF
- Category
- Cryptographic protocols
- Publication info
- Published elsewhere. Unknown where it was published
- Contact author(s)
- hszhou @ cse uconn edu
- History
- 2009-04-15: last of 3 revisions
- 2008-12-19: received
- See all versions
- Short URL
- https://ia.cr/2008/534
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2008/534, author = {Juan A. Garay and Daniel Wichs and Hong-Sheng Zhou}, title = {Somewhat Non-Committing Encryption and Efficient Adaptively Secure Oblivious Transfer}, howpublished = {Cryptology {ePrint} Archive, Paper 2008/534}, year = {2008}, url = {https://eprint.iacr.org/2008/534} }