Paper 2026/406
Putting the OPTI in Round Optimal IA-MPC in the Plain Model
, Silence Laboratories, University of Amsterdam, Aarhus University, Aarhus UniversityAbstract
We advance the study of best-possible security guarantees of two-round secure multiparty computation in the plain model. While Goel et al. (TCC '21) showed the infeasibility of Identifiable Abort in two rounds in the plain model with a standard honest majority (i.e. $t < n/2$), the effect of relaxing the setting to an honest supermajority has not been established. In this work, we close this gap. When $t < n/3$, we show that two rounds are sufficient to achieve identifiable abort. Notably, ours is the first two-round general-purpose MPC construction in the plain model tolerating more than one corruption that achieves a guarantee stronger than unanimous abort. We obtain our construction via a new compiler that lifts any protocol with unanimous abort to one that achieves identifiable abort. A core building block for our compiler is Oblivious Public Transfer with Intermediaries (OPTI), a new primitive that we introduce which may be of independent interest.
Metadata
- Available format(s)
-
PDF
- Category
- Cryptographic protocols
- Publication info
- A major revision of an IACR publication in ASIACRYPT 2026
- Keywords
- Secure Multi-Party ComputationTwo-round MPCPlain ModelIdentifiable Abort
- Contact author(s)
-
yash @ ykondi net
d ravi @ uva nl
jsternad @ cs au dk
sophia yakoubov @ cs au dk - History
- 2026-10-07: revised
- 2026-02-27: received
- See all versions
- Short URL
- https://ia.cr/2026/406
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2026/406,
author = {Yashvanth Kondi and Divya Ravi and Jure Sternad and Sophia Yakoubov},
title = {Putting the {OPTI} in Round Optimal {IA}-{MPC} in the Plain Model},
howpublished = {Cryptology {ePrint} Archive, Paper 2026/406},
year = {2026},
url = {https://eprint.iacr.org/2026/406}
}
