Paper 2015/371
Constant-Round MPC with Fairness and Guarantee of Output Delivery
S. Dov Gordon and Feng-Hao Liu and Elaine Shi
Abstract
We study the round complexity of multiparty computation with fairness and guaranteed output delivery, assuming existence of an honest majority. We demonstrate a new lower bound and a matching upper bound. Our lower bound rules out any two-round fair protocols in the standalone model, even when the parties are given access to a common reference string (CRS). The lower bound follows by a reduction to the impossibility result of virtual black box obfuscation of arbitrary circuits. Then we demonstrate a three-round protocol with guarantee of output delivery, which in general is harder than achieving fairness (since the latter allows the adversary to force a fair abort). We develop a new construction of a threshold fully homomorphic encryption scheme, with a new property that we call ``flexible'' ciphertexts. Roughly, our threshold encryption scheme allows parties to adapt flexible ciphertexts to the public keys of the non-aborting parties, which provides a way of handling aborts without adding any communication.
Metadata
- Available format(s)
- Publication info
- Preprint. MINOR revision.
- Keywords
- MPCThreshold FHELearning with error
- Contact author(s)
- fenghao @ cs umd edu
- History
- 2015-04-23: received
- Short URL
- https://ia.cr/2015/371
- License
-
CC BY