Multiparty Computation from El Gamal/Paillier Conversion

Koji CHIDA  Hiroaki KIKUCHI  Keiichi HIROTA  Gembu MOROHASHI  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E92-A    No.1    pp.137-146
Publication Date: 2009/01/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E92.A.137
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Secure Protocol
encryption conversion,  multiparty protocol,  homomorphic encryption,  privacy-preserving statistical computation,  

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We propose a protocol for converting the encryption function of a ciphertext into another encryption function while keeping the corresponding message secret. The proposed protocol allows conversions of the El Gamal and Paillier cryptosystems and has the potential to design an efficient multiparty protocol intended for circuits consisting of arithmetic and logical operations. We clarify the condition of circuits such that the multiparty protocol based on the proposed protocol provides better performance than previous approaches. In addition, we introduce some privacy-preserving statistical computations as an effective application of the proposed protocol.