Authors:
Shuaijianni Xu
1
;
2
and
Liang Feng Zhang
1
Affiliations:
1
School of Information Science and Technology, ShanghaiTech University, Shanghai, China
;
2
Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai, China
Keyword(s):
Outsourcing Computation, Multi-client Verifiable Computation, Homomorphic Proxy Re-authenticator.
Abstract:
In TCC 2013, Choi, Katz, Kumaresan, and Cid introduced a multi-client verifiable computation (MVC) model for outsourcing computations to cloud. MVC allows multiple non-communicating clients to outsource the computation of a function f over a series of joint inputs to a powerful but untrusted cloud server, ensuring that the input of each client will be secret from all the other entities and rejects any incorrect results from the server. They also proposed a construction of MVC, which heavily depends on fully homomorphic encryption (FHE) and garbled circuits (GCs), thus lacks practical relevance. In this paper, we propose a general transformation from the homomorphic proxy re-authenticator (HPRA) of Derler, Ramacher and Slamanig (FC 2017) to MVC. Our MVC schemes will be significantly more efficient, as long as the underlying HPRA is free of FHE and GCs. By applying the transformation to an HPRA scheme of Derler, Ramacher and Slamanig, we obtained an MVC scheme for computing the linear
combinations of vectors. Our implementation shows that the new MVC scheme is significantly more efficient, both in terms of client computation and server computation. To our best knowledge, this is the first implementable MVC scheme to date.
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