ISSN : 1796-2021
Volume : 3    Issue : 7    Date : December 2008

How to Construct Forward Secure Single-Server, Multi-Server and Threshold-Server Assisted
Signature Schemes Using Bellare-Miner Scheme
Jia Yu, Fanyu Kong, Rong Hao, Dexiang Zhang, and Guowen Li
Page(s): 28-35
Full Text:
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Server-assisted signature plays an important role in all kinds of applications in electronic
commerce. It can be applied to the settings where a user employs public network servers to help
her execute digital signature operations. In this paper, we discuss a problem of how to construct
forward secure single-server, multi-server and threshold-server assisted signature schemes using
Bellare-Miner Scheme and propose three signature schemes. In the single-server assisted
signature scheme, the user (signer) can employ a server to help her produce a signature. In the
multi-server assisted scheme, the number of employed servers is increased to n, therefore, it is
infeasible for an attacker to forge a valid signature if she can’t corrupt all servers and the signer. In
the threshold-server assisted signature scheme, the generation of a valid signature needs the
cooperation of the user and a quorum of servers. The scheme is more robust because the system
can still get the correct signature as soon as no more than threshold servers are corrupted. These
three schemes maintain the forward secure property, that is, even if the current secret key is
exposed, an adaptive chosen-message adversary can’t forge any signature pertaining to previous
time period. Finally, we prove the proposed schemes are correct and forward secure.

Index Terms
digital signature, threshold signature, secret sharing, forward security, security analysis