Broadcast Efficient Verifiable Secret Sharing

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Hosseini Beghayi Ravari, Amir | 2015

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 47841 (19)
University: Sharif University of Technology
Department: Computer Engineering
Advisor(s): Izadi, Mohammad
Abstract:
Verifiable secret sharing (VSS) is one of the basic problems in the theory of distributed cryptography and has important role in secure multi-party computation. In this case, it is tried to share a confidential data as secret, between multiple nodes in a distributed system, in the presence of an active adversary that can destroy a number of nodes, such that the secret can be reconstructed with the participation of certain size of honest nodes. There are two types of active adversary; Static and dynamic which the latter can change it’s corrupted nodes among the protocol. VSS protocols have different types of algorithmic complexity and one of these definitions, is the use of broadcast channel that is shared between the nodes. In this thesis, we provide a formal definition of dynamic adversary. We prove a lower bound of alteration period of the dynamic adversary and establish a protocol to deal with this type of adversary. Also we prove a lower bound of broadcast complexity for static adversary
Keywords:
Distributed System ; Broadcast Channel ; Distributed Cryptography ; Verifiable Secret Sharing ; Dynamic Adversary ; Static Adversary