20,774 research outputs found
On alternative approach for verifiable secret sharing
Secret sharing allows split/distributed control over the secret (e.g. master
key). Verifiable secret sharing (VSS) is the secret sharing extended by
verification capacity.
Usually verification comes at the price. We propose "free lunch", the
approach that allows to overcome this inconvenience.Comment: This is poster that was presented on ESORICS2002 conference in
Zurich. It consists of 4 color pages, with proposal and flowchart
On publicly verifiable secret sharing schemes
Secret sharing allows a dealer to distribute shares of a secret to a set of parties such that only so-called
authorised subsets of these parties can recover the secret, whilst forbidden sets gain at most some restricted
amount of information. This idea has been built upon in verifiable secret sharing to allow parties to verify
that their shares are valid and will therefore correctly reconstruct the same secret. This can then be further
extended to publicly verifiable secret sharing by firstly considering only public channels of communication,
hence imposing the need for encryption of the shares, and secondly by requiring that any party be able to
verify any other parties shares from the public encryption.
In this thesis we work our way up from the original secret sharing scheme by Shamir to examples of various
approaches of publicly verifiable schemes. Due to the need for encryption in private communication,
different cryptographic methods allow for certain interesting advantages in the schemes. We review some
important existing methods and their significant properties of interest, such as being homomorphic or
efficiently verifiable. We also consider recent improvements in these schemes and make a contribution
by showing that an encryption scheme by Castagnos and Laguillaumie allows for a publicly verifiable
secret sharing scheme to have some interesting homomorphic properties. To explore further we look at
generalisations to the recently introduced idea of Abelian secret sharing, and we consider some examples
of such constructions. Finally we look at some applications of secret sharing schemes, and present our own
implementation of Schoenmaker’s scheme in Python, along with a voting system on which it is based
Non-Interactive and Information-Theoretic Secure Publicly Verifiable Secret Sharing
A publicly verifiable secret sharing scheme is more applicable
than a verifiable secret sharing because of the property that the
validity of the shares distributed by the dealer can be verified
by any party. In this paper, we construct a non-interactive and
information-theoretic publicly verifiable secret sharing by a
computationally binding and unconditionally hiding commitment
scheme and zero-knowledge proof of knowledge
On Proactive Verifiable Secret Sharing Schemes
The paper has been presented at the International Conference Pioneers of Bulgarian
Mathematics, Dedicated to Nikola Obreshkoff and Lubomir Tschakaloff , Sofia, July, 2006.
The material in this paper was presented in part at the 11th Workshop on Selected Areas in Cryptography (SAC) 2004This paper investigates the security of Proactive Secret Sharing
Schemes. We first consider the approach of using commitment to 0 in the
renewal phase in order to refresh the player's shares and we present two types
of attacks in the information theoretic case. Then we prove the conditions
for the security of such a proactive scheme. Proactivity can be added also
using re-sharing instead of commitment to 0. We investigate this alternative
approach too and describe two protocols. We also show that both techniques
are not secure against a mobile adversary.
To summarize we generalize the existing threshold protocols to protocols
for general access structure. Besides this, we propose attacks against the
existing proactive verifiable secret sharing schemes, and give modifications
of the schemes that resist these attacks
Distributed Key Generation for the Internet
Although distributed key generation (DKG) has been studied for some time, it has never been examined outside of the synchronous setting. We present the first realistic DKG architecture for use over the Internet. We propose a practical system model and define an efficient verifiable secret sharing scheme in it. We observe the necessity of Byzantine agreement for asynchronous DKG and analyze the difficulty of using a randomized protocol for it. Using our verifiable secret sharing scheme and a leader-based agreement protocol, we then design a DKG protocol for public-key cryptography. Finally, along with traditional proactive security, we also introduce group modification primitives in our system.
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