14 research outputs found
Efficient Threshold Secret Sharing Schemes Secure against Rushing Cheaters
In this paper, we consider three very important issues namely detection, identification and robustness of -out-of- secret sharing schemes against rushing cheaters who are allowed to submit (possibly forged) shares {\em after} observing shares of the honest users in the reconstruction phase. Towards this we present five different schemes. Among these, first we present two -out-of- secret sharing schemes, the first one being capable of detecting cheaters such that and the second one being capable of detecting cheaters such that , where denotes the set of all possible secrets, denotes the successful cheating probability of cheaters and denotes set all possible shares. Next we present two -out-of- secret sharing schemes, the first one being capable of identifying rushing cheaters with share size that satisfies . This is the first scheme whose size of shares does not grow linearly with but only with , where is the number of participants. For the second one, in the setting of public cheater identification, we present an efficient optimal cheater resilient -out-of- secret sharing scheme against rushing cheaters having the share size . The proposed scheme achieves {\em flexibility} in the sense that the security level (i.e. the cheater(s) success probability) is independent of the secret size. Finally, we design an efficient robust secret sharing secure against rushing adversary with optimal cheater resiliency.
Each of the five proposed schemes has the smallest share size having the mentioned properties among the existing schemes in the respective fields
Secure Modulo Zero-Sum Randomness as Cryptographic Resource
We propose a new cryptographic resource, which we call
modulo zero-sum randomness, for several cryptographic tasks.
The modulo zero-sum randomness
is distributed randomness among parties,
where
are independent of each other but holds.
By using modulo zero-sum randomness, we show that
multi-party secure computation for some additively homomorphic functions
is efficiently realized without the majority honest
nor secure communication channels (but public channel). We also
construct secret sharing protocols without secure communication channels.
Moreover, we consider a new cryptographic task
multi-party anonymous authentication, which is realized by
modulo zero-sum randomness.
Furthermore, we discuss how to generate modulo zero-sum randomness
from some information theoretic assumption. Finally, we give a
quantum verification protocol of testing the property of
modulo zero-sum randomness
P2DEX: Privacy-Preserving Decentralized Cryptocurrency Exchange
Cryptocurrency exchange services are either trusted central entities that have been routinely hacked (losing over 8 billion USD), or decentralized services that make all orders public before they are settled. The latter allows market participants to ``front run\u27\u27 each other, an illegal operation in most jurisdictions. We extend the ``Insured MPC\u27\u27 approach of Baum et al. (FC 2020) to construct an efficient universally composable privacy preserving decentralized exchange where a set of servers run private cross-chain exchange order matching in an outsourced manner, while being financially incentivised to behave honestly. Our protocol allows for exchanging assets over multiple public ledgers, given that users have access to a ledger that supports standard public smart contracts. If parties behave honestly, the on-chain complexity of our construction is as low as that of performing the transactions necessary for a centralized exchange. In case malicious behavior is detected, users are automatically refunded by malicious servers at low cost. Thus, an actively corrupted majority can only mount a denial-of-service attack that makes exchanges fail, in which case the servers are publicly identified and punished, while honest clients do not to lose their funds. For the first time in this line of research, we report experimental results on the MPC building block, showing the approach is efficient enough to be used in practice
Semantic discovery and reuse of business process patterns
Patterns currently play an important role in modern information systems (IS) development and their use has mainly been restricted to the design and implementation phases of the development lifecycle. Given the increasing significance of business modelling in IS development, patterns have the potential of providing a viable solution for promoting reusability of recurrent generalized models in the very early stages of development. As a statement of research-in-progress this paper focuses on business process patterns and proposes an initial methodological framework for the discovery and reuse of business process patterns within the IS development lifecycle. The framework borrows ideas from the domain engineering literature and proposes the use of semantics to drive both the discovery of patterns as well as their reuse