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Front Matter, Table of Contents, Preface, Committees, List of Authors
No full textFront Matter, Table of Contents, Preface, Committees, List of Author
LIPIcs, Volume 46, OPODIS'15, Complete Volume
No full textLIPIcs, Volume 46, OPODIS'15, Complete Volum
Cryptographic Tools for Blockchains
No full textCryptography plays a fundamental role in blockchain systems, ensuring security and integrity at multiple levels. Blocks are linked through cryptographic hash functions, and consensus mechanisms, such as proof-of-work, rely on these functions for validation. Transactions require authorization via digital signatures, while newer blockchain models incorporate advanced cryptographic tools, such as verifiable random functions for proof-of-stake and zero-knowledge proofs for private yet verifiable transactions. This chapter explores the cryptographic schemes essential to modern blockchain systems, discussing their role and security foundations. It follows the standard approach of defining security through asymptotic complexity and probabilistic polynomial time (PPT) adversaries. Most cryptographic schemes depend on hard mathematical problems, including RSA factorization and the discrete logarithm problem, which form the basis for many encryption and authentication protocols
Public vs Private Blockchains lineage storage
Get PDFThis paper reports the experimental results related to lineage event storage via smart contracts deployed on private and public blockchain. In our experiments we measure the following three metrics: the cost to deploy the storage smart contract on the blockchain, which measures the initial expenditure, typically in gas units, required to deploy the smart contract that facilitates lineage event storage, then the time and gas costs needed to store a lineage event. We investigated both single and multi-clients scenarios. We considered the following public blockchains: Hedera, Fantom, Harmony Shard0, Polygon Amoy, Ethereum Sepolia, Optimism Sepolia, Klaytn Baobab and Arbitrum Sepolia. Furthermore, we investigate the performances of Hyperledger Besu with different consensus algorithms as private blockchains
Mobile Byzantine Agreement in a Trusted World
Get PDFIn this paper, we address the Byzantine Agreement problem in synchronous systems where Byzantine agents can move from process to process, corrupting their host.
We focus on three representative models: \emph{Garay\u27s}, \emph{Bonnet\u27s} and \emph{Buhrman\u27s} models.
In \emph{Garay\u27s model} when a process has been left by the Byzantine, it is in the \emph{cured} state and it is aware of its condition and thus can remain silent for a round to prevent the dissemination of wrong information.
In \emph{Bonnet\u27s model} a cured process may send messages (based on a state corrupted by the malicious agent), however it will behave correctly in the way it sends those messages: i.e., send messages according to the algorithm.
In \emph{Buhrman\u27s model} Byzantine agents move together with the message.
It has been shown that in order to solve Byzantine Agreement in the \emph{Garay\u27s model} at least processors are needed, for \emph{Bonnet\u27s model} at least processors are needed, while for \emph{Buhrman\u27s model} at least processors are needed.
In this paper we target to increase the tolerance to mobile Byzantines by integrating a trusted counter abstraction to the above models. This abstraction prevents nodes to equivocate. In the new models we prove that at least , respectively , and processors are needed to tolerate mobile Byzantine agents. Furthermore, we propose novel Mobile Byzantine Agreement algorithms that match these new lower bounds for \emph{Garay\u27s}, \emph{Bonnet\u27s} and \emph{Buhrman\u27s} models
Distributed Blockchain Price Oracle
Get PDFBlockchain oracles are systems that connect blockchains with
the outside world by interfacing with external data providers. They provide
decentralized applications with the external information needed for
smart contract execution. In this paper, we focus on decentralized price
oracles, which are distributed systems that provide exchange rates of
digital assets to smart contracts. They are the cornerstone of the safety
of some decentralized finance applications such as stable coins or lending
protocols. They consist of a network of nodes called oracles that gather
information from off-chain sources such as an exchange market’s API and
feed it to smart contracts. Among the desired properties of a price oracle
system are low latency, availability, and low operating cost. Moreover,
they should overcome constraints such as having diverse data sources
which is known as the freeloading problem or Byzantine failures.
In this paper, we define the distributed price oracle problem and present
PoWacle, the first asynchronous decentralized oracle protocol that copes
with Byzantine behavior
Composable Dynamic Secure Emulation
Get PDFThis work extends the composable secure-emulation of Canetti et al. to dynamic settings. Our work builds on top of dynamic probabilistic I/O automata, a recent framework introduced to model dynamic probabilistic systems. Our extension is an important tool towards the formal verification of protocols combining probabilistic distributed systems and cryptography in dynamic settings (e.g. blockchains, secure distributed computation, cybersecure distributed protocols etc)
Probabilistic Dynamic Input Output Automata (Extended Version)
No full textWe present probabilistic dynamic I/O automata, a framework to model dynamic probabilistic systems. Our work extends dynamic I/O Automata formalism of Attie & Lynch to probabilistic setting. The original dynamic I/O Automata formalism included operators for parallel composition, action hiding, action renaming, automaton creation, and behavioral sub-typing by means of trace inclusion. They can model mobility by using signature modification. They are also hierarchical: a dynamically changing system of interacting automata is itself modeled as a single automaton.
Our work extends to probabilistic settings all these features. Furthermore, we prove necessary and sufficient conditions to obtain the implementation monotonicity with respect to automata creation and destruction. Our construction uses a novel proof technique based on homomorphism that can be of independent interest.
Our work lays down the foundations for extending composable secure-emulation of Canetti et al. to dynamic settings, an important tool towards the formal verification of protocols combining probabilistic distributed systems and cryptography in dynamic settings (e.g. blockchains, secure distributed computation, cybersecure distributed protocols etc)
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