29 research outputs found
Blockchain Application - Case Study on Hyperledger Fabric
Usalduse keskkonna saamiseks kasutatakse kolmandaid osapooli ja nende tarkvara platvorme. Plokiahela tehnoloogia ja nutikaid lepingud on üks võimalus, kuidas välistada kolmas osapool. Üks viimased turule tulnud vabatarkvara platvorme on Hyperledger Fabric - modulaarne süsteem, mis kasutab üldkasutavaid programmeerimskeeli nutikate lepingute keelena. See avardab platvormi kasutamist ettevõtte tarkvara loomisel. Võrdleme platvormi tavapäraste lahendustega ning uurime väljakutseid, mida pakub uus plokiahela põhine süsteem ja selle jaoks loodud nutika leping nimega chaincode. Selle töö käigus realiseeriti parkimiseks mõeldud rakendus, mille nutikas leping on kirjutatud Go programmeerimiskeeles.Töö käigus realiseerisime prototüübi, leidsime lahendused tehnilistele probleemidele, realiseerisime kasutusjuhud.To enable software platform to be used without a third trusted party, one of the possibilities is to use blockchain and smart contracts. One of the latest platform is open-source Hyperledger Fabric, a modular system that uses conventional programming languages for smart contracts. This opens up vast possibilities for using it product centric enterprise systems. In this paper we compare the platform to a conventional solution and study the challenges provided by the smart contract called chaincode. We implement a parking spot application for multisided market using smart contract and Go programming language. In the end we have a working prototype with solutions to technical problems, covering predetermined use cases
Efficient Concurrent Execution of Smart Contracts in Blockchains using Object-based Transactional Memory
This paper proposes an efficient framework to execute Smart Contract
Transactions (SCTs) concurrently based on object semantics, using optimistic
Single-Version Object-based Software Transactional Memory Systems (SVOSTMs) and
Multi-Version OSTMs (MVOSTMs). In our framework, a multi-threaded miner
constructs a Block Graph (BG), capturing the object-conflicts relations between
SCTs, and stores it in the block. Later, validators re-execute the same SCTs
concurrently and deterministically relying on this BG.
A malicious miner can modify the BG to harm the blockchain, e.g., to cause
double-spending. To identify malicious miners, we propose Smart Multi-threaded
Validator (SMV). Experimental analysis shows that the proposed multi-threaded
miner and validator achieve significant performance gains over state-of-the-art
SCT execution framework.Comment: 49 pages, 26 figures, 11 table
NSBchain: A Secure Blockchain Framework for Network Slicing Brokerage
With the advent of revolutionary technologies, such as virtualization and
softwarization, a novel concept for 5G networks and beyond has been unveiled:
Network Slicing. Initially driven by the research community, standardization
bodies as 3GPP have embraced it as a promising solution to revolutionize the
traditional mobile telecommunication market by enabling new business models
opportunities. Network Slicing is envisioned to open up the telecom market to
new players such as Industry Verticals, e.g. automotive, smart factories,
e-health, etc. Given the large number of potential new business players, dubbed
as network tenants, novel solutions are required to accommodate their needs in
a cost-efficient and secure manner. In this paper, we propose NSBchain, a novel
network slicing brokering (NSB) solution, which leverages on the widely adopted
Blockchain technology to address the new business models needs beyond
traditional network sharing agreements. NSBchain defines a new entity, the
Intermediate Broker (IB), which enables Infrastructure Providers (InPs) to
allocate network resources to IBs through smart contracts and IBs to assign and
re-distribute their resources among tenants in a secure, automated and scalable
manner. We conducted an extensive performance evaluation by means of an
open-source blockchain platform that proves the feasibility of our proposed
framework considering a large number of tenants and two different consensus
algorithms
TransEdge: Supporting Efficient Read Queries Across Untrusted Edge Nodes
We propose Transactional Edge (TransEdge), a distributed transaction
processing system for untrusted environments such as edge computing systems.
What distinguishes TransEdge is its focus on efficient support for read-only
transactions. TransEdge allows reading from different partitions consistently
using one round in most cases and no more than two rounds in the worst case.
TransEdge design is centered around this dependency tracking scheme including
the consensus and transaction processing protocols. Our performance evaluation
shows that TransEdge's snapshot read-only transactions achieve an 9-24x speedup
compared to current byzantine systems
Securing the Internet at the Exchange Points
Tese de mestrado, Engenharia Informática (Arquitectura, Sistemas e Redes de Computadores), 2022, Universidade de Lisboa, Faculdade de CiênciasBGP, the border gateway protocol, is the inter-domain routing protocol that glues the
Internet. Despite its importance, it has well-known security problems. Frequently, the
BGP infrastructure is the target of prefix hijacking and path manipulation attacks. These
attacks disrupt the normal functioning of the Internet by either redirecting the traffic,
potentially allowing eavesdropping, or even preventing it from reaching its destination
altogether, affecting availability.
These problems result from the lack of a fundamental security mechanism: the ability
to validate the information in routing announcements. Specifically, it does not authenticate the prefix origin nor the validity of the announced routes. This means that an intermediate network that intercepts a BGP announcement can maliciously announce an IP
prefix that it does not own as theirs, or insert a bogus path to a prefix with the goal to
intercept traffic.
Several solutions have been proposed in the past, but they all have limitations, of
which the most severe is arguably the requirement to perform drastic changes on the
existing BGP infrastructure (i.e., requiring the replacement of existing equipment). In
addition, most solutions require their widespread adoption to be effective. Finally, they
typically require secure communication channels between the participant routers, which
entails computationally-intensive cryptographic verification capabilities that are normally
unavailable in this type of equipment.
With these challenges in mind, this thesis proposes to investigate the possibility to
improve BGP security by leveraging the software-defined networking (SDN) technology
that is increasingly common at Internet Exchange Points (IXPs). These interconnection
facilities are single locations that typically connect hundreds to thousands of networks,
working as Internet “middlemen” ideally placed to implement inter-network mechanisms,
such as security, without requiring changes to the network operators’ infrastructure. Our
key idea is to include a secure channel between IXPs that, by running in the SDN server
that controls these modern infrastructures, avoids the cryptographic requirements in the
routers. In our solution, the secure channel for communication implements a distributed
ledger (a blockchain), for decentralized trust and its other inherent guarantees. The rationale is that by increasing trust and avoiding expensive infrastructure updates, we hope to
create incentives for operators to adhere to these new IXP-enhanced security services