@article {16778,
	title = {Partial Pre-Image Attack on Proof-of-Work based Blockchains},
	journal = {Blockchain: Research and Applications},
	year = {2024},
	abstract = {Blockchain (BC) is the type of distributed ledger technology that consists of a growing list of records, called blocks, that are securely linked together using cryptography. Each BC-based solution deploys a specific consensus algorithm that guarantees the consistency of the ledger over time. The most famous, and yet claimed to be the most secure, is the Proof-of-Work (PoW) consensus algorithm. In this paper,we revisit the fundamental calculations and assumptions of this algorithm, originally presented in the Bitcoin white paper. We break down its claimed calculations, in order to better understand the underlying assumptions of the proposal. We also propose a novel formalization model of the PoW mining problem using the Birthday paradox. We utilize this model to formalize and analyze Partial Pre-Image attacks on PoW-based BCs, with formal analysis that confirmed the experimental results and the previously proposed implications. We build on those analyses and propose new concepts for benchmarking the security of PoW-based systems, including Critical Difficulty and Critical Difficulty per given portion. Our calculations resulted in several important findings including the profitability of launching Partial Pre-Image attacks on PoW-based BCs, once the mining puzzle difficulty reaches a given threshold. Specifically, for any compromised portion of the network (q < 0.5; honest majority assumption still holds), the attack was formally proven profitable, once the PoW mining puzzle difficulty reaches 56 leading zeros.},
	keywords = {Blockchain, Hash functions, Partial pre-image attack, Proof-of-Work, Security},
	doi = {10.1016/j.bcra.2024.100194},
	url = {https://www.sciencedirect.com/science/article/pii/S2096720924000071},
	author = {Baniata, Hamza and Kert{\'e}sz, Attila}
}
@article {16780,
	title = {PriFoB: A Privacy-aware Fog-enhanced Blockchain-based system for Global Accreditation and Credential Verification},
	journal = {Journal of Network and Computer Applications},
	volume = {205},
	year = {2022},
	abstract = {Trusted online credential management solutions are needed for instant and practical verification. Most of the available frameworks targeting this field violate the privacy of end-users or lack sufficient solutions in terms of security and Quality-of-Service (QoS). In this paper, we propose a Privacy-aware Fog-enhanced Blockchain-based online credential management solution, namely PriFoB. Our proposed solution adopts a public permissioned Blockchain model with different reliable encryption schemes, standardized Zero-Knowledge-Proofs (ZKPs) and Digital Signatures (DSs) within a Fog{\textendash}Blockchain integrated framework, which is also GDPR compliant. We deploy both the Proof-of-Authority (PoA) and the Signatures-of-Work (SoW) consensus algorithms for efficient and secure handling of Verifiable Credentials (VCs) and global accreditation of VC issuers, respectively. Furthermore, we propose a novel three-dimensional DAG-based model of the Distributed Ledger (3DDL), and provide a ready-to-deploy PriFoB implementation. We discuss insights regarding the utilization and the potential of PriFoB, and evaluate it in terms of security, privacy, latency, throughput and power utilization. We analyze its performance in different layers of a Fog-enabled cloud architecture with simulation and emulation, and we show that PriFoB outperforms several Blockchain-based solutions utilizing Ethereum, Hyperledger Fabric, Hyperledger Besu and Hyperledger Indy platforms.},
	keywords = {Blockchain, Credential Verification, fog computing, Global accreditation, Privacy, Self Sovereign Identity (SSI)},
	issn = {1084-8045},
	doi = {https://doi.org/10.1016/j.jnca.2022.103440},
	url = {https://www.sciencedirect.com/science/article/pii/S1084804522000935},
	author = {Hamza Baniata and Attila Kert{\'e}sz}
}
@conference {Pflanzner2016282,
	title = {Performance analysis of an openstack private cloud},
	booktitle = {CLOSER 2016 - Proceedings of the 6th International Conference on Cloud Computing and Services Science},
	volume = {2},
	year = {2016},
	note = {cited By 1},
	pages = {282-289},
	keywords = {select:cloud},
	url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979544396\&partnerID=40\&md5=92478a567bf7de658d9b6c70ec903b24},
	author = {Pflanzner, T. and Tornyai, R. and Gibizer, B. and Schmidt, A. and Attila Kert{\'e}sz}
}
@article {Kertesz201641,
	title = {A Pliant-based Virtual Machine Scheduling Solution to Improve the Energy Efficiency of IaaS Clouds},
	journal = {Journal of Grid Computing},
	volume = {14},
	number = {1},
	year = {2016},
	note = {cited By 0},
	pages = {41-53},
	doi = {10.1007/s10723-015-9336-9},
	url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84928623040\&doi=10.1007\%2fs10723-015-9336-9\&partnerID=40\&md5=d9b31d1217fd1528c28baa3fdff354be},
	author = {Attila Kert{\'e}sz and J D Dombi and Benyi, A.}
}
