IX. Discussion and Future Work
XI. CONCLUSIONIn this work, we started with an overview of DAG-oriented consensus protocols for Proof-of-Work blockchains, which promise to increase the transaction throughput by using random transaction selection strategy. We formulated a hypothesis that DAG protocols using the random strategy can be exploited by attackers not respecting such a strategy and instead selecting transaction based on the fees (i.e., greedy strategy), which can lead to deterioration of the overall transaction throughput. We made a game theoretical analysis of concerned DAG-oriented protocols and concluded that the random strategy, as proposed in these protocols, does not constitute a Nash equilibrium since honest players enable the greedy player to “parasite” on the system. This is contradictory result to Inclusive paper [26], which does not assume that multiple greedy miners can form a mining pool.
\ We conducted several experiments on simplified network topology as well as complex network using an abstracted DAG-PROTOCOL. In our experiments, we analyzed the impact of greedy miners who deviated from the modeled DAG protocol by selecting transactions based on the highest fee. We demonstrated that greedy miners have a significant advantage over honest miners in terms of profit maximization. Moreover, we showed that greedy miners have a detrimental impact on transaction throughput and have the incentive to form a mining pool, exacerbating the decentralization of the assumed consensus protocols.
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\ APPENDIX - GLOSSARY
\
A A block in the DAG-PROTOCOL
\
G Greedy strategy, choosing transactions with the highest fees
\
H Honest strategy, choosing random transactions
\
γ Discount function in PHANTOM
\
κ Adversarial mining power
\
λ Block creation time
\
G The number of greedy miners
\
τ Network propagation delay of blocks
\
c Gap parameter in PHANTOM
\
e Euler’s number
\
t Time
\
RTS Random Transaction Selection
\
DAG Directed Acyclic Graph
\
MNE Mixed Nash Equilibrium
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PNE Pure Nash Equilibrium
\
PoW Proof of Work
\
SPNE Subgame Perfect Nash Equilibrium
\
:::info Authors:
(1) Martin Peresıni, Brno University of Technology, Faculty of Information Technology ([email protected]);
(2) Ivan Homoliak, Brno University of Technology, Faculty of Information Technology ([email protected]);
(3) Federico Matteo Bencic, University of Zagreb, Faculty of Electrical Engineering and Computing ([email protected]);
(4) Martin Hruby, Brno University of Technology, Faculty of Information Technology ([email protected]);
(5) Kamil Malinka, Brno University of Technology, Faculty of Information Technology ([email protected]).
:::
:::info This paper is available on arxiv under CC BY 4.0 DEED license.
:::
\
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