Hash-based Proof-of-Work (PoW) used in the Bitcoin Blockchain leads to high
energy consumption and resource wastage. In this paper, we aim to re-purpose
the energy by replacing the hash function with real-life problems having
commercial utility. We propose Chrisimos, a useful Proof-of-Work where miners
are required to find a minimal dominating set for real-life graph instances. A
miner who is able to output the smallest dominating set for the given graph
within the block interval time wins the mining game. We also propose a new
chain selection rule that ensures the security of the scheme. Thus our protocol
also realizes a decentralized minimal dominating set solver for any graph
instance. We provide formal proof of correctness and show via experimental
results that the block interval time is within feasible bounds of hash-based
PoW.Comment: 20 pages, 3 figures. An abridged version of the paper got accepted in
The International Symposium on Intelligent and Trustworthy Computing,
Communications, and Networking (ITCCN-2023) held in conjunction with the 22nd
IEEE International Conference on Trust, Security and Privacy in Computing and
Communications (TrustCom-2023