This is brief review and rating of Qtum’s “Smart-Contract Value-Transfer Protocols on a Distributed Mobile Application Platform” co-authored by Patrick Dai and Neil Mahi (both from Qtum Fundation) together with Jordan Earls and Alex Norta (Tallin University).
Despite some minor flaws (such, for example, as over-usage of terms like “sociotechnical application suitability” or “formalsemantics language expressiveness”) this work deserves our attention because it explores a rare case of “UTXO-based smartcontract system with a proof-of-stake (PoS) consensus model.”
Very generally, the basic author’s idea is to supplement the actual script language with three opcodes: OP_EXEC and OP_EXEC_ASSIGN (both execute contract bytecode with or without feeding it with data) as well as with OP_TXHASH (is used to ID hash of a currently executed transaction). That allows to extend the traditional UTXO model (input unspent , create new UTXOs outputs, return change to the spender) and to transfer transactions data to EVM where it changes states of smart contracts.
Another work’s deficiency is that despite paper’s name — “Mobile Application Platform” — its authors elaborate very little on how exactly they plan to implement mobile version of this platform and to address multiple issues associated with that types of solution.
Also, it’s difficult to estimate potential vulnerabilities of such “hybrid” systems to various types of attacks without seeing how its actual implementation work for a relatively long period of time. That’s why at this stage I rank “Security” as low as “c+”.
“Engineering” part of this paper, however, yields “b”, more for its audacity than originality. System’s “Transparency” (decentralization), IMHO, deserves strong “a”, specially, if its mobile version will prove my pessimism regarding its “Security” to be misplaced on all accounts. As to network’s “Velocity” — I appreciate the fact that paper’s authors try hard to address the accounts model’s scalability issue. Result: “b+”.
“System”: Security-Velocity-Engineering-Transparency sub-rating: c+b+b+a
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Published at Tue, 07 May 2019 20:05:58 +0000
