SCIS 2022
2022 Symposium on
Cryptography and Information Security
Osaka, Japan & Online, Jan. 18 – 21, 2022
The Institute of Electronics,
Information and Communication Engineers

Copyright c 2022 The Institute of Electronics,
Information and Communication Engineers

Conclave: A Collective Stake Pool Protocol
Dimitris Karakostas ∗Aggelos Kiayias ∗Mario Larangeira †Keywords: Proof-of-Stake, Blockchain, Consensus, Delegation, Threshold ECDSA.

Abstract
Proof-of-Stake (PoS) distributed ledgers are the mostcommon alternative to Bitcoin’s Proof-of-Work (PoW)
paradigm, replacing hardware dependency with stake,i.e., assets that a party controls. Similar to PoW’s mining pools, PoS’s stake pools, i.e., collaborative entities
comprising of multiple stakeholders, allow a party toearn rewards more regularly, compared to participating on an individual basis. However, stake pools tend
to increase centralization, since they are typically managed by a single party that acts on behalf of the pool’smembers. In this work we propose Conclave, a formal
design of a Collective Stake Pool, i.e., a decentralized
pool with no single point of authority. Among Conclave’s building blocks is a weighted threshold signaturescheme (WTSS); we define the WTSS ideal functionality — which is of independent interest — and propose
two threshold ECDSA based constructions which enable (1) fast trustless setup and (2) identifiable aborts.
The Delegated PoS. Bitcoin combined PoW, toprevent sybil attacks, with financial rewards, to incentivize participation. However, PoW’s deficiencies, particularly its egregious environmental cost,1 have driven
research on alternative designs, most prominently PoS,
which removes hardware and energy requirements altogether and internalizes sybil resilience by relying onparties’ stake, i.e., the assets that they own. Interestingly, both PoW and PoS are economies of scale, whofavor parties with large amounts of participating power.
One reason is poorly-designed incentives, resulting in
disproportionate power accumulation [2, 4]. Anotheris temporal discounting, i.e., the tendency to disfavorrare or delayed rewards [5]. In contrast, accumulating
the power of multiple small parties in “pools” yields a∗Universityof
Edinburgh
andIOHK,{dimitris.karakostas@,akiayias@inf.}ed.ac.uk
and{dimitris.karakostas,aggelos.kiayias}@iohk.io.
†TokyoInstituteofTechnology
andIOHK,
mario@c.titech.ac.jp / mario.larangeira@iohk.io.
This work is supported by JSPS KAKENHI No. JP21K11882.
1 The carbon footprint of: i) a single Bitcoin transaction is equivalent to 1, 202, 422 VISA transactions; ii) the total Bitcoin network is comparable to Sweden. (https://digiconomist.net/
bitcoin-energy-consumption; May 2021)

steadier reward. As a result, PoS usually favors delegation to stake pools [1, 3] over “pure” PoS, i.e., notdelegated. Finally, the ledger’s performance and security are often better under fewer participants. Namely,
PoS requires constant online participants since abstaining is a security hazard, which is more easily guaranteed
within a small set of dedicated delegates.
The Collective Stake Pool. A major drawback ofexisting stake pools is that they are typically managed
by a single party, the operator. This party participatesin consensus, claims the rewards offered by the system,and then distributes them among the pool’s members(after subtracting a fee). However, the operator is asingle point of failure. In this work, we explore a moredesirable design, which allows players to jointly form acollective pool, i.e., the Conclave. This design assumes
no single operator, minimizing excess fees, trust and security concerns, altogether. Collective stake pools also
promote a more fair and decentralized environment.

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