  Decentralized electronic voting solutions represent a promising advancement
in electronic voting. One of the e-voting paradigms, the self-tallying scheme,
offers strong protection of the voters' privacy while making the whole voting
process verifiable. Decentralized smart contract platforms became interesting
practical instantiation of the immutable bulletin board that this scheme
requires to preserve its properties. Existing smart contract-based approaches
employing the self-tallying scheme (such as OVN or BBB-Voting) are only
suitable for a boardroom voting scenario due to their scalability limitation.
The goal of our work is to build on existing solutions to achieve scalability
without losing privacy guarantees and verifiability. We present SBvote, a
blockchain-based self-tallying voting protocol that is scalable in the number
of voters and therefore suitable for large-scale elections. The evaluation of
our proof-of-concept implementation shows that the protocol's scalability is
limited only by the underlying blockchain platform. We evaluated the
scalability of SBvote on two public smart contract platforms -- Gnosis and
Harmony. Despite the limitations imposed by the throughput of the blockchain
platform, SBvote can accommodate elections with millions of voters.
