Paper 2019/456 Original: eprint.iacr.org/2019/456 ↗

UniqueChain: A Fast, Provably Secure Proof-of-Stake Based Blockchain Protocol in the Open Setting

Abstract

We present UniqueChain, a proof-of-stake based blockchain protocol that is secure against a mildly adaptive adversary in open setting, where newly joining parties can be initialized securely without any additional trusted assumptions. What's more, UniqueChain provides secure best local chains for existing honest parties and achieves fast messages (transactions) confirmation. Security of protocol holds if majority of overall stakes are controlled by honest parties. To achieve the above guarantees, we formalize a secure bootstrapping mechanism for new parties, a best local chain selection rule for existing honest parties and propose a new form of two-chain structure that realizes uniqueness of the chains, which contain messages, held by honest parties. Further, we prove that $UniqueChain$ satisfies security properties as chain growth, chain quality, common prefix and soundness, and two additional properties as uniqueness and high efficiency.