  Permissionless blockchain technology offers numerous potential benefits for
decentralised applications, such as security, transparency, and openness.
BFT-based consensus mechanisms are widely adopted in the permissioned
blockchain to meet the high scalability requirements of the network. Sybil
attacks are one of the most potential threats when applying BFT-based consensus
mechanisms in permissionless blockchain due to the lack of effective
verification mechanisms for participants' identities. This paper presents a
novel endorsement-based bootstrapping protocol with a signature algorithm that
offers a streamlined, scalable identity endorsement and verification process.
This approach effectively safeguards the BFT-based consensus mechanism against
Sybil attacks. Using our proposed method, we have conducted thorough security
analyses and simulation experiments to assess security, robustness, and
scalability advantages in large-scale networks. Our results demonstrate that
the scheme can effectively address the identity verification challenges when
applying BFT-based consensus in a permissionless blockchain.
