In the bare public-key model (BPK in short), each veri er is assumed to have deposited a public key in a le that is accessible by all users at all times. In this model, introduced by Canetti et al. [STOC 2000], constant-round black-box concurrent and resettable zero knowledge is possible as opposed to the standard model for zero knowledge.

In this paper, we present both practical and general 4-round concurrent and resettable zeroknowledge arguments with concurrent soundness in the bare public-key (BPK) model. To our knowledge, our result is the first work that achieves concurrent soundness for ZK protocols in the BPK model and stands for the current state-of-the-art of concurrent zero-knowledge with setup assumptions.