Abstract: Lack of a trusted third party, relatively low node availability and constantly changing membership and network size,make existing multi-secret schemes unsuitable for P2P environment A dynamic multi-secret sharing scheme was proposed for P2P networks. Neither trusted dealers nor secure communication channels are necessary for the proposed scheme, which allows dynamic changes of participants and the system threshold in keeping ciphertext untouched. In the meantime, the participants' identity and public commitments together with system parameters are managed by Byzantine Quorums, which makes it possible to reconstruct a shared secret, add a participant or change the system threshold with only threshold participants online. Additionally,II}based public key cryptosystem and bivariate polynomials are used to reduce message traffic and deal with participant cheating. Altogether, the proposed scheme overcomes the drawbacks of the previous schemes in P2P environment.

Key words: Peer-to-peer network, Multiple secret sharing, ID-based public key cryptosystem, Threshold scheme