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Detecting the community structure and predicting the change of community structure is an important research topic in social network research. Focusing on the importance of nodes and the importance of their neighbors and the adjacency information, this article proposes a new evaluation method of node importance. The proposed overlapping community detection algorithm (ILE) uses the random walk to select the initial community and adopts the adaptive function to expand the community. It finally optimizes the community to obtain the overlapping community. For the overlapping communities, this article analyzes the evolution of networks at different times according to the stability and differences of social networks. Seven common community evolution events are obtained. The experimental results show that our algorithm is feasible and capable of discovering overlapping communities in complex social network efficiently.

Group signature can provide the privacy-preserving authentication mechanism for the blockchain. In the traditional blockchain privacy-preserving scheme based on the group signature, there is only one group manager to revoke the anonymity. Thus, the traditional scheme will have single point of failure and key escrow problems. To solve these problems, we propose a privacy-preserving scheme in the blockchain based on the group signature with multiple managers. Our scheme is constructed based on bilinear pairing and the technique of distributed key generation. Finally, we analyze the application of the proposed scheme in the field of blockchain-based provable data possession (PDP), as well as the correctness and security of the scheme.

Identification schemes support that a prover who holding a secret key to prove itself to any verifier who holding the corresponding public key. In traditional identity-based identification schemes, there is a key generation center to generate all users’ secret keys. This means that the key generation center knows all users’ secret key, which brings the key escrow problem. To resolve this problem, in this work, we define the model of identity-based identification without a trusted party. Then, we propose a multi-authority identity-based identification scheme based on bilinear pairing. Furthermore, we prove the security of the proposed scheme in the random oracle model against impersonation under passive and concurrent attacks. Finally, we give an application of the proposed identity-based identification scheme to blockchain.

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