PUMTD:Privacy-Preserving User-Profile Matching Protocol in Social Networks

User profile matching can establish social relationships between different users in the social network.If the user profile is matched in plaintext,the user's privacy might face a security challenge.Although there exist some schemes realizing privacypreserving user profile matching,the resource-limited users or social service providers in these schemes need to take higher computational complexity to ensure the privacy or matching of the data.To overcome the problems,a novel privacy-preserving user profile matching protocol in social networks is proposed by using t-out-of n servers and the bloom filter technique,in which the computational complexity of a user is reduced by applying the Chinese Remainder Theorem,the matching users can be found with the help of any t matching servers,and the privacy of the user profile is not compromised.Furthermore,if at most t-1 servers are allowed to collude,our scheme can still fulfill user profile privacy and user query privacy.Finally,the performance of the proposed scheme is compared with the other two schemes,and the results show that our scheme is superior to them.

tsrCert:Traceable Self-Randomization Certificate and Its Application to Blockchain Supervision

Traditional public key infrastructure(PKI)only provides authentication for network communication,and the standard X.509 certificate used in this architecture reveals the user’s identity.This lack of privacy protection no longer satisfies the increasing demands for personal privacy.Though an optimized anonymous PKI certificate realizes anonymity,it has the potential to be abused due to the lack of identity tracking.Therefore,maintaining a balance between user anonymity and traceability has become an increasing requirement for current PKI.This paper introduces a novel traceable self-randomization certificate authentication scheme based on PKI architecture that achieves both anonymity and traceability.We propose a traceable self-randomization certificate authentication scheme based on the short randomizable signature.Specifically,certificate users can randomize the initial certificate and public key into multiple anonymous certificates and public keys by themselves under the premise of traceability,which possesses lower computational complexity and fewer interactive operations.Users can exhibit different attributes of themselves in different scenarios,randomizing the attributes that do not necessarily need to be displayed.Through security and performance analysis,we demonstrate the suitability of the improved PKI architecture for practical applications.Additionally,we provide an application of the proposed scheme to the permissioned blockchain for supervision.

Reaching consensus for membership dynamic in secret sharing and its application to cross-chain

The communication efficiency optimization,censorship resilience,and generation of shared randomness are inseparable from the threshold cryptography in the existing Byzantine Fault Tolerant(BFT)consensus.The membership in consensus in a blockchain scenario supports dynamic changes,which effectively prevents the corruption of consensus participants.Especially in cross-chain protocols,the dynamic access to different blockchains will inevitably bring about the demand for member dynamic.Most existing threshold cryptography schemes rely on redefined key shares,leading to a static set of secret sharing participants.In this paper,we propose a general approach to coupling blockchain consensus and dynamic secret sharing.The committee performs consensus confirmation of both dynamic secret sharing and transaction proposals.Our scheme facilitates threshold cryptography membership dynamic,thus underlying support for membership dynamic of threshold cryptographybased BFT consensus schemes.We instantiate a dynamic HotStuff consensus to demonstrate the effectiveness of the scheme.After the correctness and security proof,our scheme achieves the secrecy and integrity of the threshold key shares while ensuring consensus liveness and safety.Experimental results prove that our scheme obtains dynamic membership with negligible overhead.