Online anonymity refers to individuals to interact online without fully revealing their identity. To understand the motivations behind this choice in the Chinese context, we translated the Online Anonymity Questionnaire (OAQ) and assessed it with 1,405 college students in Guangxi, China, followed by a retest with 245 participants a month later. The study evaluated the reliability and validity of the Chinese version of the OAQ, assessing internal consistency, test-retest reliability, confirmatory factor analysis, and measurement invariance. The questionnaire, featuring two dimensions—anonymous self-expression and anonymous toxicity—demonstrated good internal reliability and test-retest reliability for both subscales. Confirmatory factor analysis showed the two-factor model was a good fit (CFI = 0.98, TLI = 0.97, RMSEA = 0.05), and partial scalar invariance was confirmed. These findings validate the Chinese version of the OAQ for studying online anonymity motivations among Chinese college students.

Conventional blockchains can provide data availability and integrity only. Tons of applications additionally need confidentiality with flexible access control such that data providers can decide how their data are shared through blockchains. This paper aims at enhancing Byzantine Fault Tolerance (BFT)-based permissioned blockchains with controllable access control. To this goal, we extend the concept of Proxy Re-Encryption (PRE) to a new variant called Controllable Threshold PRE (CT-PRE). The traditional PRE enables a proxy, using a re-encryption key, to convert a ciphertext meant for delegator A into another ciphertext meant for delegatee B, all without exposing the original message. CT-PRE extends PRE into the setting with multiple proxies (corresponding to blockchain servers and avoiding a single point of failure) and enables the delegator to fully take control of its ciphertext. We formally define CT-PRE and construct a provably secure CTPRE scheme. We further extend the CTPRE scheme to a verifiable one VCTPRE. We implement the Verifiable CT-PRE scheme with stronger security, integrate it in our BFT-based blockchain system, and deploy our system in a WAN on Amazon EC2 with 22 nodes across four continents. We show that our system is highly efficient, achieving a throughput of 5.15 ktx/sec (for access control operations) and 10.83 ktx/sec (for write operations, only slightly slower than our BFT write operations), respectively.

A key management service (KMS) is vital to modern mission-critical systems. At the core of KMS are the key generation process and the key refresh process. In this paper, we design and implement a purely asynchronous system for completely distributed KMS supporting traditional applications such as threshold cryptosystems and multiparty computation (MPC) as well as emerging blockchains and Web3 applications. In this system, we have built a number of new asynchronous distributed key generation (ADKG) protocols and their corresponding asynchronous distributed key refresh (ADKR) protocols. We have demonstrated that our ADKG and ADKR protocols in the standard model outperform existing ones of the same kind, while our protocols in the random oracle model (ROM) are more efficient than other protocols with small and medium-sized networks.