Design and Implementation of an Anonymous and Secure Online Evaluation Protocol

Course evaluations have become a common practice in most academic environments. To enhance participation, evaluations should be private and ensure a fair result. Related privacy-preserving method and technologies (e.g., anonymous credentials, Privacy Attribute-Based Credentials, and domain signatures) fail to address, at least in an obvious way, the minimal security and practicality requirements. In this paper, we propose, evaluate, and implement an efficient, anonymous evaluation protocol for academic environments. The protocol borrows ideas from well-known and efficient cryptographic approaches for anonymously submitting ballots in Internet elections for issuing one-time credentials and for anonymously broadcasting information. The proposed protocol extends the above approaches in order to provably satisfy properties such as the eligibility, privacy, fairness and verifiability of the evaluation system. Compared to the state of the art, our approach is less complex and more effective, while security properties of the proposed protocol are verified using the ProVerif cryptographic protocol verifier. A web-based implementation of the protocol has been developed and compared to other approaches and systems.