Accountable Anonymous Credentials

Anonymity refers to withholding the identification information associated with an interaction. In the cyberworld, anonymous authentication is an important tool for protecting privacy. However, users may misbehave under the cover of anonymity, thus, accountability is crucial in any practical privacy-preserving authentication. Balancing anonymity and accountability has always been a challenging research problem in privacy protection. Accountable anonymous credentials are the cryptographic schemes designed to address this challenge. Users are allowed to anonymously prove their possession of valid credentials to protect user privacy. If they misbehave, they will be de-anonymized or blacklisted. In other words, it is technically possible for a system to achieve both anonymity and accountability simultaneously. In this chapter, we review the concept of anonymous credentials and discuss various accountability mechanisms. We discuss how the recent development of blockchain and quantum computers have influenced the recent research advances in this area. Finally, we also discuss how anonymous credentials are applied in real-world applications in cryptocurrencies.