Privacy-preserving authentication is an emerging field focused on enhancing user privacy in digital identity management systems. The current authentication systems often expose user identities, which raises concerns about privacy. This Dagstuhl Seminar addresses key challenges in the development and deployment of privacy-preserving authentication techniques, particularly anonymous credentials and blind signatures, which allow users to prove possession of credentials without revealing their identities. The seminar explores several critical issues, including the integration of post-quantum security, efficient revocation mechanisms, and the standardization of privacy-enhancing technologies like anonymous credentials, anonymous tokens, blind signatures, etc.