Anonymous Tokens with Hidden Metadata Bit

This lecture introduces the concept of anonymous tokens with hidden metadata bit, focusing on the challenges of establishing trust between clients and servers in the context of DDoS attacks and click fraud. The presentation covers the use of cryptographic primitives, such as OPRFs, in token generation, the prevention of double spending, and the implementation of hidden metadata bits to address security concerns. The lecture also discusses the ATHM protocol, which involves both clients and servers in token computation, and the implications of algebraic MACs in enhancing security. Additionally, the presentation explores the UNLINK and COMUF security aspects, along with practical implementation results comparing different token systems.