@techreport{schlesinger-cfrg-act-00,
    number =    {draft-schlesinger-cfrg-act-00},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-schlesinger-cfrg-act/00/},
    author =    {Samuel Schlesinger and Jonathan Katz},
    title =     {{Anonymous Credit Tokens}},
    pagetotal = 42,
    year =      2025,
    month =     aug,
    day =       18,
    abstract =  {This document specifies Anonymous Credit Tokens (ACT), a privacy- preserving authentication protocol that enables numerical credit systems without tracking individual clients. Based on keyed- verification anonymous credentials and privately verifiable BBS-style signatures, the protocol allows issuers to grant tokens containing credits that clients can later spend anonymously with that issuer. The protocol's key features include: (1) unlinkable transactions - the issuer cannot correlate credit issuance with spending, or link multiple spends by the same client, (2) partial spending - clients can spend a portion of their credits and receive anonymous change, and (3) double-spend prevention through cryptographic nullifiers that preserve privacy while ensuring each token is used only once. Anonymous Credit Tokens are designed for modern web services requiring rate limiting, usage-based billing, or resource allocation while respecting user privacy. Example applications include rate limiting and API credits. This document is a product of the Crypto Forum Research Group (CFRG) in the IRTF.},
}