OTFcreds: Activity 2.2 Research scientific literature

[jbonisteel]

We will review cryptographic literature on the topic, estimate the performance of each selected cryptographic scheme, and estimate the difficulty in maintaining such a library in the years to come.

• A non-exhaustive list of possible directions that we started investigating already comprehends:
• Generic anonymous credential schemes that support zero-knowledge proofs on the top of them for the selective disclosure of attributes, providing anonymity [CB01];
• Blind signatures [C82, IETF] and Verifiable Oblivious Pseudorandom Functions [JKK14, IETF]: two lightweight anonymous credential systems already under standardization from IETF (and thus fully specified and with deployments) that provide little flexibility and no revocation yet;
• Algebraic MACs [CMZ14], a secret-key anonymous credential system that is flexible and supports selective disclosure of attributes, currently deployed within Signal for their group messaging system.

This activity will mainly be carried out by the cryptographer. Some members of the OONI team (CTO and research engineer) will also study the relevant literature to better understand the constraints of the technology (backend engineer, mobile engineer) to answer any questions about the components they maintain.

Output: the findings from the literature review are detailed in a document.