Brave/BAT Ads and THEMIS

Request For Comments and Code (RFC&C) Event

The Brave research team has been working on the THEMIS protocol [1] [2] [3] to progressively decentralize the Brave/BAT Ads [4] infrastructure, while providing users and advertisers the ability to verify that the protocol is running correctly. Today, we announce an event where the community has the opportunity to participate in the design and development of the next generation of Brave Ads and Rewards.

Brave Browser and Basic Attention Token(BAT) have seen rapid growth since we launched the browser and token in 2016 and 2017 respectively. Brave has over 24 million monthly active users and over 7 million daily active users, while BAT is one of the most used tokens with close to 12M wallets, 4.3M monthly transacting BAT users, 1 million verified publishers, and more than 400 advertisers.

The current protocol has been able to distribute millions of opt-in ads to our users, while preserving the privacy of the users and rewarding them for their attention to ads. Currently, in order to serve privacy-preserving ads at scale, the infrastructure that distributes and keeps the state of the user rewards is implemented in each Brave browser instance, and anonymously in Brave servers. Although the privacy of the users is protected by design, users and advertisers need to trust that the rewards being paid are correctly computed by Brave.

In order to remove the need for trust, the Brave Research team is designing and building THEMISv2. THEMISv2 allows users to request updates and validate their rewards state in a private and unlinkable way. Users can also calculate the rewards they should receive, and submit proofs of correctness to Brave and other participants in the protocol. In addition to increasing “trustlessness”, THEMISv2 is a step forward in decentralizing the current infrastructure, as it offloads the reward calculation to the users while allowing third parties to independently verify the results of the protocol. The current design of THEMISv2 relies on cryptographic accumulators [5], ZK-S*ARKs, L2 verification and other cryptographic tools.

RFC&C Event

The Request For Comments and Code (RFC&C) community event is a 2 month event where the Brave Research team, companies and projects in the cryptography space, and researchers will come together to engage in technical discussions and collaborations to push THEMISv2 forward towards production. The RFC&C is a great opportunity for crypto projects to actively shape the future of the BAT ecosystem. As we go through the various phases, we will regularly share updates with the community and hold sessions to answer the questions that the participating teams might have.

The RFC&C consists of three distinct phases:

Phase 1
First, the Brave Research team will organize public sessions where the THEMISv2 components are presented and  discussed. The  goal  of  the  first  phase (from the 8th January to the beginning of February) is  to  introduce  THEMISv2  to  the community, and make sure the teams who want to participate in the RFC&C event are prepared to contribute. 

Phase 2
In the second phase (from the beginning of February to the of 15th March), the participants will propose modification to the THEMISv2 protocol. We will accept and review any suggested modification to the protocol regardless of how much they change the current design and implementation of the protocol, as described in this document (e.g., replacing the SNARKs-based verification  on-chain  by  a  scalable  L1  option).   However,  we  expect  the  goals and  requirements  described  in  this  document  to  hold  true  even with  proposed  modifications.   The  Brave  Research  team  will  run  1-1  sessions  with participants, where we can discuss protocol details and open the floor to any  questions.   In  addition,  there  will  be  a  public  Discord  channel  to  answer questions the participants may have during this phase.

Phase 3
The third phase (from the 15th March to the end of March) of the event consists of the Brave Research team reviewing the submissions and reaching out for potential partnerships. The reviewing process will consider all comments and technical suggestions. The submissions may range from proposing changes to our initial protocol, to a completely new design and MVP (e.g. BAT transacted on a different L1 blockchain, etc).

Over the next few weeks, we will release a technical report describing the current protocol design, threat model and requirements. In addition, we will share the detailed timeline and logistics for the event. If you are excited about joining us for the RFC&C event and contributing, or if you have any questions, feel free to join the RFC&C technical Discord channel.



  1. THEMIS: Decentralized and Trustless Ad Platform with Reporting Integrity
  2. THEMIS: Towards a Decentralized Ad Platform with Reporting Integrity (Part 1)
  3. THEMIS: Progressive Decentralization with Smart Contracts and Sidechains (Part 2)
  4. Brave Ads | Advertise with Brave
  5. Revisiting Cryptographic Accumulators, Additional Properties and Relations to other Primitives

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