The whitepaper introducing the Basic Attention Token (BAT) [1] was released mid 2017 and, since then, BAT has been used by millions of users, advertisers, and publishers, each using and earning BAT through the Brave Browser (Figure 1) [2]. It has been a long ride since 2017 and we’re very proud that BAT is acknowledged as one of the most successful use cases for decentralized ledgers and utility tokens.
The BAT token powers the BAT-based advertising ecosystem. The main goal of the BAT-based ad ecosystem is to provide the choice for users to value their attention, while keeping full control over their data and personal privacy. The main tenets of the BAT-based advertising ecosystem are to provide privacy by default, to restore control to users over their data, and to provide a decentralized marketplace where Brave Browser users are incentivized to watch ads and to contribute to creators. Through these principles, Brave’s vision is to fix the current online advertising industry [1], and get rid of widespread fraud schemes [3] [3.1], [4], market fragmentation [5] [6] and privacy issues [7] [8].
In line with these goals, Brave’s research team has been working on a decentralized and privacy-by-design protocol that further improves upon the current BAT-based ad ecosystem. In this first post in a series of blog posts, we present THEMIS: a novel privacy-by-design ad platform that requires zero trust from both users and advertisers alike. THEMIS provides auditability to all participants, rewards users for interacting with ads, and allows advertisers to verify the performance and billing reports of their ad campaigns. In this blog series, we describe the THEMIS protocol and its building blocks. In the next post, we will present a preliminary scalability evaluation of THEMIS in a deployment environment.
Figure 1. Example of an ad notification delivered through the Browser for Brave Ads users.
Digital advertising is the most popular way of funding websites. However, web advertising has fundamental flaws such as market fragmentation, rampant fraud, and unprecedented invasion of privacy. Further, web users are increasingly opting out of web advertising, costing publishers millions of dollars in ad revenues every year. A growing number of users (47% of internet users globally, as of today [13]) use ad-blockers.
Academia and industry have responded by designing new monetization systems. These systems generally emphasize properties such as user choice, privacy protection, fraud prevention, and performance improvements. Privad [11], and Adnostic [12] are examples of academic projects that focus on privacy-friendly advertising. Despite the contributions of these systems, they have significant shortcomings that have limited their adoption. These systems either (i) do not scale, (ii) require the user to trust central authorities within the system to process ad transactions, or (iii) do not allow advertisers to accurately gauge campaign performance.
To make matters worse, current advertising systems lack proper auditability: The ad network exclusively determines how much advertisers will be charged, as well as the revenue share that the publishers may get. Malicious ad networks can overcharge advertisers or underpay publishers. Another issue is non-repudiation, as ad networks do not generally prove that the claimed ad views/clicks occurred in reality.
