https://nakedsecurity.sophos.com/2015/02/16/memex-darpas-search-engine-for-the-dark-web/
Memex – DARPA’s search engine for the Dark Web
2015
Enter Memex, brainchild of the boffins at DARPA, the US government agency that built the internet (then ARPANET).
DARPA describes Memex as a set of search tools that are better suited to government (presumably law enforcement and intelligence) use than commercial search engines.
Whereas Google and Bing are designed to be good-enough systems that work for everyone, Memex will end up powering domain-specific searches that are the very best solution for specific narrow interests (such as certain types of crime.)
Today's web searches use a centralized, one-size-fits-all approach that searches the internet with the same set of tools for all queries. While that model has been wildly successful commercially, it does not work well for many government use cases.
The goal is for users to … quickly and thoroughly organize subsets of information based on individual interests … and to improve the ability of military, government and commercial enterprises to find and organize mission-critical publically [sic] available information on the internet.
Although Memex will eventually have a very broad range of applications, the project’s initial focus is on tackling human trafficking and slavery.
According to DARPA, human trafficking has a significant Dark Web presence in the form of forums, advertisements, job postings and hidden services (anonymous sites available via Tor).