  Onion services are anonymous network services that are exposed over the Tor
network. In contrast to conventional Internet services, onion services are
private, generally not indexed by search engines, and use self-certifying
domain names that are long and difficult for humans to read. In this paper, we
study how people perceive, understand, and use onion services based on data
from 17 semi-structured interviews and an online survey of 517 users. We find
that users have an incomplete mental model of onion services, use these
services for anonymity and have varying trust in onion services in general.
Users also have difficulty discovering and tracking onion sites and
authenticating them. Finally, users want technical improvements to onion
services and better information on how to use them. Our findings suggest
various improvements for the security and usability of Tor onion services,
including ways to automatically detect phishing of onion services, more clear
security indicators, and ways to manage onion domain names that are difficult
to remember.
