We recently ran a survey on the usability of Tor and onion services [0]. I had a closer look at how our respondents perceive the prop224 domain format and wanted to share some early insights. The original survey question was:

The Tor Project is currently working on the next generation of onion services. The new onion domain format will consist of 52 characters, for example: a1uik0w1gmfq3i5ievxdm9ceu27e88g6o7pe0rffdw9jmntwkdsd.onion Do you expect this to change your browsing habits?

591 users answered this question. 95 (16%) selected that prop224 domains will change their habits while the remaining 496 (84%) selected that their habits won't be affected.

Respondents who believe that their habits will change (16%) gave the following reasons:

- Several users memorise a number of onion domains -- most prominently Facebook's onion domain and self-hosted domains. They write that memorising domains will no longer be possible, and they will look into bookmarking tools. Several users voiced concern about the confidentiality of their bookmarks, so they are looking into ways to encrypt them.

- Similarly but less commonly, users voice concerns that communicating, typing, and writing down prop224 domains will no longer be feasible.

- A small number of users write that it will be harder to recognise onion domains. Alarmingly, one user mentioned that the lack of a discernible prefix will make it hard to recognise genuine domains, suggesting that they rely on an onion domain's easy-to-spoof vanity prefix.

- A user suggested to add spaces to prop224 domains to "make the address more visually appealing."

Respondents who believe that their habits will *not* change (84%) gave the following reasons:

- The majority of this crowd never bothered to memorise onion domains and uses bookmarks. A bunch of users store domains in text files and an even smaller bunch uses search engines to rediscover domains. In general, most people in this category treat onion domains as an opaque identifier.

- Some users write that the additional inconvenience is likely worth the extra security and anonymity.

- Some users mention Reddit as their primary way of discovering onion domains.

Judging by the above, I believe that the new domain format is among the minor usability issues surrounding onion services. In fact, an easy-to-remember domain format ranks last among the six criteria whose importance we asked users about. On a five-point Likert scale ranging from "not at all important" to "very important," we got the following results:

- 77% think that quality of content is at least somewhat important. - 70% think that a search engine (like Google) for onion services is at least somewhat important. - 66% think that diversity of content is at least somewhat important. - 62% think that page load time is at least somewhat important. - 43% think that having an onion service version of popular services such as Facebook is at least somewhat important. - 26% think that an easy-to-remember domain format is at least somewhat important.

However, our survey data is likely biased towards a particularly young and educated crowd that's presumably less bothered by technological hurdles, which may be why they can afford to care more about content.

[0] https://blog.torproject.org/take-part-study-help-improve-onion-services

Cheers, Philipp