Today the 2.6 version of Mastodon has been released. It now has built-in support for “rel=me”, which allows verification. Meaning that I can show on my Mastodon profile a link to my site and can proof that both are under my control.

Rel=me is something you add to a link on your own site, to indicate that the page or site you link to also belongs to you. The page you link to needs to link back to your site and make it reciprocal. This is machine readable, and allows others to establish that different pages are under control of the same person or entity.

On my own site I use ‘rel=me’ in the about section in the right hand column. First, if you check the html source of my page, you’ll see that I say that this site (zylstra.org/blog) is my primary site, by making it the only link that has a ‘u-uid’ class (uid is unique id). It also has rel=”me”, meaning the relationship I have with the linked site, is that it is me: 

class="u-url url u-uid uid" rel="me" href='https://www.zylstra.org/blog'

Further down in that About segment you find other links, to my Mastodon and Twitter profiles. If you look at those links you will see it says:

rel=”me” href=’https://m.tzyl.nl/@ton'

saying my Mastodon profile is also me, and similarly to say that a specific Twitter profile is also me (I maintain other Twitter profiles as well but they’re not me, but my company etc.):

rel=”me” href=’https://twitter.com/ton_zylstra'

To close the loop that allows verification that that is true, both my Mastodon profile and my Twitter profile need to link back to my site in a way that machines can check. For Twitter that is easiest: it has a specific place in a user profile for a website address. Like in the image below.

In Mastodon I can add multiple URLs to my profile but there was no way for me to explicitly say in my Mastodon profile that a specific link is the one that represents my online identity. But now I can add a rel=me link in my Mastodon profile, so that both my website and my Mastodon profile link to each other in a verifiable way, proving both are under my control. As you can see in the image below it was available on a single instance already for testing purposes (the green mark signifies verification with the linked site), and now with today’s release it is available to all Mastodon instances.

So how is verification of control over different pages by the same person useful? It may be useful to show that another Twitter profile with my name is not me, because there’s no two-way link between that profile and my site. If you have multiple rel=me references it becomes harder for others to fake specific parts of your online identity. Further, it allows additional functionality like logging in on a different site using credentials from another site you control. It also makes it possible to map networks, and discovery. Site X links to profile X with rel=me on Twitter. There X follows Y, and Y’s profile says, site Y is under her control. Now I know that Site X and Site Y’s authors are somehow connected. If I’m following site X, I may find it interesting to also regularly read site Y.

As soon as my Mastodon instance has been updated to the latest version, which will likely be sometime today, I will add the rel=me in my Mastodon profile, making the link between this site and that profile verifiable.

[UPDATE] It now works on my Mastodon instance: