Distributed verification or proof that an account on one site is under the control of the same person as another site has been enabled by several sites or plugins.
- Jeremy Keith has built Huffduffer to follow rel="me" links to show your connected social accounts without you having to enter them individually.
- Kevin Marks built a browser plugin which matches rel-me links on sites and provides either green checkmarks or red Xs to indicate a bi-directional link between the two.
Various social network silos (e.g. Flattr, Google) has or has had verification of third party content on their sites.
Flattr uses internally mapped URL:s to known proprietary identities and then used proprietary OAuth API:s of other services, like Twitter and GitHub, to let user verify multiple identities per platform.
Google's "Authorship in web-search" feature used rel-author and similar to establish authorship of a web page and then tried connecting that to a Google+ profile, either directly or indirectly by following rel-me links to and from the authors profile and the Google+ profile. Google then presented a profile of that user in connection to the page in their search result.
Twitter offers a subset of users the option of a blue "verified" checkmark icon on their name/profile, intended to "establish authenticity of identities of key individuals and brands on Twitter."
Twitter has come under increasing fire in 2016/2017 for having a relatively opaque process by which they verify users or not. Their verification is only available to certain (unknown) classes of users, despite their stated terms, which causes an imbalance of perceived power and influence on the platform.
On 2017-11-09 Twitter itself acknowledged this problem:
Verification was meant to authenticate identity & voice but it is interpreted as an endorsement or an indicator of importance. We recognize that we have created this confusion and need to resolve it. We have paused all general verifications while we work and will report back soon
Strava may designate "notable public figures" as "Verified", however "It is not currently possible to request or purchase a verified badge."
Strava also has "clubs" which can apparently sometimes get verified as well, by filling out a form:
What's another way to show Plurk users my account is authentic?
Linking to your Plurk profile from an official website is the easiest way to confirm your identity to your fans.
Authorship + Rel-Me
First determine the authorship of a web page. If the author profile is on the same site (same host name) as the web page, and thus can be expected to not have been spoofed, then check for a bi-directional rel-me link between that author profile and the identity profile to verify it as.
To enable verification of more complex rel-me identity links one would need to compile an entire identity graph, the identity's own subset of the full social graph, and traverse the identity graph from the author profile, to the target and then back and ensure that the full chain of links exists and are valid. This would require something like identengine or RelSpider .