Shameless plug (but I hope that's okay, again): IRMA Authentication is an open-source app [1] and protocol that offers privacy-friendly attribute based authentication and signing using Camenisch and Lysyanskaya's Idemix [2].<p>It's currently heavily focused towards The Netherlands, where citizens can obtain attributes such as name, home address and age. These attributes can then be selectively disclosed directly to a service provider, without the identity provider being able to see the transaction [3]. Multiple disclosures are also unlinkable as long as the attributes themselves are not identifying.<p>The fact that the identity provider is not at all involved with the transaction is an enormous privacy win compared to OpenID Connect, especially in the case of centralizing providers such as Apple – and less so in for example the domain of education single sign-on.<p>It's not currently using the verifiable claims data model, but it would very much fit it. It also doesn't use a 'blockchain', simply because it's not necessary to do so, and makes it all a lot less complicated.<p>[1] <a href="https://github.com/privacybydesign" rel="nofollow">https://github.com/privacybydesign</a><p>[2] <a href="https://privacybydesign.foundation/publications/" rel="nofollow">https://privacybydesign.foundation/publications/</a><p>[3] <a href="https://privacybydesign.foundation/meeting-slides/slides-8-3-19/ringers-8-maart-2019.pdf#page=2&zoom=auto,-68,540" rel="nofollow">https://privacybydesign.foundation/meeting-slides/slides-8-3...</a>