I don't know if you're still checking this thread but you can search for "Key Transparency" and "CONIKS" that are two projects that store key data in blockchain

I don't know if you're still checking this thread but you can search for "Key Transparency" and "CONIKS" that are two projects that store key data in blockchain-like structures. See also comparison: https://blog.okturtles.org/2017/02/coniks-vs-key-transparency-vs-certificate-transparency-vs-blockchains/ https://blog.okturtles.org/2017/02/coniks-vs-key-transparenc...