https://noncombatant.org/2015/05/01/about-http-public-key-pinning/
https://scotthelme.co.uk/hpkp-toolset/
https://report-uri.io/home/tools
http://blog.rlove.org/2015/01/public-key-pinning-hpkp.html
http://news.netcraft.com/archives/2016/03/30/http-public-key-pinning-youre-doing-it-wrong.html
What Is Pinning, And What Does It Solve?
HPKP is an attempt to solve 1 of the big problems in the Web PKI: the fact that essentially any certification authority (CA) or intermediate issuer can issue end-entity (EE, or “leaf”) certificates for essentially any web site. For example, even though the certificate for mail.google.com is issued by “Google Internet Authority G2”, which in turn is issued by the root CA “GeoTrust Global CA”,an obscure Dutch CA can also try to issue certificates for mail.google.com. So, we’d really like some way to stop clients from having to trust such misissued certificates.
