Internet Engineering Task Force (IETF) C. Evans Request for Comments: 7469 C. Palmer Category: Standards Track R. Sleevi ISSN: 2070-1721 Google, Inc. April 2015 Public Key Pinning Extension for HTTP Abstract This document defines a new HTTP header that allows web host operators to instruct user agents to remember ("pin") the hosts' cryptographic identities over a period of time. During that time,