HTTP Public Key Pinning

Common card · No. 428512

HTTP Public Key Pinning (HPKP) is an obsolete Internet security mechanism delivered via an HTTP header which allows HTTPS websites to resist impersonation by attackers using misissued or otherwise fraudulent digital certificates. A server uses it to deliver to the client (e.g. a web browser) a set of hashes of public keys that must appear in the certificate chain of future connections to the same domain name. For example, attackers might compromise a certificate authority, and then mis-issue certificates for a web origin. To combat this risk, the HTTPS web server serves a list of “pinned” public key hashes valid for a given time; on subsequent connections, during that validity time, clients expect the server to use one or more of those public keys in its certificate chain. If it does not, an error message is shown, which cannot be (easily) bypassed by the user. The technique does not pin certificates, but public key hashes. This means that one can use the key pair to get a certificate from...

Read on Wikipedia · Image IETF HTTP Working Group (HTTPbis), Public domain