Root Causes 688: eMudhra exits the WebPKI after key compromise

In this episode about the key compromise at the public certificate authority eMudhra and its exit from the WebPKI, Jason and Tim discuss how a researcher found intermediate CA keys with only one byte of entropy and what eMudhra's incident report says went wrong. They walk through the move of keys between hardware security modules (HSMs), the scripting error that replaced the original keys outside the HSMs' safeguards, and the tighter key generation rules Tim expects from the CA/Browser Forum, and why, unlike with Heartbleed, no subscriber can know whether an attack already took place.

Clarification: eMudhra's incident report lists 16 affected intermediate CAs. Eight of them, the elliptic curve (ECDSA P-384) keys, had only one byte of entropy, not all 16 as said in the episode.