Root Causes 683: What is a Turducken certificate

In this episode about "Turducken" (post-quantum opt-out) certificates and WebPKI downgrade attacks, Jason and Tim discuss why trusting even a single classical Certificate Authority leaves the entire web vulnerable to a cryptographically relevant quantum computer. They explain how wrapping classical RSA or ECC keys inside an ML-DSA post-quantum CA signature prevents global downgrade attacks during the transition to Merkle Tree Certificates (MTCs), and walk through the 2027–2028 browser root store roadmap from Chrome and Apple.