Definition
Plain language
The trusted issuer that hands out the digital ID cards other machines will accept.
As stated in the literature
The signing authority in a PKI or SSH CA setup; it issues certificates binding keys to identities and scopes, so compromise of its signing flow grants broad access.
Also called: CA, SSH certificate authority
Why it matters: It replaces thousands of scattered credentials with one trust decision, which is far cleaner to manage and far more catastrophic if someone gets to do the signing.
For example, instead of copying a password onto every server, a company has one signing service issue short-lived certificates saying "this key belongs to Alice and may log into the web servers," and every server accepts them because it trusts that signer.
Heard on the show
“They set up an agent running an SSH certificate authority, and asked it to sign a certificate for a new engineer.”Episode 269 — How a Forged Transcript Got Model Weights Past a Safety Monitor