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certificate authority (CA)
A trusted party allowed to vouch for identities by signing digital certificates.
In public-key security, a certificate binds a name to a public key, and it is only trustworthy if signed by an authority you already trust — a certificate authority. Certificates carry a flag marking whether the holder is itself allowed to act as a CA and sign others; requiring that flag on every issuer prevents a leaf certificate from illegitimately signing new ones. CAs are the anchors of the trust system.
See also
- certificate chainAn ordered sequence of certificates linking the one you're checking up to a root you already trust.
- chain verificationChecking that a certificate is legitimately signed all the way up to an issuer you trust.