noun
In computing, an entity that issues digital certificates used in public key infrastructure.
この証明機関は信頼できるルート証明書を発行している。
This certification authority issues trusted root certificates.
認証局 is a more common term for certification authority in Japanese IT contexts, while 証明機関 is a direct translation and less frequently used.
Compound of 証明 (certification) and 機関 (organization, authority).