인증서가 · 인증서를
(digital) certificate, e-certificate (for online banking and government sites)
Example
인증서 비밀번호를 잊어버려서 다시 발급받았어요.
I forgot my certificate password, so I had it reissued.
Word parts
인 recognize+증 proof+서 document
인증 'certification' (literally 'recognize and prove') + 서 'document'.
Good to know
Korean banking and government websites use a digital certificate to confirm who you are. The old 공인 인증서 was renamed 공동 인증서 in 2020, and certificates issued inside apps are now common too. Get one issued: 인증서를 발급받다.