Usually, credentials. evidence of authority, status, rights, entitlement to privileges, or the like, usually in written form

Only those with the proper credentials are admitted.

anything that provides the basis for confidence, belief, credit, etc.

to grant credentials to, esp. educational and professional ones

She has been credentialed to teach math.

providing the basis for confidence, belief, credit, etc.

noun

accreditation , authorization , card , certificate , character , deed , diploma , docket , document , documentation , endorsement , letter of credence , letter of introduction , license , missive , papers , passport , proof , recommendation , sanction , testament , testimonial , title , token , voucher , warrant , permit , reference