countersign Synonyms

word watchword parole password countersignature validate warrant underwrite warrantee undersign subscribe subscribing witness open sesame notarise say under oath give testimony subscribes sign manual passcode initials cosign codeword key word passkey notarize subscribed signature signing endorsed corroborate confirm certify catchword autograph authorize authenticate attest assure approve endorsing endorse signed sign shibboleth seal sanction ratify promise initial