authenticate

v. t. [ imp. & p. p. Authenticated p. pr. & vb. n. Authenticating (&unr_;). ] [ Cf. LL. authenticare. ] 1. To render authentic; to give authority to, by the proof, attestation, or formalities required by law, or sufficient to entitle to credit. [ 1913 Webster ]

The king serves only as a notary to authenticate the choice of judges. Burke. [ 1913 Webster ]

2. To prove authentic; to determine as real and true; as, to authenticate a portrait. Walpole. [ 1913 Webster ]