Collocations for authenticity - noun

cast doubt on, dispute, doubt, question
Some have cast doubt on the authenticity of the official version of events.

ascertain, check, test
certify, confirm, establish, prove, validate, verify

a certificate of authenticity
Despite its certificate of authenticity, the painting was a fake.

a debate over the authenticity of sth
There has been some debate over the authenticity of his will.

of doubtful authenticity (esp. BrE), of dubious authenticity (esp. AmE), of questionable authenticity (esp. AmE)
a document of doubtful authenticity