Authenticity has to do with verifying your information. The quality of being authentic or of established authority for truth and correctness
Authenticity has to do with being authentic or of established authority for truth and correct labeling for something.
For example, you can authenticate your email address and get into it if you can verify it is you. Thats why you need a password to get into it. That's what Authenticity is you have to have verified information in order to have access to what you want.