1. In infosec, authenticity is about making sure that the message received is the same as the message that was sent. In law, authenticity is about validating that evidence has been gathered correctly by a reliable source and hasn't been tampered with. Contrast: The terms integrity and authenticity are widely used to mean the same thing. In other situations, they have subtly different meanings (especially law). The term integrity generally describes defending against malicious change of a message once it has been sent, whereas authenticity implies some sort of validation of the sender of the message to protect against forgeries. Contrast: The terms authentication and authenticity are widely used to mean the same thing. The subtle difference is that authentication is about someone proving who they say they are, whereas authenticity is about proving that message was sent by a certain person. From Hacking-Lexicon