Authenticity

Authenticity is the degree to which the identity of a subject or resource can be proven to be the one it claims to be. It is a quality attribute and, per ISO/IEC 25010, a sub-characteristic of security, alongside confidentiality, integrity, non-repudiation, and accountability.

A system establishes authenticity through mechanisms such as authentication credentials, digital signatures, and certificates, each of which ties a claimed identity to evidence that only the genuine subject could plausibly produce. Without it, a system has no reliable basis for trusting who or what it is communicating with, which undermines every other security control built on top of that trust.