Authentication and non-repudiation are two different sorts of concepts.
Authentication is a technical concept: e.g., it can be solved through cryptography.
Non-repudiation is a legal concept: e.g., it can only be solved through legal and social processes (possibly aided by technology).
Some people have been taught that non-repudiation can be provided through crypto-mathematics alone. However, that is not correct.However, that is not correct.