An authentication method of a prover by a verifier includes: performing at least once, an enrollment process by an enrollment center computer; and subsequent to performing the enrollment process, performing an on demand authentication process including: receiving at a verifier computer from the prover, a prover authentication request sent from the prover computer device which includes the prover identity and a preferred ZKP protocol identifier; looking up a prover's public key in the database via the identity; the verifier sending a selected ZKP protocol identifier to the prover computer device; commencing a round of authentication by receiving a commitment generated according to the selected ZKP protocol; and repeating the step of commencing a round of authentication until the verifier computer accepts or rejects the prover's identity. A zkMFA method of authentication and an authentication system for authenticating a prover by a verifier are also described.