Which of the following is the most secure authentication scheme and uses a public key cryptography and digital certificate to authenticate a user?

A.
Form-based authentication

B.
Basic authentication

C.
Digest authentication

D.
Certificate-based authentication

Explanation:
Certificate-based authentication is the most secure authentication scheme. A certificate-based authentication scheme is a scheme that uses a public key cryptography and digital certificate to authenticate a user. A digital certificate is an electronic document that includes identification information, public key, and the digital signature of a certification authority based on that certification authority’s private key. When a user connects to the server, he presents his digital certificate containing the public key and the signature of the certification authority. The server verifies the validity of the signature and whether the certificate has been provided by a trusted certificate authority or not. The server then authenticates the user by using public key cryptography to prove that the user truly holds the private key associated with the certificate. Answer option B is incorrect. Basic authentication is a simple method of authentication that provides minimum security. It should be used only when security is not critical because basic authentication requests are not encrypted.
Answer option A is incorrect. Form-based authentication Form-based authentication allows users to create their own custom forms. It requires session tracking for the authentication, so that the container may use the login form. It is not a secure authentication scheme. Answer option C is incorrect. Digest authentication is a secure authentication method in which passwords are sent across a network as a hash value rather than as clear text. It is a more secure authentication method as compared to Basic authentication. Digest authentication works across proxy servers and firewalls.