A company is deploying a file-sharing protocol across a network and needs to select a protocol for authenticating clients, Management requests that the service be configured in the most secure way possible. The protocol must also be capable of mutual authentication, and support SSO and smart card logons. Which of the following would BEST accomplish this task?

• Store credentials in LDAP
• Use NTLM authentication
• Implement Kerberos
• Use MSCHAP authentication