A technique controls access to a protected resource residing on a protected resource server. The technique involves conveying, in response to a user request to access the protected resource residing on the protected resource server, a challenge from a resource accessing device to an access control device. The technique further involves transmitting an answer to the challenge from the access control device to the resource accessing device. The technique further involves completing an authentication operation based on the answer to the challenge. The resource accessing device obtains electronic access to the protected resource residing on the protected resource server when the authentication operation results in successful authentication. The resource accessing device does not obtain electronic access to the protected resource residing on the protected resource server when the authentication operation results in unsuccessful authentication.