Provided are a method and a system for mutual authentication between mobile and host devices. The mobile device stores a first secret key and is connected to the host device. The method includes generating a second secret key using the first secret key and first data that is received from the host device and is encrypted using a predetermined method. The method further includes transmitting second data that is encrypted using a predetermined method, to the host device to induce generation of a media key; performing an operation on the second secret key and transmitting a generated operation value to the host device; and performing mutual authentication between the mobile device and the host device.