One aspect relates to a communication protocol for communicating between one or more entities, such as devices, hosts or any other system capable of communicating over a network. A protocol is provided that allows communication between entities without a priori knowledge of the communication protocol. In such a protocol, for example, information describing a data structure of the communication protocol is transferred between communicating entities. Further, an authentication protocol is provided for providing bidirectional authentication between communicating entities. In one specific example, the entities include a master device and a slave device coupled by a serial link. In another specific example, the communication protocol may be used for performing unbalanced transmission between communicating entities.