  Recently, Chang et al (Quantum Inf Process,14,3515,2015) proposed a
controlled bidirectional quantum direct communication protocol using Bell
states. In this work, the significance of Bell states, which are being used as
initial states in Chang et al. protocol, is elucidated. The possibility of
preparing initial state based on the secret message of the communicants is
explored. In doing so,the controller-independent bidirectional quantum direct
communication protocol has evolved naturally. It is shown that any communicant
cannot read the secret message without knowing the initial states generated by
the other communicant. Further,intercept and resend attack and information
leakage can be avoided. The proposed protocol is like a conversion between two
persons without the help of any third person with high-level security.
