  In this paper, we consider a more general four-terminal memoryless
relay-eavesdropper channel with state information (REC-SI) and derive an
achievable perfect secrecy rate for it. We suppose that the state information
is non-causally available at the transmitter and relay only. The transmitter
wishes to establish a secure communication with the legitimate receiver by the
help of a relay where a confidential message will be kept secret from a passive
eavesdropper. We consider active cooperation between the relay and transmitter.
The relay helps the transmitter by relaying the message using
decode-and-forward (DF) scheme. The proposed model is a generalization of some
existing models and the derived achievable perfect secrecy rate is compared to
the special cases. The results are also validated numerically for the additive
white Gaussian noise (AWGN) channel.
