Now-a-days the bases of cryptographic systems are being challenged too frequently as the system computation tradition is fluxing its trend from small scale computation towards giant intact calculations. It demands of highly complex cryptographic nonlinear dynamic system. Chaos and cryptography have some common features, the most important being sensitivity to initial conditions, parameters' and variables' changes. Here we implemented chaotic behavior in signcryption to provide higher security when communicating a sensitive data over insecure network.