Secure yet lightweight protocol for communication over the Internet is a pertinent problem for constrained environments in the context of Internet of Things (IoT) / Machine to Machine (M2M) applications. This paper extends the initial approaches published in ,  and presents a novel cross-layer lightweight implementation to establish a secure channel. It distributes the responsibility of communication over secure channel in between the application and transport layers. Secure session establishment is performed using a payload embedded challenge response scheme over the Constrained Application Protocol (CoAP) .
Record encryption mechanism of Datagram Transport Layer Security (DTLS)  with Pre-Shared Key (PSK)  is used for encrypted exchange of application layer data. The secure session credentials derived from the application layer is used for encrypted exchange over the transport layer. The solution is designed in such a way that it can easily be integrated with an existing system deploying CoAP over DTLS-PSK. The proposed method is robust under different security attacks like replay attack, DoS and chosen cipher text. The improved performance of the proposed solution is established with comparative results and analysis.