Wireless sensor networks has been growing rapidly over the past few decades. Due to their flexibility, wireless sensor networks have been in practice in many areas. Unlike other network architectures, Mobile Ad hoc networks (MANETs) have no central architecture; every node is free to work both as a transmitter and receiver and it depends on neighboring nodes to send relay messages. Due to their advantages, MANETs are used in many different applications like health care and military. However the wide distribution of MANETs makes it vulnerable to malicious attacks. Hence it is necessary to design a secure system for MANETs. In this report, we implement a secure system named Enhanced Adaptive Acknowledgement especially for MANETs. To ensure higher security and reduce the network overhead and delay, we use a different approach called hybrid cryptography in our proposed scheme. Enhanced Adaptive Acknowledgment detects higher malicious attackers without greatly disturbing the network performances. In the simulation we compare the differences within the Enhanced Adaptive Acknowledgment (EAACK) before and after introducing the Hybrid cryptography approach.