JMT_V2_N2_RP2 S.B. Ninu S. Behin Sam Journal on Mobile Applications and Technologies 2394-0239 2 2 19 26 Hybrid Cryptosystems, Advanced Encryption Standard Algorithm, Hybrid Enhanced Adaptive AcKnowledgment (HEAACK), Mobile Adhoc Network (MANET) Mobile Adhoc Network (MANET) is one of the most important and unique applications. When compared to traditional network architecture, MANET does not require a fixed network infrastructure instead dynamic and distributed in nature; every single node act as both a transmitter and a receiver. In same communication range, the nodes communicate directly with each other. For outer range, they rely on their trust based neighbors to relay messages. In this case, it is crucial to develop efficient intrusion-detection mechanisms to protect MANET from attacks. In this paper, the authors propose and implement a new intrusion detection system named Hybrid Enhanced Adaptive Acknowledgment (HEAACK) specially designed for MANETs. They extend their work with the introduction of Hybrid Crypto systems to prevent the attacker from forging acknowledgment packets and reduce the network overhead which is caused by Digital Signature. In order to obtain the optimal AESs in MANETs, the authors have implemented DSA, RSA and AES schemes in the simulation. Eventually, they arose to a conclusion that the AES scheme is more suitable to be implemented in the MANETs. Simulation results show that the proposed Hybrid cryptosystem method is a more desirable scheme under MANETs. May - July 2015 Copyright © 2015 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=4872