A Mobile Ad-Hoc Network is a collection of wireless devices (say nodes) which are connected without a predetermined infrastructure such as access points or independent base stations. Due to infrastructure-less architecture, there is a necessity of integrity, confidentiality and security in the network. These networks are interlinked with all the devices in particular network in possible multihop paths. In the accordance with the characteristics of MANET, nodes are easily compromised by the adversaries. The existing trust model can make the decision for identifying the malicious nodes. However, this model did not have any misbehavior attack detection strategy. In general, the detection of misbehaving attack is complex due to the mobility of node. In order to overcome these issues, In this paper an innovative scheme is proposed to monitor and detect the malicious nodes without compromising the network performances. The major contribution is to alleviate the Watchdog (IDS for MANET) issues such as limited transmission power, packet dropping, receiver collision and false misbehavior reports generation. The proposed approach is an acknowledgement based, in which each acknowledgement packet is digitally signed with an Next Generation Cryptography (NGC) algorithm for authenticating the acknowledgement packets. Simulation results demonstrate that the proposed scheme offer more security and improve the network performances than earlier IDS approaches. The proposed system improves the packet delivery ratio and also minimizes the routing overhead even in the presence of malicious nodes in the network.Keywords: MANET (Mobile Ad hoc NETwork), multi hop network, ECKCDSA (Elliptic curve Korean Certificate Based Digital Signature Algorithm), SHA (Secure Hash Algorithm).