Security is a major concern while implementing Mobile Ad Hoc Networks (MANET) for communication in an adverse environment. The dynamism in network topology and the absence of centralized administration, MANET is susceptible to security attacks from malicious users. This paper introduces the concept of anonymity for an informant who identifies and discloses anonymously the malicious behavior of other users in the network. This paper proposes the Trust-Based Anonymous Communication Technique (TACT) to provide anonymity for an informant and liability for the malicious users who attempt to misuse the anonymity property. The TACT restrains the misuse of anonymity in such a way that any user not sending cooperation message utmost once, upon receiving warnings two times is identified and also any user sending multiple cooperation messages per warning per malicious behavior type will also be termed as malicious user. The proposed technique is designed based on “broadcast with trapdoor information” a cryptography concept to monitor the users and to report malicious users to the network anonymously. The simulation results prove the necessity of anonymity in MANET and the effectiveness of this protocol in achieving such anonymity.