Among existent technology, a few applications think about the existence of tiny devices that may exchange data and type communication networks. In an exceedingly good portion of such applications, the confidentiality and integrity of the communicated messages are of specific interest. During this paper, the authors tend to propose 2 novel techniques for authenticating short encrypted messages that square measure directed to meet the wants of mobile and pervasive applications. By taking advantage of the actual fact that the message to be echt must even be encrypted, they tend to propose demonstrably secure authentication codes that square measure additional economical than any message authentication code within the paper.