The potential of by selection sharing encrypted knowledge with totally different users via public cloud storage might greatly ease security issues over unintended knowledge leaks within the cloud. A key challenge to coming up with such coding schemes lies within the economical management of coding keys. the specified flexibility of sharing any cluster of chosen documents with any cluster of users demands totally different coding keys to be used for various documents. However, this additionally implies the requirement of firmly distributing to users an outsized variety of keys for each coding and search, and people users can got to firmly store the received keys, associate degreed submit an equally sizable amount of keyword trapdoors to the cloud so as to perform search over the shared data. The tacit want for secure communication, storage, and complexness clearly renders the approach impractical. during this paper, we have a tendency to address this sensible downside, that is essentially neglected within the literature, by proposing the novel conception of key combination searchable coding (KASE) and instantiating the conception through a concrete KASE theme, during which an information owner solely must distribute one key to a user for sharing an outsized variety of documents, and therefore the user solely must submit one trapdoor to the cloud for querying the shared documents. the protection analysis and performance analysis each ensure that our planned schemes square measure incontrovertibly secure and much economical.