In the past few years, secure transmission of data along with efficiency is a serious issue for Wireless Sensor Networks (WSNs).Clustering is a powerful and convenient way to enhance performance of the WSNs system. In this paper, a secure transmission of data for Cluster-based WSNs (CWSNs) is studied, where the clusters are formed dynamically and infrequently. Basically protocols for CWSNs, called SET-IBS (Secure and Efficient data Transmission Identity-Based digital Signature) scheme and SET-IBOOS (Identity-Based Online/Offline digital Signature) scheme, correspondingly. In SET-IBS, security relies on the hardness of the Dill-Hellman difficulty in the pairing area. Data aggregation is the process of abbreviation and combining sensor data in order to reduce the amount of data transmission in the network.