With the development of network and communication systems in large areas in the world, this leads to increase security problems in transmission of data such as data leakage, modification, unauthorized access, and attacks. There are many types of techniques that are used to prevent these problems and protect data. One of these techniques is a stream cipher which considered the strongest and fastest method used in encryption and decryption process. In this study presented a new design for the stream cipher to protect mobile data. The strength of stream cipher depends on it is' key. There are several methods to generate key. We used three types of generator. Then, it used the combiner to convert them into a nonlinear Boolean function in order to make the generator key more secure. To implement a new generator key by using these three kinds, we used four LFSRs and one of NLFSRs or FCSRs to produce five variables Boolean function. These variables will be as an input to the combiner function. Finally, we tested the generator and submitted it to the randomness tests that is publicly available in the National Institute of Standards and Technology (NIST).