Cloud computing is a newfound rapid growth in IT industry during recent several advantages of this technology there ar as security and privacy that affect the r computing models. Access control and user aut most important security issues in cloud com the research has been prepared to pro information about this security concerns a about the identified issues in access c authentication researches. Therefore, cloud c and disadvantages have been explained in t second part reviewed some of access c authentication algorithms and identifyin weaknesses of each algorithm. The main aim considering limitations and problems of previ research area to find out the most challengi control and user authentication algorithms.