Abstract: Cloud computing offers a new way of resources and services like storage, computing and application get access on the demand of customer. Where rapidly increase of using cloud computing in society drew the attention of security and privacy of data. Therefore the sharing of resources and data over the unauthorized public network will be more unsecure to transfer from user to cloud and vice versa on the unauthorized public network because of malicious attacks like man in middle, reply attacks etc. Other one we cannot trust every Cloud service provider (CSP) and keep our data in there cloud. So in this paper we proposed a method that Kerberos and identity based encryption used for secure data transfer over the untrusted public network and provide confidentiality to data which is uploaded in cloud. This maintain a superior security with the combined approach of Kerberos and IBE in cloud computing because no such a method exists and this method provides features of authentication, confidentiality, integrity, privacy and security to Cloud Service Providers and cloud users. 
Keywords: Cloud computing, security, Kerberos authentication, private key generator, identity based encryption.