Enhancing Distributed Data Storage Security for Cloud Computing Using TPA and AES Algorithm Cloud computing model is very exciting model especially for business peoples. Many business peoples are getting attracted towards cloud computing model because of the features easy to manage, device independent, location independent. But this cloud models comes with many security issues. A business person keeps crucial information on cloud, so security of data is crucial issue as probability of hacking and unauthorised access is there. Also availability is a major concern on cloud. This paper, discusses the file distribution and SHA-1 technique. When file is distributed then data is also segregated into many servers. So here the need of data security arises. Every block of file contains its own hash code, using hash code which will enhance user authentication process, only authorized person can access the data. Here, the data is encrypted using advanced encryption standard, so data is successfully and securely stored on cloud. Third party auditor is used for public auditing. This paper discusses the handling of some security issues like Fast error localization, data integrity, data security. The proposed design allows users to audit the data with lightweight communication and computation cost. Analysis shows that proposed system is highly efficient against malicious data modification attack and server colluding attack. Performance and extensive security analysis shows that proposed systems are provably secure and highly efficient.