Security plays a very important role in the life of every living being. Today, in the ‘Technology’ engulfed businesses, data security is crucial for users and vendors alike. Cloud computing as a technology is the driving force behind all the financial transactions being completed every second across the globe. In the current context, Cloud data security is crucial and is of utmost importance. Data Security in the cloud refers to the technologies, policies, services, security controls that protect data in the cloud from loss, leakage or misuse through security breaches and unauthorized access. Securing data in the cloud is essential in e-commerce because attacks on the data can result in loss of revenue for businesses. Cyber criminals use advanced tools and techniques to steal information from the cloud servers for financial gain and other unscrupulous benefits. Securing data while it is at rest or in transit is most important for businesses. Efficient Data security tools and techniques must be applied to protect the data resident in the cloud. This paper closely examines the Issues and challenges of Data Security in Cloud Computing with reference to e-commerce. Keywords: Challenges, Cloud Computing, Data Security, E-Commerce, Public Cloud.