Cloud computing is a fast-growing technology that aims to provide ubiquitous and easy access to a shared collection of configurable computing resources to consumers as per their requirements. However, alongside its fast development and promises comes critical security challenges. Security concerns represent a dynamic field of research and addressing these concerns effectively is very important to prevent security threats and attacks, which can have drastic consequences for both service providers and consumers. This paper discusses cloud computing principles, cloud computing security vulnerabilities, threats and attacks with their mitigation techniques, the use of cryptography techniques in securing information and communication to prevent unauthorized access, and evolving research challenges. Moreover, an enhanced cryptographic algorithm is introduced, which builds upon the traditional Caesar Cipher technique, extending its applicability to numeric values.