In the rapidly evolving field of cloud computing, data security is a significant concern due to the vulnerability of centralized key management and potential unauthorized access. This paper introduces a novel two-phase solution aimed at enhancing cloud data security through dynamic encryption and blockchain-based key management. The first phase utilizes dynamic Advanced Encryption Standard (AES) encryption, where unique keys are generated for each file, ensuring robust file-level security. In the second phase, blockchain technology is employed to securely store encryption keys, maintaining data integrity and decentralized control. Elliptic Curve Cryptography (ECC) further strengthens security during transmission and file sharing. By integrating dynamic AES encryption with blockchain key management, this approach addresses the limitations of traditional cloud security methods, offering enhanced protection against key compromise and unauthorized access. The proposed solution is scalable and adaptable, making it a valuable asset in ensuring data security in modern cloud infrastructures.

KEYWORDS: Elliptic Curve Cryptosystem (ECC), Advanced Encryption Standard (AES) , Cloud Computing, Data security.