Abstract: 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 user data 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 user data, maintaining data integrity and decentralized control, while ensuring transparency and immutability. Additionally, the system incorporates a security mechanism where if a user fails to log in after multiple attempts, an email is sent with a randomly generated password and the system’s IP address. The user can then log in with the generated password and change it for further access. Elliptic Curve Cryptography (ECC) further strengthens security during transmission and file sharing. By integrating dynamic AES encryption with blockchain for user data storage and enhanced login protection, this approach addresses the limitations of traditional cloud security methods, offering protection against unauthorized access, key compromise, and brute-force attacks. 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, Blockchain, User Data Management.