The surge in demand for optimization of resource usage, reliability, and avoidance of vendor lock-in has led to a rise in the use of multi-cloud environments. The spread nature of these environments poses challlenging issues regarding security, specifically data confidentiality, integrity and availability. In this paper, we present a monitoring multi-layered encryption methodology for multi-cloud environments. Our mechanism implements a multi-cloud architecture with an adaptive selection mechanism that encrypts data encrypts on the basis of sensitivity, size of the data and available computational resources. The proposed methodology utilizes a hybrid architecture that employs Elliptic Curve Cryptography (ECC) for key exchange, symmetric encryption for data protection, and zero-knowledge proofs for authentication. Evaluation results indicate a substantial positive difference in computational efficiency, levels of security achieved, and scalability in comparison to the traditional approaches based on the RSA algorithm. The implementation offers strong defense against classical as well as emerging quantum threats while being resource efficient in multi-cloud environments.