Interoperable healthcare IT systems are leveraged upon 5G enabled interacted IoMT devices and database servers, yet most existing security frameworks still rely on static keys that cannot cope with array of cyber threats, vulnerabilities, and attack vectors. To address this gap, we presented an environment-aware security framework that fused together with ECC-based mutual authentication and signcryption mechanism. The proposed approach uses environmental values such temperature as a natural, dynamic source of entropy to introduce randomness in the security process, especially in driving session oriented cryptographic keys, allowing each transmission to be securely binds with the device’s operating context. In the proposed work, signcryption process binds the encryption and signing into a single step,that reduces the packet size and computational cost of resource limited sensing and gateway devices. On the other side, a Zero Trust Data Gateway unsigncrypts, verifies, and forwards messages to a patient-centric ZTA module for granting or rejecting permission based on received request within specific context. The experiment show that proposed approach achieves faster execution, lower overhead, and stronger replay resistance than traditional RSA or Elliptic Curve Cryptography- Elliptic Curve Digital Signature Algorithm (ECCECDSA) alternatives. Overall, proposed work concludes a practical path toward secure, context-aware communication in next-generation healthcare environments.