As the Internet of Things (IoT) continues to grow at an exponential rate, securing the transmission of data among various types of heterogeneous resources with limited capacity has become more challenging than ever before. To address this challenge, we propose a lightweight cryptographic framework that integrates optimized symmetric and asymmetric encryption algorithms and secure communication protocols, which can significantly enhance the security of IoT communications. Specifically, we describe an architecture for our new cryptographic framework that utilizes AES-128 and ECC-based key exchanges combined with dynamic tokenization and hashing for integrity verification - to provide confidentiality, authentication, and integrity of the communicated data. In addition, our experimental results show that more than double (37%) the cryptographic throughput compared to other traditional methods; over 22% less memory overhead than traditional methods; and 19% less energy consumed to process the same amount of data as traditional methods. Furthermore, the system reduces the potential for man-in-the-middle and spoofing attacks by 46% when using secure MQTT or HTTPS basis of transmission layers within the overall architecture.