Cloud computing, by definition, provides on-demand services-perhaps the most revolutionary change in the provisioning of resources for an enterprise in recent decades. The rise of the IoT has ushered in a new age of collaborative computing formed by multiple networks of smart sensors and devices capable of generating and processing huge data volumes. On the other hand, this creates another set of problems related to data volume and security, making the security mechanisms even more capitalized. In this research, a novel Scalable and Secure Cloud Architecture (SSCA) is proposed, integrating IoT and advanced cryptographic mechanisms to design highly available, multi-user cloud systems. The architecture works in a distributed mode in the cloud, allowing several cloud nodes to serve user requests efficiently while using the Multicast and Broadcast Rekeying Algorithm (MBRA) to uphold privacy and confidentiality of users. The proposed cryptosystem combines MBRA, Post-Quantum Cryptography (PQC), and blockchain technologies. The IoT devices gather data in a distributed sensing network secured by MBRA PQC encryption, while the blockchain ensures immutability and distributed integrity of the data.