The blockchain-based Internet of Things (IoT) application combines the distributed ledger, encryption security, and decentralization features of blockchain technology, as well as the ability of IoT devices to connect and collect data on a large scale. This combination can address some key issues in the field of the IoT, such as data privacy, security, trust, and interoperability between devices. However, the computing power, storage space, and energy supply of IoT devices are often limited, and traditional encryption algorithms are not applicable. This paper proposes a new lightweight block cipher, SPOR. SPOR aims to further improve the security and resource reuse efficiency of encryption algorithms through innovative S-box design and key schedules. Specifically, SPOR’s s-box has lower boomerang uniformity, higher algebraic terms and degrees, and no linear structure inside, significantly increasing nonlinearity and complexity; its key schedule eliminates complex logical operations and adopts random methods such as circular shifting and index selection, reducing the hardware implementation area of the algorithm. The experimental results show that SPOR has a good strict avalanche effect and that hardware implementation requires only 1211 GEs.