Isogeny-based post-quantum proxy signature for Internet of Things

The rapid growth of the Internet of Things (IoT) introduces challenges in secure authentication and delegation due to the limited computational capabilities of devices. Proxy signature schemes offer an effective solution by enabling controlled delegation of signing rights to more capable entities, such as gateway nodes. However, most existing schemes rely on classical assumptions that are likely to be broken by quantum adversaries. In this work, we address these challenges by proposing an isogeny-based post-quantum proxy signature scheme, CSI-PS. The scheme leverages the hardness of the Group Action Inverse Problem (GAIP) to provide post-quantum security in a gateway-assisted IoT setting. In the proposed construction, expensive isogeny-based operations are assigned to resource-capable entities such as IoT gateways, while sensor nodes only transmit data to the gateway. We provide explicit storage, communication, Merkle-authentication, key-distribution, and setup-cost accounting to clarify the practical deployment profile of the construction. Our analysis shows that the proposed scheme strikes an effective balance between security and efficiency in terms of computation and communication overhead, along with provable security under the EUF-CMA notion.