Dynamic fine-grained access control for smart contracts based on improved attribute-based signature

Access control for smart contracts is the primary security mechanism for protecting users’ digital assets. However, existing solutions have defects in control granularity and flexibility, and a large number of resource-constrained blockchain nodes impose stringent and lightweight requirements on access control mechanisms. Therefore, achieving secure, efficient, and flexible access control for smart contracts has become a key issue that blockchain applications need to address. Based on the attribute-based access control model, this paper utilizes attribute-based signature (ABS) to achieve flexible and efficient access control for smart contracts. First, to solve the problem that existing ABS schemes are not suitable for resource-constrained blockchain nodes because they are mainly based on expensive bilinear pairing, a lightweight no-pairing attribute-based signature scheme called LABS is designed to make the signature size independent of the user’s attribute set and decouple the signature from the verification policy. Then, based on the LABS scheme, a smart contract-oriented access control mechanism (DSCABS) is proposed to ensure that only legitimate users whose attributes satisfy the access policy can be authorized to invoke smart contracts. Also, DSCABS supports dynamic updates of user rights and contract access policies without modifying or redeploying the smart contract. Finally, the effectiveness of the proposed scheme is verified by simulation experiments.