Toward Efficient Cloud Data Sharing: A Pairing-Free ABE Scheme with Redefinable Weighted Access Policy

Attribute-based encryption (ABE) provides a robust mechanism for fine-grained access control, making it an ideal candidate for secure cloud data sharing. However, existing schemes often incur significant computational overhead, hindering their large-scale deployment, especially on resource-constrained nodes. In this work, we propose a practical ABE scheme that simultaneously simplifies access policy structures and enhances overall efficiency. By introducing a weighted access policy, our scheme achieves rich expressiveness while maintaining a compact logic structure, offering enhanced flexibility through the redefinability of attribute weights. Notably, the proposed construction is pairing-free and yields small-size ciphertexts and private keys compared to traditional tree-based models. Security analysis demonstrates that our scheme is selectively secure against chosen-ciphertext attacks. Extensive simulation results show that encryption and decryption latency is reduced to nearly 10 ms when 20 attributes are involved, which is a typical requirement in cloud data sharing scenarios. This validates the efficiency of our scheme in resource-constrained environments.