Poster: Fine-Grained Access Control with Efficient Range Comparison for Outsourced Data

Ciphertext-policy attribute-based encryption (CP-ABE) offers a promising approach to enforce fine-grained access control over outsourced data through cryptographic functions. It enables data owners to formulate access policies by specifying attribute constraints within the ciphertext, ensuring that the data user's attributes comply with the policy for successful decryption. While CP-ABE is primarily designed for descriptive attributes, current access control scenarios require the inclusion of range comparisons. However, existing CP-ABE implementations lack an efficient mechanism to model numeric range attributes for related range constraints in the access policy. To address this, we translate the verification of range constraint against the user's numeric attribute into a set intersection problem. Specifically, we utilize 0-encoding and 1-encoding properties to convert range constraint expressions in the access policy and corresponding numeric attributes in the user's key into sets with optimized sub-attributes. This minimizes the computational and storage overhead of ciphertext and private keys, substantially reducing the matching operations needed for access policy verification in practical range-based CP-ABE.