MediCrypt-DDT: Cross-domain Distributed Dynamic Threshold Attribute-based Encryption for Medical Healthcare System

The digital transformation of healthcare necessitates advanced mechanisms for secure, privacy-preserving data sharing. Traditional methods struggle with the complexities of modern application scenarios such as cross-domain collaboration. We propose a privacy-preserving medical healthcare intelligent system built upon a novel Distributed Dynamic Threshold Attribute-based Encryption (DDTABE) scheme. Our DDTABE scheme is proven to achieve IND-CPA security under the aMSE-DDH hardness assumption in the random oracle model. The resulting system facilitates secure cross-domain medical data sharing and allows medical personnel to join dynamically for flexible collaboration. A key feature is its robustness as it resists unauthorized attributes through a verifiable mechanism. Performance analysis and experimental comparisons demonstrate the efficiency of our approach. Specifically, our scheme exhibits significant advantages in the running times of the Setup, Encrypt, and Decrypt algorithms compared to existing work, as the sizes of attribute sets in keys and policies grow, while maintaining constant ciphertext complexity.