Evaluation of Privacy-ABC Technologies – A Study on the Computational Efficiency
Fatbardh Veseli and Jetzabel Serna
Privacy-enhancing attribute-based credential (Privacy-ABC) technologies use different cryptographic methods to enhance the privacy of the users. This results in important practical differences between these technologies, especially with regard to efficiency, which have not been studied in depth, but is necessary for assessing their suitability for different user devices and for highly dynamic scenarios. In this paper, we compare the computational efficiency of two prominent Privacy-ABC technologies, IBM’s Idemix and Microsoft’s U-Prove, covering all known Privacy-ABC features. The results show that overall presentation is in general is more efficient with Idemix, whereas U-Prove is more efficient for the User side (proving) operations during the presentation, and overall when there are more attributes in a credential. For both technologies we confirmed that inspectability, non-revocation proofs, and inequality predicates are costly operations. Interestingly, the study showed that equality predicates, the number of attributes in a credential, and attribute disclosure are done very efficiently. Finally, we identified a number of specific trust issues regarding Privacy-ABC technologies.