Analysis of Reusability of Secure Sketches and Fuzzy Extractors

Secure sketches and fuzzy extractors enable the use of biometric data in cryptographic applications by correcting errors in noisy biometric readings and producing cryptographic materials suitable for authentication, encryption, and other purposes. Such constructions work by producing a public sketch, which is later used to reproduce the original biometric and all derived information exactly from a noisy biometric reading. It has been previously shown that release of multiple sketches associated with a single biometric presents security problems for certain constructions. We continue the analysis to demonstrate that all other constructions are also prone to similar problems and cannot be safely reused even in the presence of very weak adversaries.