Preserving privacy with user-controlled sharing of verified information
Bauer, David Allen
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Personal information, especially certified personal information, can be very valuable to its subject, but it can also be abused by other parties for identify theft, blackmail, fraud, and more. One partial solution to the problem is credentials, whereby personal information is tied to identity, for example by a photo or signature on a physical credential. We present an efficient scheme for large, redactable, digital credentials that allow certified personal attributes to safely be used to provide identification. A novel method is provided for combining credentials, even when they were originally issued by different authorities. Compared to other redactable digital credential schemes, the proposed scheme is approximately two orders of magnitude faster, due to aiming for auditability over anonymity. In order to expand this scheme to hold other records, medical records for example, we present a method for efficient signatures on redactable data where there are dependencies between different pieces of data. Positive results are shown using both artificial datasets and a dataset derived from a Linux package manager. Electronic credentials must of course be held in a physical device with electronic memory. To hedge against the loss or compromise of the physical device holding a user's credentials, the credentials may be split up. An architecture is developed and prototyped for using split-up credentials, with part of the credentials held by a network attached agent. This architecture is generalized into a framework for running identity agents with various capabilities. Finally, a system for securely sharing medical records is built upon the generalized agent framework. The medical records are optionally stored using the redactable digital credentials, for source verifiability.