Data is key: introducing the data-based access control paradigm

According to the Jericho forum, the trend in information security is moving the security perimeter as close to the data as possible. In this context, we suggest the idea of data-based access control, where decryption of data is made possible by knowing enough of the data. Trust is thus based on what someone already knows. A specific problem is defined as follows: given n pieces of data, an agent is able to recover all n items once she knows k of them. The problem is similar to both secure sketches and secret sharing, and we show that both can be used as a basis for constructions. Examples of possible applications are granting access without credentials, recovering forgotten passwords and sharing personal data in social networks.