A Layered Secret Sharing Scheme for Automated Profile Sharing in OSN Groups.

We propose a novel Layered secret sharing scheme and its application to Online Social Networks (OSNs). In current, commercially offered OSNs, access to users' profile information is managed by the service provider e.g. Facebook or Google+, based on the user defined privacy settings. A limited set of rules such as those governing the creation of groups of friends as defined by the user (e.g. circles, friend groups or lists) allow the users to define different levels of privacy, however they are arguably complex and rely on a trusted third party (the service provider) to ensure compliance. The proposed scheme enables automated profile sharing in OSN groups with fine grained privacy control, via a multi-secret sharing scheme comprising layered shares, created from user's profile attributes (multiple secrets), that are distributed to group members; with no reliance on a trusted third party. The scheme can be implemented via e.g. a browser plugin, enabling automation of all operations for OSN users. We study the security of the scheme against attacks aiming to acquire knowledge about user's profile. We also provide a theoretical analysis of the resulting level of protection for specific (privacy sensitive) attributes of the profile.