View source

'''Time and Place''': 10:00  Lindstedtsvägen 4, 5th floor, room 1537

'''Title''': Encryption for Peer-to-Peer Social Network - Oleksandr Bodriagov 

'''Abstract''':

To address privacy concerns over online social networking
services, several distributed alternatives have been proposed. These
peer-to-peer (P2P) online social networks do not rely on centralized
storage of user data. Instead, data can be stored not only on a computer
of a profile owner but almost anywhere (friends’ computers, random peers
from the social network, third-party external storage, etc.). Since the
external storage is often untrusted or only semi-trusted, encryption
plays a fundamental role in security of P2P social networks.
Encryption, however, also adds some overhead in both the time and space
domains. To be scalable, a system that relies heavily on encryption
should use as efficient algorithms as possible. It also needs to provide
the functionality of changing access rights at reasonable cost, and,
crucially, the system should preserve privacy properties itself. That
is, beyond user data confidentiality, it has to protect against
information leakage about users’ access rights and traffic analysis.
In this paper we explore the requirements of encryption for P2P social
networks in detail and propose a list of criteria for evaluation. We
then compare a set of approaches from the literature according to these
criteria. We find that none of the current P2P architectures for social
networks manages to achieve secure, efficient, 24/7 access control
enforcement and data storage. They either rely on trust, require
constantly running servers for each user, use expensive encryption, or
fail to protect privacy of access information. In the search for a
solution that better fulfils the criteria, we found that some broadcast
encryption (BE) schemes exhibit several desirable properties.
We thus propose to use BE schemes with high performance encryption/decryption 
regardless of the number of identities/groups for an
efficient encryption-based access control in the P2P environment. We
define relevant properties for the BE schemes to be used in the P2P
social network scenario and describe advantages that such schemes have
compared to encryption techniques used in existing P2P architectures.