The system is constructed with the formalization of honest and malicious users, which are specifically exemplified in Sybil Guard as nodes. The way to recognize potential attackers is by identifying how many identities one user occupies. For example, honest users have only one identity while the attacker has many identities, which the protocol detects.
As Yu and his contributing experts assert, ‘all honest nodes and sybil nodes in the system form a social network’ (Yu et al., 2008), which is precisely demonstrated in the given figure.
Subsequently, if two users are linked without corruptive intent and form an honest relationship, we call that connection an edge. In contrast, any honest user or node that connects with an attacker forms an attack edge. In the process of regulating potential attackers, this graph proves to be effective. Not only does it limit ‘the number of attack edges’ (Yu et al., 2008), it also concludes with the proposition that reliable users don’t need to form any bonds because they already have established friends, whereas, the intention of sybil attackers is to add friends which inevitably dispatches several attack edges. This model allows Sybil Guard to defend social networks against sybil intruders by obstructing and restricting the number of ‘false’ relationships one attacker creates.
Yu, H., Kaminsky, M., Gibbons, P. B., & Flaxman A.D. (2008). SybilGuard: Defending against sybil attacks via social networks. IEEE/ACM Transactions on Networking, 16(3), 576-589.