Sybil-Proof Diffusion Auction in Social Networks
This addresses a security vulnerability in dynamic social network markets for buyers, though it is incremental as it builds on existing diffusion auction mechanisms.
The paper tackles the problem of Sybil attacks in diffusion auctions over social networks, where buyers can create fake nodes to manipulate outcomes, and proposes two mechanisms (STM and SCM) that achieve Sybil-proofness and incentive compatibility with a mild sacrifice in social welfare and revenue.
A diffusion auction is a market to sell commodities over a social network, where the challenge is to incentivize existing buyers to invite their neighbors in the network to join the market. Existing mechanisms have been designed to solve the challenge in various settings, aiming at desirable properties such as non-deficiency, incentive compatibility and social welfare maximization. Since the mechanisms are employed in dynamic networks with ever-changing structures, buyers could easily generate fake nodes in the network to manipulate the mechanisms for their own benefits, which is commonly known as the Sybil attack. We observe that strategic agents may gain an unfair advantage in existing mechanisms through such attacks. To resist this potential attack, we propose two diffusion auction mechanisms, the Sybil tax mechanism (STM) and the Sybil cluster mechanism (SCM), to achieve both Sybil-proofness and incentive compatibility in the single-item setting. Our proposal provides the first mechanisms to protect the interests of buyers against Sybil attacks with a mild sacrifice of social welfare and revenue.