Abstract: By introducing social login, the platform can attract internet users to log in. Meanwhile, "social login" can improve the platform's advertising targeting ability because of sharing users' personal data. However, because of users' privacy concerns, social login may cause users not willing to use the platform. Hence, it is important to study the effects of internet users' privacy concerns on social login to help the platform make its social login strategy. So far, the existing literatures have not solved the impacts of user's choice of social login on the platform/enterprise's social login provision, and the literatures on platform/enterprise's choice of social login has not considered the influence of user's privacy concerns.
In this paper, the effects of Social Login on the platform's targeted targeting strategy are studied in a monopoly market. There are two types of Internet users on one side of the platform, the first type whoare called "privacy sensitive users" with high privacy concerns andthe second type who are called "privacy neutral users" with low privacy concerns.Meanwhile, there are plenty of advertisers on the other side of the platform. These advertisers choose to targeted advertise by measuring the platform's targeting ability, which is determined by advertising targeting capability and the number of Internet users on the platform. A four stage game-theoretic modelis constructed:In the first stage, the platform determines whether to open Social Login. In the second stage, the platform determines its advertising targeting capability. In the third stage, advertises determined whether to targeted advertise on the platform or not. In the fourth stage, Internet users determine whether to login the platform or not and further choose the way to login, using Social Login or Platform Account Login.
The equilibriums are derived through backward induction method. By analyzing the equilibriums, propositions were given from three thresholds. Firstly, due to the existence of user privacy concerns, it is suggested thatthe platform maynot provide social login. If the proportion of privacy sensitive users is relatively high, whensocial login brings a higher targeting promotion to the platform, providing social login will reduce the platform's revenue.Secondly, it also indicated that ifthe platform provides social login, social login has the following effects on the platform's advertising targeting capabilitywhen there are more privacy sensitive users in the market:the platform's advertising targeting capabilityincreases first and then decreases with the increase of targeting promotion. When there are more privacy neutral users in the market, strengthening targeting promotion discouragesthe platform from increasingadvertising targeting capability. In addition, with the strengthening targeting promotion, the platform's profit is concave intargeting promotion. Thirdly, it is shown that when targeting promotion brought by social login is low, social login cannot help the platform attract more users.

Key words: privacy concerns, social login, information sharing, targetingpromotion, targeting capability