Abstract: An online system determines whether a request for creating a session with the online system is suspicious. The online system associates a user account with a mobile key of a mobile device and geographical locations of the mobile device. The mobile key comprises unique identifier of the mobile device that is permanently stored on the mobile device. Upon receiving a request to create a session for the user account, the online system compares information associated with the user request with information describing the mobile device. For example, information associated with the user request can be a location determined by mapping internet protocol addresses obtained from the request. The online system determines whether the request is suspicious based on the comparison. If the online system determines that the request is suspicious, the online system may require enhanced authentication before granting the request.

Abstract: Images uploaded by users of a social networking system are analyzed to determine signatures of cameras used to capture the images. A camera signature comprises features extracted from images that characterize the camera used for capturing the image, for example, faulty pixel positions in the camera and metadata available in files storing the images. Associations between users and cameras are inferred based on actions relating users with the cameras, for example, users uploading images, users being tagged in images captured with a camera, and the like. Associations between users of the social networking system related via cameras are inferred. These associations are used beneficially for the social networking system, for example, for recommending potential connections to a user, recommending events and groups to users, identifying multiple user accounts created by the same user, detecting fraudulent accounts, and determining affinity between users.

Abstract: An online services system includes a mechanism for providing user confidence information to an external data consumer, and for determining user contribution quality. Using stored information about user actions and interactions, user confidence is evaluated for one or more parameters associated with the validity of the user's account and/or quality of the user's contributions to the online services system. Confidence values are assigned to each parameter, and the values are exposed to external data consumers. Using stored information, user actions and interactions are correlated with contribution quality to produce a metric indicative of user contribution quality. Users with low quality parameter metrics may have their contributions shown to a smaller audience or have a lower prominence in a news feed.

Abstract: Users of an online system are authenticated based on signatures of cameras that were used to capture images uploaded to the online system. Users of an online system upload photos taken from their cameras. The online system extracts characteristic information about the camera that captured the photos. This information includes a mapping of faulty pixels, metadata included with the photos, a naming convention, and the like. The online system stores an association between the user and the camera. This association is used for authentication of the user. For authentication, the user is asked to upload new photos taken from the camera that the user used previously. The information extracted from the newly uploaded photos is matched against stored information of cameras used previously by the user. The user is successfully authenticated if the camera used for the newly uploaded photos matches a previously stored camera.

Abstract: Users of social networking system are provided with user interface elements permitting the user to post comments on pages within the social networking system. Pages may be provided for any non-user entity, including for example, pages for businesses, products, concepts, etc. Embodiments provided herein permit page moderators to ban certain content from being displayed on a page. For example, the social networking system may receive a list of proscribed content and block comments containing the proscribed content by reducing the distribution of those comments to other viewing users. However, the social networking system may display the blocked content to the commenting user such that the commenting user is not made aware that his or her comment was blocked, thereby providing fewer incentives to the commenting user to spam the page or attempt to circumvent the social networking system filters.

Abstract: An online services system includes a mechanism for providing user confidence information to an external data consumer, and for determining user contribution quality. Using stored information about user actions and interactions, user confidence is evaluated for one or more parameters associated with the validity of the user's account and/or quality of the user's contributions to the online services system. Confidence values are assigned to each parameter, and the values are exposed to external data consumers. Using stored information, user actions and interactions are correlated with contribution quality to produce a metric indicative of user contribution quality. Users with low quality parameter metrics may have their contributions shown to a smaller audience or have a lower prominence in a news feed.

Abstract: Users of an online system are authenticated based on signatures of cameras that were used to capture images uploaded to the online system. Users of an online system upload photos taken from their cameras. The online system extracts characteristic information about the camera that captured the photos. This information includes a mapping of faulty pixels, metadata included with the photos, a naming convention, and the like. The online system stores an association between the user and the camera. This association is used for authentication of the user. For authentication, the user is asked to upload new photos taken from the camera that the user used previously. The information extracted from the newly uploaded photos is matched against stored information of cameras used previously by the user. The user is successfully authenticated if the camera used for the newly uploaded photos matches a previously stored camera.

Abstract: Users of an online system are authenticated based on signatures of cameras that were used to capture images uploaded to the online system. Users of an online system upload photos taken from their cameras. The online system extracts characteristic information about the camera that captured the photos. This information includes a mapping of faulty pixels, metadata included with the photos, a naming convention, and the like. The online system stores an association between the user and the camera. This association is used for authentication of the user. For authentication, the user is asked to upload new photos taken from the camera that the user used previously. The information extracted from the newly uploaded photos is matched against stored information of cameras used previously by the user. The user is successfully authenticated if the camera used for the newly uploaded photos matches a previously stored camera.

Abstract: Users of an online system are authenticated based on signatures of cameras that were used to capture images uploaded to the online system. Users of an online system upload photos taken from their cameras. The online system extracts characteristic information about the camera that captured the photos. This information includes a mapping of faulty pixels, metadata included with the photos, a naming convention, and the like. The online system stores an association between the user and the camera. This association is used for authentication of the user. For authentication, the user is asked to upload new photos taken from the camera that the user used previously. The information extracted from the newly uploaded photos is matched against stored information of cameras used previously by the user. The user is successfully authenticated if the camera used for the newly uploaded photos matches a previously stored camera.