Abstract: A social networking system performs account recovery for a user with the help of the user's connections (e.g., friends). The social networking system selects connections of the user based on information indicating likelihood of real-world interactions between the user and the selected connections. Access codes are sent to the selected connections and the user instructed to obtain access codes from the selected connections via a communication that is outside the social networking system, for example, via phone. The user provides the access codes obtained from the selected connections to the social networking system. If the access codes provided by the user match the access codes sent to the selected connections, the user is granted access to the account. Real-world interactions between two users are determined based on sharing of devices between the users or information indicating presence of the users in the same place during same time interval.

Abstract: A social networking system performs account recovery for a user with the help of the user's connections (e.g., friends). The social networking system selects connections of the user based on information indicating likelihood of real-world interactions between the user and the selected connections. Access codes are sent to the selected connections and the user instructed to obtain access codes from the selected connections via a communication that is outside the social networking system, for example, via phone. The user provides the access codes obtained from the selected connections to the social networking system. If the access codes provided by the user match the access codes sent to the selected connections, the user is granted access to the account. Real-world interactions between two users are determined based on sharing of devices between the users or information indicating presence of the users in the same place during same time interval.

Abstract: A social networking system identifies relationships between friends of a target user that are likely to be unexpected to the target user. To identify an unexpected relationship among a user's friends, the social networking system determines a measure of unexpectedness for pairs of connections of the target user and selects pairs of connections for presentation to the user based on the measure of unexpectedness. The measure of unexpectedness of a relationship between a pair of friends is inversely related to a number of connections between each of the pair of friends and the target user. Information describing the pair of unexpected friends may be presented to a target user along with content relating the two friends, such as photos in which both friends are tagged, events attended by the unexpected friends together, or places both unexpected friends checked-in at the same time.

Abstract: User login information submitted as part of an attempt to log into a computer system is evaluated for unauthorized or illegitimate use based on indicators of suspicious behavior. Example indicators of suspicious behavior include whether the login information is known to have been compromised, whether the login attempt originates from a network source or a physical source that has previously originated an attempt to log in using login information known to have been compromised, and whether multiple login attempts using the login information from multiple users has originated from the source. A suspicion index can be calculated based on the presence of the indicators of suspicious behavior. The system can require enhanced authentication based on the measurement of suspicious behavior.

Abstract: A social networking system performs account recovery for a user with the help of the user's connections (e.g., friends). The social networking system selects connections of the user based on information indicating likelihood of real-world interactions between the user and the selected connections. Access codes are sent to the selected connections and the user instructed to obtain access codes from the selected connections via a communication that is outside the social networking system, for example, via phone. The user provides the access codes obtained from the selected connections to the social networking system. If the access codes provided by the user match the access codes sent to the selected connections, the user is granted access to the account. Real-world interactions between two users are determined based on sharing of devices between the users or information indicating presence of the users in the same place during same time interval.

Abstract: A social networking system performs account recovery for a user with the help of the user's connections (e.g., friends). The social networking system selects connections of the user based on information indicating likelihood of real-world interactions between the user and the selected connections. Access codes are sent to the selected connections and the user instructed to obtain access codes from the selected connections via a communication that is outside the social networking system, for example, via phone. The user provides the access codes obtained from the selected connections to the social networking system. If the access codes provided by the user match the access codes sent to the selected connections, the user is granted access to the account. Real-world interactions between two users are determined based on sharing of devices between the users or information indicating presence of the users in the same place during same time interval.

Abstract: A social networking system performs account recovery for a user with the help of the user's connections (e.g., friends). The social networking system selects connections of the user based on information indicating likelihood of real-world interactions between the user and the selected connections. Access codes are sent to the selected connections and the user instructed to obtain access codes from the selected connections via a communication that is outside the social networking system, for example, via phone. The user provides the access codes obtained from the selected connections to the social networking system. If the access codes provided by the user match the access codes sent to the selected connections, the user is granted access to the account. Real-world interactions between two users are determined based on sharing of devices between the users or information indicating presence of the users in the same place during same time interval.

Abstract: User login information submitted as part of an attempt to log into a computer system is evaluated for unauthorized or illegitimate use based on indicators of suspicious behavior. Example indicators of suspicious behavior include whether the login information is known to have been compromised, whether the login attempt originates from a network source or a physical source that has previously originated an attempt to log in using login information known to have been compromised, and whether multiple login attempts using the login information from multiple users has originated from the source. A suspicion index can be calculated based on the presence of the indicators of suspicious behavior. The system can require enhanced authentication based on the measurement of suspicious behavior.

Abstract: User login information submitted as part of an attempt to log into a computer system is evaluated for unauthorized or illegitimate use based on indicators of suspicious behavior. Example indicators of suspicious behavior include whether the login information is known to have been compromised, whether the login attempt originates from a network source or a physical source that has previously originated an attempt to log in using login information known to have been compromised, and whether multiple login attempts using the login information from multiple users has originated from the source. A suspicion index can be calculated based on the presence of the indicators of suspicious behavior. The system can require enhanced authentication based on the measurement of suspicious behavior.

Abstract: A social networking system identifies relationships between friends of a target user that are likely to be unexpected to the target user. To identify an unexpected relationship among a user's friends, the social networking system determines a measure of unexpectedness for pairs of connections of the target user and selects pairs of connections for presentation to the user based on the measure of unexpectedness. The measure of unexpectedness of a relationship between a pair of friends is inversely related to a number of connections between each of the pair of friends and the target user. Information describing the pair of unexpected friends may be presented to a target user along with content relating the two friends, such as photos in which both friends are tagged, events attended by the unexpected friends together, or places both unexpected friends checked-in at the same time.

Abstract: User login information submitted as part of an attempt to log into a computer system is evaluated for unauthorized or illegitimate use based on indicators of suspicious behavior. Example indicators of suspicious behavior include whether the login information is known to have been compromised, whether the login attempt originates from a network source or a physical source that has previously originated an attempt to log in using login information known to have been compromised, and whether multiple login attempts using the login information from multiple users has originated from the source. A suspicion index can be calculated based on the presence of the indicators of suspicious behavior. The system can require enhanced authentication based on the measurement of suspicious behavior.

Abstract: Locating social networking system accounts for user of the social networking system permits the users to locate and access their accounts even if they cannot provide a user login ID or a login email address associated with their social networking system account. The social networking system locates a user account by receiving a user name associated with the user and a friend name of a friend connected to the user in the social networking system and identifying a user account wherein the identified user account has a user name matching the received user name and the identified user account is connected with another user in the social networking system who has a user name matching the received friend name.

Abstract: Locating social networking system accounts for user of the social networking system permits the users to locate and access their accounts even if they cannot provide a user login ID or a login email address associated with their social networking system account. The social networking system locates a user account by receiving a user name associated with the user and a friend name of a friend connected to the user in the social networking system and identifying a user account wherein the identified user account has a user name matching the received user name and the identified user account is connected with another user in the social networking system who has a user name matching the received friend name.

Abstract: A social networking system performs account recovery for a user with the help of the user's connections (e.g., friends). The social networking system selects connections of the user based on information indicating likelihood of real-world interactions between the user and the selected connections. Access codes are sent to the selected connections and the user instructed to obtain access codes from the selected connections via a communication that is outside the social networking system, for example, via phone. The user provides the access codes obtained from the selected connections to the social networking system. If the access codes provided by the user match the access codes sent to the selected connections, the user is granted access to the account. Real-world interactions between two users are determined based on sharing of devices between the users or information indicating presence of the users in the same place during same time interval.

Abstract: A social networking system performs account recovery for a user with the help of the user's connections (e.g., friends). The social networking system selects connections of the user based on information indicating likelihood of real-world interactions between the user and the selected connections. Access codes are sent to the selected connections and the user instructed to obtain access codes from the selected connections via a communication that is outside the social networking system, for example, via phone. The user provides the access codes obtained from the selected connections to the social networking system. If the access codes provided by the user match the access codes sent to the selected connections, the user is granted access to the account. Real-world interactions between two users are determined based on sharing of devices between the users or information indicating presence of the users in the same place during same time interval.