Abstract: A method may be performed using a server. The method may include receiving an identity authentication request associated with a user, generating authentication information based on the identity authentication request, and generating candidate information based on the authentication information such that the authentication information is a subset of the candidate information. The candidate information may be displayed at a randomly selected location. The user may provide input through a graphic input interface to select the authentication information from among the candidate information.

Abstract: When a security authentication request sent by a terminal is received, an identity authentication solution includes acquiring network environment information and user behavior data according to the security authentication request, then determining, according to the network environment information and the user behavior data, whether a current operation is a machine attack, and acquiring a CAPTCHA of a predetermined type according to a predetermined policy and delivering the CAPTCHA to the terminal if the current operation is a machine attack, to perform identity authentication, or determining that security authentication succeeds if the current operation is not a machine attack.

Abstract: When a security authentication request sent by a terminal is received, an identity authentication solution includes acquiring network environment information and user behavior data according to the security authentication request, then determining, according to the network environment information and the user behavior data, whether a current operation is a machine attack, and acquiring a CAPTCHA of a predetermined type according to a predetermined policy and delivering the CAPTCHA to the terminal if the current operation is a machine attack, to perform identity authentication, or determining that security authentication succeeds if the current operation is not a machine attack.