Login authentication method and system, and webpage login method and system

The invention relates to a login authentication method and a login authentication system. The method comprises the following steps: receiving user identity identifier sent by a client; searching for atarget image matching the identity identifier from an image library according to the user identity identifier, and generating an interference image of the target image; sending the target image and the interference image to the client for display; and receiving a selection operation of a user on the target image and the interference image fed back by the client, and authenticating the identity ofthe user. By adoption of the login authentication method, the problem of low accuracy caused by the traditional technology is solved, the user performs image selection in a large number of interference images to authenticate the login identity of the user, so that the accuracy of login authentication can be improved, and meanwhile, the security of login authentication is also guaranteed. The invention further provides a w