In spite of the release of Windows 8 and Windows Server 2012, the popularity of Windows 7 is without parallel among all operation systems nowadays. It is widely recognized that Windows 7 has relatively satisfying security performance, especially when compared with Windows Vista. However, the password problems in Windows 7 are still big concerns to many Windows 7 users. For example, some users may forget their login passwords on a regular basis so that they have to face the problem