One embodiment of the present invention provides a system for automatically authenticating a user. During operation, the system receives a user's request for authentication. The system then extracts information associated with the user from user-specific information stored in an enterprise computer. The extracted user information does not explicitly relate to a password. The system further generates one or more challenges based on the extracted user information, and receives the user's response to the challenges. Subsequently, the system compares the user's response to the extracted user information, and authenticates the user.