Enhanced call-back authentication method and apparatus

Abstract: A method and apparatus for remotely accessing a host computer from a remote location. The invention permits a user to remotely change a telephone number that allows the host computer to dial the user's current location. A user performs this change only after he has been strongly authenticated using a distributed user authentication protocol in addition to a simple user ID and password. This allows the user to move between locations and access the host computer, while the call-back feature protects the host computer from unauthorized intrusion. Also, a second registered user who does not have call-back authority may gain access to the host computer through a user that has call-back authority. In this case the user with call-back authority gains entry into the host computer and causes it to call the second registered user, who then enters a user ID and password to gain entry to the host computer. The present invention may be implemented in the host computer or in an interface coupled between the host computer and its modem.

Description: BACKGROUND The present invention relates generally to methods for remotely accessing a host computer system, and more particularly, to methods that provide for remotely accessing a host computer system from a plurality of remote sites by a single user. To protect a host computer system from outside intruders using a dial-in modem attached thereto, the host computer system may require users to use a call-back procedure. A typical conventional call-back procedure works as follows. A remote user of the host computer system registers a remote telephone number with the system administrator. This remote telephone number is one where the remote computer is located. Once the user is at the remote location, and after he signs on, the user provides a user identification code and password. Then, the host computer system will call back to the user at the registered phone number for further processing. However, in the conventional procedure, a single user identification code permits the use of only one registered telephone number. If the user wants to use the host computer system from another location, he must register the new number ahead of time. For a user who frequently travels to different remote locations, this procedure does not permit him to switch telephone number easily and quickly. In addition, even if the telephone numbers of remote locations are known ahead of time, only one number can be registered at a time. Consequently, the existing procedure is too inflexible to be widely used. It permits a user to use the system from one remote location and from one registered phone number. For a user who moves around, he has no way to access the host computer system from various remote sites. Therefore it would he an advantage to have a remote access procedure that permits a remote user to move between remote locations and easily and quickly change the remote call-back telephone number to permit him to access the host computer system. EP-0262859 A1 discloses an adjunct processor for providing computer facility access protection via call transfer, comprising prompts to provide identification information, and initiation of a call back operation upon correct identification. Computer Technology Review, V, Fall 1985, No. 4, Los Angeles, CA, USA, pp25-31, G. Horback, "Callback Security Unit Protects Switched Data Communication System", describes a system wherein the location from where remote access to a system is made may be changed using appropriate access codes. US 4,801,787 discloses a complex challenge and answer authentication procedure for application in security systems relating to IC smart cards. SUMMARY OF THE INVENTION In order to provide for the above advantages, the present invention comprises a method and apparatus, as claimed in claims 1, 2 and 3 hereinafter, that provides for remote accessing of a host computer system from a remote location. The method comprising the following steps. A remote user uses a remotely located computer and an attached modem to connect to the host computer system by way of a dial-in modem connected thereto. The remote user logs in by entering a user ID and password when requested by the host computer system. After passing an authentication check by entering the correct user ID and password, the remote user requests a modification to his registered phone number for call-back. The host computer system sends challenging questions using a distributed user authentication protocol, and the remote user answers these challenging questions by providing correct answers, incorrect answers, or no answers in a predetermined manner. If the remote user passes the challenging questions posed by the distributed user authentication protocol, the host computer system requests the input of a new phone number that is stored in a file on the host computer system associated with the user ID of the remote user. The host computer system breaks the telephone connection and dials the new registered phone number of the remote user. The remote user again logs in and the host computer system checks his authentication code, and if the authentication code is correct, the telephone connection is complete and the remote user has access to the host computer system. Using the present procedure, a user can remotely call in, authenticate himself using a distributed user authentication protocol, and change the registered phone number as frequently as it needs to be changed, while the host computer system maintains security through the call-back mechanism. The present invention permits a user to remotely change the registered telephone number for himself such that the host computer system can dial-back to the current location of the user. A user may perform this change only after he has been strongly authenticated using the distributed user authentication protocol in addition to simple user identification and password mechanism. This permits the user to move around from one location to another and be able to access the host computer system, which uses the call-back feature to protect itself from unauthorized intrusion. The present invention also permits a first registered user to allow another authorized user to gain remote access to a host computer. After the first user gains access to the host computer using the authentication procedure, the first user asks the computer to call a phone number at a location of a second registered user that does not have call-back authority. The authentication procedure of the present invention may also be implemented in an interface disposed between a modem and a host computer. After a remote user passes the appropriate password checks, the interface calls back the user and connects the remote user (or the second user) to the host computer. This offers additional protection of the information stored on the host computer such that intruders cannot have direct access to any information that is stored in the host computer or in a remote location. The present invention is therefore more user friendly and more useful than the initially described conventional procedure. For a user who moves around, using the present procedure, he has the ability to access the host computer system from various remote sites. BRIEF DESCRIPTION OF THE DRAWINGS The various features and advantages of the present invention may be more readily understood with reference to the following detailed description taken in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: Fig. 1 shows the apparatus required to implement a procedure in accordance with the principles of the present invention; and Fig. 2 is a flow diagram illustrating one procedure in accordance with the principles of the present invention.. DETAILED DESCRIPTION Referring to Fig. 1, it shows the apparatus 10 used to implement a procedure in accordance with the principles of the present invention. The apparatus includes a host computer system 11, that has a dial-in modem 12 connected thereto. A user 13 is located at a remote location and has a computer 14, which may be a computer workstation or a terminal, for example. The computer 14 has a modem 15 connected thereto. The modem 15 and the dial-in modem 12 are connected by way of telephone lines 16, for example, or other conventional communications link. Referring to Fig. 2, it shows a flow diagram illustrating one procedure 20 in accordance with the principles of the present invention that provides for remote accessing of the host computer system 11 from a remote location. The procedure 20 comprises the following steps, which may also be referred to as a procedural algorithm. In step 21, a remote user 13 uses the computer 14 and attached modem 15 to connect to the host computer system 11 by way of the dial-in modem 12. In step 22, the remote user 13 enters a user ID and password when requested by the host computer system 11. In step 23, after passing this authentication check, the remote user 13 either requests modification to the registered phone number for call-back or proceeds to step 25. In step 24, the host computer system 11 sends challenging questions using a distributed user authentication protocol, and the remote user 13 must answer these challenges correctly, incorrectly, or no answer in a predetermined manner. In step 25, if the remote user 13 passes the challenges of the distributed user authentication protocol, the host computer system 11 requests a new phone number to be stored in a file on the host computer system 11 for the user ID of the remote user 13. In step 26, the host computer system 11 breaks the telephone connection and dials the new registered phone number of the remote user 13. In step 27, the remote user 13 logs in and the host computer system 11 checks the authentication code of the remote user 13, and if it is correct, the telephone connection is complete. The above-described procedure 20 has been implemented on a SUN computer workstation and has been demonstrated to work well. Call connections from outside the facility where the SUN workstation (host computer 11) is located have been established from various locations by different users. A user's registered phone number may be easily changed using this procedure. Attempted intrusion into the host computer 11 has not been successful. The authentication procedure 20 of the present invention may also be implemented in the form of an interface 30 (shown in Fig. 1 that is disposed between the modem 12 and the host computer 11. After a remote user 13 passes the appropriate password checks, the interface 30 causes the modem 12 to call back the remote user 13 and connects the remote remote user 13 to the host computer 11. This offers additional protection of the information stored on the host computer 11 such that intruders cannot have direct access to any information that is stored in the host computer 11 or at a remote location that is accessible by the host computer 11 via the interface 30. The authentication procedure of the present invention also permits a registered user 13 to allow a second registered user 13a to gain remote access to the host computer system 11. After passing the tests of the present authentication procedure, the registered user 13 asks the computer 11 (or interface 30) to call a phone number at a second remote location 17, such as a second remote modem 18 coupled to a second remote computer 19. This phone number may be at a location where the second authorized user 13a is located. The second user 13a desires to connect to the host computer 11, but is unable to because the user 13a is not registered for call-back authority. With reference to to Fig. 3, it shows a flow diagram illustrating this second procedure 40 in accordance with the principles of the present invention that provides for remote accessing of the host computer system 11 from a remote location by a second registered user 13a that does not have call-back authority. The second user 13a has a second computer 19 and a modem 18 connected thereto. The procedure 40 comprises the following steps. In step 41, a remote user 13 uses a computer 14 and attached modem 15 to connect to the host computer system 11 by way of a dial-in modem 12. In step 42, the remote user 13 enters a user ID and password when requested by the host computer system 11. In step 43, after passing this authentication check, the remote user 13 enters a phone number of a second remote user 13a for call-back. In step 44, the host computer system 11 sends challenging questions using a distributed user authentication protocol, and the remote user 13 must answer these challenges correctly, incorrectly, or no answer in a predetermined manner. In step 45, if the remote user 13 passes the challenges of the distributed user authentication protocol, the host computer system 11 breaks the telephone connection and dials the phone number of the second remote user 13a. In step 46, the second remote user 13a logs in and the host computer system 11 checks the authentication code of the second remote user 13a, and if it is correct, the telephone connection is complete. Thus there has been described a new and improved method that provides for remotely accessing a host computer system from a plurality of remote sites by a single user.

Claims: A method that provides for remote accessing of a host computer system (11) from a remote location (14), said method comprising the following steps: a remote user (13) uses a remotely located computer (14) having an attached modem (15) to connect to the host computer system (11) by way of a modem (12) connected thereto; the remote user (13) logs in by entering a user ID and password when requested by the host computer system (11); after passing an authentication check by entering the correct user ID and password, the remote user (13) requests a modification to his registered phone number for call-back; the host computer system (11) send challenging questions using a distributed user authentication protocol, and the remote user (13) answers these challenging questions by providing correct answers, incorrect answers, or no answers in a predetermined manner; if the remote user passes the challenging questions posed by the distributed user authentication protocol, the host computer system (11) requests the input of a new phone number which is then registered by storing it in a file on the host computer system (11) associated with the user ID of the remote user (13); the host computer system (11) breaks the telephone connection and dials the new registered phone number of the remote user (13); and the remote user logs in from the new registered phone number and the host computer system (11) repeats the authentication check on user ID and password, if the check is passed the telephone connection is complete and the remote user (13) has access to the host computer system (11). A method that provides for remote accessing of a host computer system (11) from a remote location (14), said method comprising the following steps: a first remote user (13) uses a remotely located computer (14) having an attached modem (15) to connect to the host computer system (11) by way of a modem (12) connected thereto; the first remote user (13) logs in by entering a user ID and password when requested by the host computer system (11); after passing an authentication check by entering the correct user ID and password, the first remote user (13) inputs a phone number of a second remote user (13a) for call-back; the host computer system (11) sends challenging questions using a distributed user authentication protocol, and the remote user (13) answers these challenging questions by providing correct answers, incorrect answers, or no answers in a predetermined manner; if the first remote user (13) passes the challenging questions posed by the distributed user authentication protocol, the host computer system (11) breaks the telephone connection and dials the phone number of the second remote user (13a); and the second remote user (13a) logs in from this phone number and the host computer system (11) checks the authentication code, and if the authentication code is correct, the telephone connection is complete and the second remote user (13a) has access to the host computer system (11). Apparatus (10) that provides for remote accessing of a host computer system (11) from a remote location, said apparatus comprising: a first modem (15) attached to a first remotely located computer (14); a second modem (12) for use by the host computer system (11); and an interface (30) coupled between the host computer (11) and the second modem (12), said apparatus (10) characterised by performing a procedure according to the method of claims 1 or 2.

Inventors: BATHRICK ERWIN W, KUNG KENNETH, MATTHEWS TODD E, BATHRICK, ERWIN W., KUNG, KENNETH, MATTHEWS, TODD E.
Applicants: HUGHES ELECTRONICS CORP, HUGHES ELECTRONICS CORPORATION
Application year: 1993
Main classification: G06F1
IPC codes: H04Q11, H04M3, G06F21