Abstract:
The present disclosure relates generally to the management of privileges associated with certain applications that are accessible by users of electronic equipment, such as, for example, networked computers, mobile wireless communications devices, and the like. In a broad aspect, a method for managing privileges associated with applications comprises: monitoring a plurality of electronic devices within a system; detecting a change in privileges associated with one or more applications resident on the plurality of electronic devices, wherein one or more privileges that are to be revoked are identified; and in response to a detection of the change in privileges, revoking the one or more privileges, such that each of the one or more applications resident on the plurality of electronic devices no longer has access to the one or more privileges.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 12/561,370, filed on Sep. 17, 2009, and issued to patent as U.S. Pat. No. 8,522,321, which is a continuation of U.S. patent application Ser. No. 11/169,302, filed on Jun. 29, 2005, and issued to patent as U.S. Pat. No. 7,614,082. The entire contents of U.S. patent application Ser. No. 12/561,370, and U.S. patent application Ser. No. 11/169,302 are hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to the management of privileges associated with certain applications that are accessible by users of electronic equipment, such as, for example, networked computers, mobile wireless communications devices, and the like. In particular, the disclosure is directed to systems and methods for managing privileges associated with particular applications and for revoking these privileges in a timely and robust manner. 
     RELATED ART 
     It is well known that certain electronic equipment, such as, for example, networked computers, mobile wireless communications devices, and the like, include applications resident on such equipment that may have access to certain privileges that enable the applications to perform various functions. Typically, a system administrator may use IT policy and application control to set the privileges associated with various applications present on the equipment that is subject to the administrator&#39;s control. Examples of privileges may include, for example, allowing an application to use inter-process communication (IPC), enabling the opening of internal and external connections, enabling the injection of browser filters, enabling Bluetooth™ functionality, enabling use of e-mail, enabling the use of personal information management (PIM) functionality, use of application program interface (API), etc. It is important for the system administrator be able to track which applications have access to which privileges, and to be able to revoke privileges on an as needed basis. 
     For example, if an application has access to a privilege, and the system administrator revokes that privilege, the application should immediately, or within a small window of time, be denied access to that privilege. In other words, the privilege should be revoked as soon as possible. Events that might trigger a revocation of privileges may include, for example, an application being loaded before the IT administrator/application control data is present on the device, an application is discovered to be a rogue application, or company policy changes, resulting in limiting the use or availability of certain applications and/or privileges associated therewith. 
     Regardless of the reason for privilege revocation, such revocation must be accomplished in a secure manner and in a manner that prevents possible work arounds by malicious applications or individuals. In general, according to current privilege revocation schemes, privilege checking is typically performed on the first access to a privilege. For example, applications communicate with IPC using the application registry. Once an application has a reference (e.g., pointer) to the application registry, it is difficult to take this reference away from the application. In another example, if an application has passed some if its privileges to another application using IPC, conventional systems can detect that the first application has access to IPC, but there is no way to detect that the other application has been passed the privilege(s). 
     Therefore, there remains a need for a system and method for effectively managing privileges associated with applications, and in particular, when privilege revocation is required, to revoke these privileges in a timely and robust manner. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
       These and other embodiments along with their attendant advantages are described herein with reference to the following drawings in which like reference numerals refer to like elements, and wherein: 
         FIG. 1  is a block diagram showing a computer network and communication system in which electronic devices running applications having access to associated privileges are used; 
         FIG. 2  is a block diagram of a wireless mobile communication device as an example of an electronic device running applications having access to associated privileges; 
         FIG. 3  is a flow diagram illustrating a method of revoking privileges according to an exemplary embodiment; 
         FIG. 4  is a flow diagram illustrating a method of revoking privileges according to another exemplary embodiment; and 
         FIG. 5  is a flow diagram illustrating yet another method of revoking privileges according to another exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     In view of the foregoing, we have now identified an efficient, accurate, robust and easy to implement system and method for managing privileges associated with particular applications and for revoking these privileges in a timely and reliable manner 
     According to an exemplary embodiment an application having privileges that are to be revoked may be shut down. When this application is restarted, access to revoked privileges will be denied. In order to keep track of which applications need to be shut down and reset, the system must keep track of which applications have accessed which privileges. To enable monitoring of the privileges accessed by applications, each time an application uses a privilege, the system records the application identifier and which privilege has been accessed. This may be done in any of a number of conventional methods, such as, for example, a data table listing the application identifier and corresponding accessed privilege(s) associated with the application identifier. When the system administrator, or any other authority, institutes a change in privileges, the system accesses the record of which applications have accessed which privileges. A comparison of accessed privileges with the privileges to be revoked is performed. Each application that has accessed a privilege that is to be revoked is identified by the system and then shut down. When the application is restarted, the application will not have access to any of the revoked privileges. 
     In another embodiment, a device reset may be performed. By resetting a device, the system is brought to a known state. According to this embodiment, a system administrator, or any other authority, specifies that a device must be reset when a new policy that revokes (or changes) privileges is instituted. A device reset may be instituted at any time the administrator or authority deems it necessary to do so. For example, a device reset may be done whenever a new policy that includes privilege revocation is instituted. However, this may result in numerous unnecessary device reset events that are potentially inconvenient to the user and may interfere with use of the device. Alternatively, the system may keep track of which devices include which applications, and use this information to determine a less intrusive device reset schedule. For example, resetting only those devices having applications that may potentially be affected by the policy change. 
     In yet another advantageous embodiment, aspects of previously described embodiments are combined to provide effective privilege management and revocation. According to this exemplary embodiment, the system administrator or other authority has no actual control over when a device is reset. The administrator merely manages the privileges of the system and particular applications. The device itself is responsible for resetting when necessary. In this embodiment, the device keeps track of which applications get access to which privileges. When policies or application control changes, the system detects which privileges have been revoked for which applications. This can be accomplished by simply comparing the old set of privileges with the new set of privileges. For each revoked privilege for a given application, the system determines if the application has ever accessed that privilege in the past. As noted above, the system has been keeping track of these since the system was first started up. If an application has accessed a privilege that is now revoked at any time in the past, the device is reset. For some privileges (e.g., IPC), it still cannot be determined whether a privilege has been used as a result of being passed from another application. To overcome the potential for missing a revocation of privileges when applications pass privileges between themselves, if, for example, IPC (or any other privilege that is able to be passed between applications) is revoked from any application, regardless of if the system has detected that the application has accessed the privilege, the device must be reset. This reset will bring the device back to a known state. Device reset will only be done when necessary, thus limiting the number of resets and solving the problem associated with privileges that have been passed between applications. 
     Each of these embodiments is useful in a variety of privilege management environments ranging from a low-level low-priority where a modest level of privilege revocation security is needed, resulting in a less robust system, to a highly important ultra-robust environment where user inconvenience is secondary to the need for absolute certainty of privilege revocation. 
       FIG. 1  is a block diagram showing a computer network and communication system in which electronic devices running applications having access to associated privileges are uses. The computer network  18  includes, for example, various networked computers  28  and, optionally, a message server  26 , all linked via a Local Area Network (LAN)  30 . The communication system includes a Wide Area Network (WAN)  12  coupled to a computer system  14 , a wireless network gateway  16  and the LAN  30  of the computer network  18 . The wireless network gateway  16  is also connected to a wireless communication network  20  in which a wireless mobile communication device  22  (hereinafter “mobile device”), is configured to operate. The entire system  10  is typically managed by, among others, a system administrator or like authority  32 . 
     The computer system  14  may be a desktop or laptop personal computer that is configured to communicate with the WAN  12  or any other suitable network, such as, for example, the Internet. Personal computers, such as the computer system  14 , typically access the Internet via an Internet Service Provider (ISP), Application Service Provider (ASP), or the like. 
     The LAN  30  is an example of a typical working computer network environment, in which multiple computers  28  are connected in a network. The computer network  18  is typically located behind a security firewall  24 . Within the LAN  30 , a message server  26 , operating on a computer behind the firewall  24  may act as the primary interface for the owner of the computer network  18  to exchange messages both within the LAN  30  and with other external messaging clients via the WAN  12 . Known message servers include, for example, Microsoft Outlook™, Lotus Notes™, Yahoo!™, Messenger, AOL Instant Messenger, or any other client-server or peer-to-peer, or similar messaging clients with various architectures. Messages received by the message server  26  are distributed to mailboxes for user accounts addressed in the received messages, and are then accessed by a user through a messaging client operating on a computer system  28 . The foregoing is merely an exemplary description illustrating a client-server architecture, and in no way implies that such architecture is necessary, as other suitable architectures known to those skilled in the art may be used. 
     Although only a message server  26  is shown in the LAN  30 , those skilled in the art will appreciate that a LAN may include other types of servers supporting resources that are shared between the networked computer systems  28 , and that the message server  26  may also provide additional functionality, such as dynamic database storage for data such as, but not limited to, calendars, to-do lists, task lists, e-mail and documentation. The message server  26  and electronic messaging are described for illustrative purposes only. Systems and methods for managing and revoking privileges are applicable to a wide range of electronic devices, and are in no way limited to electronic devices with messaging capabilities. 
     The wireless gateway  16  provides an interface to a wireless network  20 , through which messages may be exchanged with a mobile device  22 . Such functions as addressing of the mobile device  22 , encoding or otherwise transforming messages for wireless transmission, and any other interface functions are performed by the wireless gateway  16 . The wireless gateway  16  may be configured to operate with more than one wireless network  20 , in which case the wireless gateway  16  also determines a most likely network for locating a given mobile device  22  and possibly track mobile devices as users roam between countries or networks. 
     The mobile device  22  is, for example, a data communication device, a voice communication device, a dual-mode communication device such as many modern cellular telephones having both data and voice communications functionality, a multiple-mode device capable of voice, data and other types of communications, a personal digital assistant (PDA) enabled for wireless communications, or a laptop or desktop computer system with a wireless modem. 
     Any computer system with access to the WAN  12  may exchange messages with the mobile device  22  through the wireless network gateway  16 . Alternatively, private wireless network gateways such as wireless Virtual Private Network (VPN) routers could be implemented to provide a private interface to a wireless network. A wireless VPN router implemented in the LAN  30  provides a private interface from the LAN  30  to one or more mobile devices such as  22  through the wireless network  20 . A private interface to a mobile device  22  may also effectively be extended to entities outside the LAN  30  by providing a message forwarding or redirection system that operates with the message server  26 . Such a message redirection system is disclosed in U.S. Pat. No. 6,219,694, which is hereby incorporated into this application by reference. In this type of system, incoming messages received by the message server  26  and addressed to a user of a mobile device  22  are sent through the wireless network interface, either a wireless VPN router, the wireless gateway  16 , or another interface, for example, to the wireless network  20  and to the user&#39;s mobile device  22 . Another alternate interface to a user&#39;s mailbox on a message server  26  may be a Wireless Application Protocol (WAR) gateway. Through a WAP gateway, a list of messages in a user&#39;s mailbox on the message server  26 , and possibly each message or a portion of each message, may be sent to the mobile device  22 . A wireless network  20  normally delivers messages to and from communication devices such as the mobile device  22  via RF transmissions between base stations and devices. The wireless network  20  may, for example, be a data-centric wireless network, a voice-centric wireless network, or a dual-mode network that can support both voice and data communications over the same infrastructure. Recently developed networks include Code Division Multiple Access (CDMA) networks and General Packet Radio Service (GPRS) networks. So-called third-generation (3G) networks like Enhanced Data rates for Global Evolution (EDGE) and Universal Mobile Telecommunications Systems (UMTS) are currently under development. Older data-centric networks include, but are not limited to, the Mobitex™ Radio Network (“Mobitex”), and the DataTAC™ Radio Network (“DataTAC”). Voice-centric data networks such as Personal Communication System (PCS) networks, including Global System for Mobile Communications (GSM) and Time Division Multiple Access (TDMA) systems, have been available in North America and world-wide for several years. 
       FIG. 2  is a block diagram of an exemplary wireless mobile communication device as an example of an electronic device. However, it should be understood that the systems and methods disclosed herein may be used with many different types of devices, such as personal digital assistants (PDAs), desktop computers, or the like. 
     The mobile device  500  is preferably a two-way communication device having at least voice and data communication capabilities. The mobile device  500  preferably has the capability to communicate with other computer systems on the Internet. Depending on the functionality provided by the mobile device, the mobile device may be referred to as a data messaging device, a two-way pager, a cellular telephone with data messaging capabilities, a wireless Internet appliance, or a data communication device (with or without telephony capabilities). As mentioned above, such devices are referred to generally herein as mobile devices. 
     The mobile device  500  includes a transceiver  511 , a microprocessor  538 , a display  522 , non-volatile memory  524 , random access memory (RAM)  526 , auxiliary input/output (I/O) devices  528 , a serial port  530 , a keyboard  532 , a speaker  534 , a microphone  536 , a short-range wireless communications sub-system  540 , and may also include other device sub-systems  542 . The transceiver  511  preferably includes transmit and receive antennas  516 ,  518 , a receiver (Rx)  512 , a transmitter (Tx)  514 , one or more local oscillators (LOs)  513 , and a digital signal processor (DSP)  520 . Within the non-volatile memory  524 , the mobile device  500  includes a plurality of software modules  524 A- 524 N that can be executed by the microprocessor  538  (and/or the DSP  520 ), including a voice communication module  524 A, a data communication module  524 B, and a plurality of other operational modules  524 N for carrying out a plurality of other functions. 
     The mobile device  500  is preferably a two-way communication device having voice and data communication capabilities. Thus, for example, the mobile device  500  may communicate over a voice network, such as any of the analog or digital cellular networks, and may also communicate over a data network. The voice and data networks are depicted in  FIG. 2  by the communication tower  519 . These voice and data networks may be separate communication networks using separate infrastructure, such as base stations, network controllers, etc., or they may be integrated into a single wireless network. References to the network  519  should therefore be interpreted as encompassing both a single voice and data network and separate networks. 
     The communication subsystem  511  is used to communicate with the network  519 . The DSP  520  is used to send and receive communication signals to and from the transmitter  514  and receiver  512 , and also exchange control information with the transmitter  514  and receiver  512 . If the voice and data communications occur at a single frequency, or closely-spaced set of frequencies, then a single LO  513  may be used in conjunction with the transmitter  514  and receiver  512 . Alternatively, if different frequencies are utilized for voice communications versus data communications or the mobile device  500  is enabled for communications on more than one network  519 , then a plurality of LOs  513  can be used to generate frequencies corresponding to those used in the network  519 . Although two antennas  516 ,  518  are depicted in  FIG. 2 , the mobile device  500  could be used with a single antenna structure. Information, which includes both voice and data information, is communicated to and from the communication module  511  via a link between the DSP  520  and the microprocessor  538 . 
     The detailed design of the communication subsystem  511 , such as frequency band, component selection, power level, etc., is dependent upon the communication network  519  in which the mobile device  500  is intended to operate. For example, a mobile device  500  intended to operate in a North American market may include a communication subsystem  511  designed to operate with the Mobitex or DataTAC mobile data communication networks and also designed to operate with any of a variety of voice communication networks, such as AMPS, TDMA, CDMA, PCS, etc., whereas a mobile device  500  intended for use in Europe may be configured to operate with the GPRS data communication network and the GSM voice communication network. Other types of data and voice networks, both separate and integrated, may also be utilized with the mobile device  500 . 
     Communication network access requirements for the mobile device  500  also vary depending upon the type of network  519 . For example, in the Mobitex and DataTAC data networks, mobile devices are registered on the network using a unique identification number associated with each device. In GPRS data networks, however, network access is associated with a subscriber or user of the mobile device  500 . A GPRS device typically requires a subscriber identity module (“SIM”), which is required in order to operate the mobile device  500  on a GPRS network. Local or non-network communication functions (if any) may be operable, without the SIM, but the mobile device  500  is unable to carry out functions involving communications over the network  519 , other than any legally required operations, such as ‘911’ emergency calling. 
     After any required network registration or activation procedures have been completed, the mobile device  500  is able to send and receive communication signals, preferably including both voice and data signals, over the network  519 . Signals received by the antenna  516  from the communication network  519  are routed to the receiver  512 , which provides for signal amplification, frequency down conversion, filtering, channel selection, etc., and may also provide analog to digital conversion. Analog to digital conversion of the received signal allows more complex communication functions, such as digital demodulation and decoding, to be performed using the DSP  520 . In a similar manner, signals to be transmitted to the network  519  are processed, including modulation and encoding, for example, by the DSP  520  and are then provided to the transmitter  514  for digital to analog conversion, frequency up conversion, filtering, amplification and transmission to the communication network  519  via the antenna  518 . Although a single transceiver  511  is shown for both voice and data communications, in alternative embodiments, the mobile device  500  may include multiple distinct transceivers, such as a first transceiver for transmitting and receiving voice signals, and a second transceiver for transmitting and receiving data signals, or a first transceiver configured to operate within a first frequency band, and a second transceiver configured to operate within a second frequency band. 
     In addition to processing the communication signals, the DSP  520  also provides for receiver and transmitter control. For example, the gain levels applied to communication signals in the receiver  512  and transmitter  514  may be adaptively controlled through automatic gain control algorithms implemented in the DSP  520 . Other transceiver control algorithms could also be implemented in the DSP  520  in order to provide more sophisticated control of the transceiver  511 . 
     The microprocessor  538  preferably manages and controls the overall operation of the mobile device  500 . Many types of microprocessors or microcontrollers could be used here, or, alternatively, a single DSP  520  could be used to carry out the functions of the microprocessor  538 . Low-level communication functions, including at least data and voice communications, are performed through the DSP  520  in the transceiver  511 . High-level communication applications, including the voice communication application  524 A, and the data communication application  524 B are stored in the non-volatile memory  524  for execution by the microprocessor  538 . For example, the voice communication module  524 A may provide a high-level user interface operable to transmit and receive voice calls between the mobile device  500  and a plurality of other voice devices via the network  519 . Similarly, the data communication module  524 B may provide a high-level user interface operable for sending and receiving data, such as e-mail messages, files, organizer information, short text messages, etc., between the mobile device  500  and a plurality of other data devices via the network  519 . 
     The microprocessor  538  also interacts with other device subsystems, such as the display  522 , RAM  526 , auxiliary I/O devices  528 , serial port  530 , keyboard  532 , speaker  534 , microphone  536 , a short-range communications subsystem  540  and any other device subsystems generally designated as  542 . For example, the modules  524 A-N are executed by the microprocessor  538  and may provide a high-level interface between a user of the mobile device and the mobile device. This interface typically includes a graphical component provided through the display  522 , and an input/output component provided through the auxiliary I/O devices  528 , keyboard  532 , speaker  534 , or microphone  536 . Additionally, the microprocessor  538  is capable of running a variety of applications that may be present in the device non-volatile memory  524 , including applications that have access to various privileges, as will be described in more detail herein. 
     Some of the subsystems shown in  FIG. 2  perform communication-related functions, whereas other subsystems may provide “resident” or on-device functions. Notably, some subsystems, such as keyboard  532  and display  522  may be used for both communication-related functions, such as entering a text message for transmission over a data communication network, and device-resident functions such as a calculator or task list or other PDA type functions. 
     Operating system software used by the microprocessor  538  is preferably stored in a persistent store such as the non-volatile memory  524 . In addition to the operating system and communication modules  524 A-N, the non-volatile memory  524  may include a file system for storing data. The non-volatile memory  524  may also include data stores for owner information and owner control information. The operating system, specific device applications or modules, or parts thereof, may be temporarily loaded into a volatile store, such as RAM  526  for faster operation. Moreover, received communication signals may also be temporarily stored to RAM  526 , before permanently writing them to a file system located in the non-volatile memory  524 . The non-volatile memory  524  may be implemented, for example, with Flash memory, non-volatile RAM, or battery backed-up RAM. 
     An exemplary application module  524 N that may be loaded onto the mobile device  500  is a PIM application providing PDA functionality, such as calendar events, appointments, and task items. This module  524 N may also interact with the voice communication module  524 A for managing phone calls, voice mails, etc., and may also interact with the data communication module  524 B for managing e-mail communications and other data transmissions. Alternatively, all of the functionality of the voice communication module  524 A and the data communication module  524 B may be integrated into the PIM module. 
     The non-volatile memory  524  preferably provides a file system to facilitate storage of PIM data items on the device. The PIM application preferably includes the ability to send and receive data items, either by itself, or in conjunction with the voice and data communication modules  524 A,  524 B, via the wireless network  519 . The PIM data items are preferably seamlessly integrated, synchronized and updated, via the wireless network  519 , with a corresponding set of data items stored or associated with a host computer system, thereby creating a mirrored system for data items associated with a particular user. 
     The mobile device  500  is manually synchronized with a host system by placing the mobile device  500  in an interface cradle, which couples the serial port  530  of the mobile device  500  to a serial port of the host system. The serial port  530  may also be used to insert owner information and owner control information onto the mobile device  500  and to download other application modules  524 N for installation on the mobile device  500 . This wired download path may further be used to load an encryption key onto the mobile device  500  for use in secure communications, which is a more secure method than exchanging encryption information via the wireless network  519 . 
     Owner information, owner control information and additional application modules  524 N may be loaded onto the mobile device  500  through the network  519 , through an auxiliary I/O subsystem  528 , through the short-range communications subsystem  540 , or through any other suitable subsystem  542 , and installed by a user in the non-volatile memory  524  or RAM  526 . Such flexibility in application installation increases the functionality of the mobile device  500  and may provide enhanced on-device functions, communication-related functions, or both. For example, secure communication applications may enable electronic commerce functions and other such financial transactions to be performed using the mobile device  500 . 
     When the mobile device  500  is operating in a data communication mode, a received signal, such as a text message or a web page download, will be processed by the transceiver  511  and provided to the microprocessor  538 , which preferably further processes the received signal for output to the display  522 , or, alternatively, to an auxiliary I/O device  528 . Owner information, owner control information, commands or requests related to owner information or owner control information, and software applications received by the transceiver  511  are processed as described above. A user of mobile device  500  may also compose data items, such as email messages, using the keyboard  532 , which is preferably a complete alphanumeric keyboard laid out in the QWERTY style, although other styles of complete alphanumeric keyboards such as the known DVORAK style may also be used. User input to the mobile device  500  is further enhanced with the plurality of auxiliary I/O devices  528 , which may include a thumbwheel input device, a touchpad, a variety of switches, a rocker input switch, etc. The composed data items input by the user are then transmitted over the communication network  519  via the transceiver  511 . 
     When the mobile device  500  is operating in a voice communication mode, the overall operation of the mobile device  500  is substantially similar to the data mode, except that received signals are output to the speaker  534  and voice signals for transmission are generated by a microphone  536 . In addition, the secure messaging techniques described above might not necessarily be applied to voice communications. Alternative voice or audio I/O devices, such as a voice message recording subsystem, may also be implemented on the mobile device  500 . Although voice or audio signal output is accomplished through the speaker  534 , the display  522  may also be used to provide an indication of the identity of a calling party, the duration of a voice call, or other voice call related information. For example, the microprocessor  538 , in conjunction with the voice communication module  524 A and the operating system software, may detect the caller identification information of an incoming voice call and display it on the display  522 . 
     A short-range communications subsystem  540  is also included in the mobile device  500 . For example, the subsystem  540  may include an infrared device and associated circuits and components, or a Bluetooth or 802.11 short-range wireless communication module to provide for communication with similarly-enabled systems and devices. Thus, owner information insertion, owner control information insertion, and application loading operations as described above may be enabled on the mobile device  500  via the serial port  530  or other short-range communications subsystem  540 . 
       FIG. 2  represents a specific example of an electronic device in which owner control systems and methods described herein may be implemented. Implementation of such systems and methods in other electronic devices having further, fewer, or different components than those shown in  FIG. 2  would occur to one skilled in the art to which this application pertains and are therefore considered to be within the scope of the present application. 
       FIG. 3  is a flow diagram illustrating a method of revoking privileges according to an exemplary embodiment. In this example, an application having privileges that are to be revoked may be shut down. When the application is restarted, access to revoked privileges will be denied. In order to keep track of which applications need to be shut down and reset, the system must keep track of which applications have access to which privileges. To accomplish this, for example, the system monitors and detects use of privileges by applications  300 . The system may record an application identifier associated with a particular application and which privilege has been accessed by the application  302 . This may be accomplished in any number of conventional methods that are readily apparent to those skilled in the art. For example, a data table listing the application identifier and having pointers directed to privilege(s) accessed by the application or associated with the application identifier. The system then continues to monitor the system for any change, for example, a change in IT policy, that might result in a revocation of privileges  304 . So long as no such change is detected in decision block  304 , the system continues to monitor and keep track of applications and associated privileges. 
     Upon a detection of a change that would result in revocation of privileges being accessed by applications in the system by the decision block  304 , such as, for example, a change in IT policy, a comparison of the recorded data relating to the accessed privileges with a listing of the new privileges is performed  306 . For example, the application identifiers and associated accessed privileges recorded in step  302  are compared to the new privilege list, or to a list of revoked privileges  306 . The changes discussed herein are typically instituted and administered by a system administrator or other authority who has responsibility for operation and management of the system. 
     As a result of the comparison  306 , each application that has accessed a privilege(s) to be revoked is identified  308  by the system. Upon identification of these applications, the system implements a shut down of these identified applications  310 . When these applications are restarted  312 , the applications will not have access to any of the revoked privileges. The system will continue to monitor and detect the accessing of privileges and associated applications as described above. 
     In another embodiment, as illustrated in the flow diagram of  FIG. 4 , a device reset may be performed. According to this example, all devices in the system are monitored  400 . A system administrator or other authority specifies, for example, that whenever there is a change in system policy that requires revocation or changes in privileges  402 , all devices in the system must be reset  404 . Resetting the devices brings the system to a known state, i.e., a state in which the system knows which applications have access to which privileges throughout the system. Upon restarting these applications  406  after the device reset  404 , the applications will no longer have access to any of the revoked privileges. According to this example, a device reset may be instituted any time the system administrator or authority deems it necessary to do so. For example, a device reset may be done whenever a new policy that includes privilege revocation is instituted. As a result, this solution may invoke numerous (potentially unnecessary) device reset events that may be intrusive and inconvenient for the users. However, this embodiment provides very robust and timely privilege revocation, and is thus suitable to highly secure systems where privilege management is more important than user convenience. 
     Turning now to  FIG. 5 , another advantageous embodiment implementing features of both embodiments described above with respect to  FIGS. 3 and 4  is illustrated. According to this example, aspects of the previously described embodiments are combined to provide highly effective and timely privilege management and revocation. In this example, the system administrator or authority has no actual control over when a device is reset. The administrator or authority merely manages the privileges of the system and of particular applications. The device itself is responsible for resetting as needed. 
     In this example, the device monitors which applications of the device have access to which privileges  600 , and a log of privileges for the device is kept  602 . The device monitors whether policies or application control changes are made in the system  604 . If there is no change detected  604 , the device continues to monitor applications and keep a log of privileges for the device  600 ,  602 . If a change in policy or application control is detected in step  604 , the system determines which privileges have been revoked for which applications by comparing the old set of privileges in the log with the new set of privileges received from the system administrator  606 . The device then determines if any revoked privileges are present on the device  608 . If revoked privileges are detected, e.g., if an application has accessed a privilege at any time in the past that has now been revoked, the device will reset  610 . As described above, resetting the device brings the system to a known state in which all applications and privileges are known. After the device is reset  610 , it is restarted  612 . Upon restart  612 , the device applications will have access to the correct privileges. Advantageously, if no revoked privileges are detected in step  608 , the device performs another check to ensure that no privileges that have been passed between application have been missed. As explained above, for some privileges, e.g., IPC, it cannot be determined whether a privilege has been used as a result of being passed from another application. To overcome the potential for missing revocation of privileges when applications pass privileges between themselves, the system checks for privileges that are able to be passed between applications (e.g., IPC)  614 . If a privilege that is able to be passed between applications is revoked from any application, regardless of if the system has detected that the application has accessed the privilege  614 , the device must be reset  610  to bring the system to a known state. After resetting, the device is restarted  612 , and will now have the only have access to the correct privileges. In this manner, device reset will only be performed when necessary, thus limiting the number of resets and solving the problem associated with privileges that go undetected due to their ability to be passed between applications. 
     While this disclosure describes specific exemplary embodiments, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the exemplary embodiments described herein, are intended to be illustrative, not limiting. Various changes may be made without departing from the true spirit and full scope of the invention, as defined in the following claims.