JTAG fuse vulnerability determination and protection using a trusted execution environment

None.

Not applicable.

Not applicable.

Network capable electronic devices are becoming increasingly prevalent in our daily lives. Additionally, more and more electronic devices that did not have network capabilities are getting network capable. With the rapid development and popularization of network capable electronic devices, a wide variety of increasingly sophisticated techniques are being deployed by attackers to take control of electronic devices and obtain confidential information, for example personal and payment data. The development of online application stores also helps cause rapid development, distribution and proliferation of malware applications across the network. The behavior of uncontrollable electronic device or leak of confidential user information and their impact on the user experience may have implications for user satisfaction with the electronic device and/or the network service provider.

In an embodiment, a method of configuring a trusted security zone into a portable electronic device is disclosed. The method comprises executing instructions on a processor of the portable electronic device that determine the state of a JTAG (JTAG) port of the portable electronic device, if the JTAG port is determined to be enabled, executing instructions on the processor preventing configuration of the trusted security zone into the portable electronic device, and if the JTAG port is determined to be disabled, configuring the trusted security zone into the portable electronic device, wherein the trusted security zone provides hardware assisted trust, whereby a vulnerability to hacking the trusted security zone via an enabled JTAG port is reduced.

In an embodiment, a method of protecting an electronic device from a hacking attack that exploits a JTAG (JTAG) port of the electronic device that has not been disabled is disclosed. The method comprises executing instructions on a processor of the electronic device that determine the state of a JTAG port of the electronic device, if the JTAG port is determined to be enabled, executing instructions on the processor of the electronic device to detect a physical connection to the JTAG port, if a physical connection to the JTAG port is detected, executing instructions on the processor preventing execution of trusted applications, and if the JTAG port is determined to be enabled, executing instructions on the processor preventing execution of software that reads from the JTAG port, whereby a vulnerability of the electronic device to a hacking attack that exploits an enabled JTAG port is reduced.

In an embodiment, a method of thwarting a hacking attack on a mobile phone via an enabled JTAG (JTAG) port of the mobile phone is disclosed. The method comprises executing instructions on a processor of the mobile phone that detect the state of the JTAG port as one of enabled or disabled and when the JTAG port is determined to be enabled, taking a first action to reduce vulnerability to hacking attacks via the enabled JTAG port.

These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims.

For a more complete understanding of the present disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.

FIG. 1 is an illustration of a communication system according to an embodiment of the disclosure.

FIG. 2 is a flow chart illustrating a method according to an embodiment of the disclosure.

FIG. 3 is a flow chart illustrating another method according to an embodiment of the disclosure.

FIG. 4 is an illustration of a mobile communication device according to an embodiment of the disclosure.

FIG. 5 is a block diagram of a mobile communication device according to an embodiment of the disclosure.

FIG. 6A is a block diagram of a software architecture of a mobile communication device according to an embodiment of the disclosure.

FIG. 6B is a block diagram of another software architecture of a mobile communication device according to an embodiment of the disclosure.

FIG. 7 is a block diagram of a computer system according to an embodiment of the disclosure.

It should be understood at the outset that although illustrative implementations of one or more embodiments are illustrated below, the disclosed systems and methods may be implemented using any number of techniques, whether currently known or not yet in existence. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, but may be modified within the scope of the appended claims along with their full scope of equivalents.

Problems may be caused by electronic devices that interfere with the proper operation of electronic devices or the coupled networks—for example the ability of electronic devices to transmit or receive confidential information. The problems may result from malware that infected the electronic devices through the coupled network. For example, malware that infect an electronic device via Internet may try to control the electronic device or steal personal or payment information from the electronic device. “Backdoor” malware that infected an electronic device may give attackers full access via joint test action group (JTAG) ports to users' devices. Because device manufacturers may leave JTAG ports enabled intentionally or accidentally, there is little the service provider or user can do to assure the reliability of the electronic devices with enabled JTAG ports. The present disclosure teaches a method for proactively examining the status of a JTAG port of an electronic device and taking further action to assure the reliability of the electronic device under different circumstances.

For example, instructions may be executed by the processor of an electronic device to determine the status of a JTAG port of the electronic device and take corresponding proactive action. When the JTAG port is determined to be disabled, a trusted security zone is also configured into the electronic device. A JTAG port inspected certificate is also generated for the electronic device with the disabled JTAG port. Furthermore, the JTAG port inspected certificate is stored into secure memory in the trusted security zone of the electronic device. When the JTAG port is determined to be enabled, a trusted security zone is prevented from configuring into the electronic device. Software that reads from the JTAG port is prevented from executing on the electronic device with an enabled JTAG port. If a physical connection is detected to the JTAG port after the JTAG port is determined to be enabled, execution of trusted applications on the electronic device will be prevented. In an embodiment, one or more untrusted applications may be prevented from executing on the electronic device after the JTAG port is determined to be enabled.

A trusted security zone provides chipsets with a hardware root of trust, a secure execution environment for applications, and secure access to peripherals. A hardware root of trust means the chipset should only execute programs intended by the device manufacturer or vendor and resists software and physical attacks, and therefore remains trusted to provide the intended level of security. The chipset architecture is designed to promote a programmable environment that allows the confidentiality and integrity of assets to be protected from specific attacks. Trusted security zone capabilities are becoming features in both wireless and fixed hardware architecture designs. Providing the trusted security zone in the main mobile device chipset and protecting the hardware root of trust removes the need for separate secure hardware to authenticate the device or user. To ensure the integrity of the applications requiring trusted data, such as a mobile financial services application, the trusted security zone also provides the secure execution environment where only trusted applications can operate, safe from attacks. Security is further promoted by restricting access of non-trusted applications to peripherals, such as data inputs and data outputs, while a trusted application is running in the secure execution environment. In an embodiment, the trusted security zone may be conceptualized as hardware assisted security.

A complete trusted execution environment (TEE) may be implemented through the use of the trusted security zone hardware and software architecture. The trusted execution environment is an execution environment that is parallel to the execution environment of the main mobile device operating system. The trusted execution environment and/or the trusted security zone may provide a base layer of functionality and/or utilities for use of applications that may execute in the trusted security zone. For example, in an embodiment, trust tokens may be generated by the base layer of functionality and/or utilities of the trusted execution environment and/or trusted security zone for use in trusted end-to-end communication links to document a continuity of trust of the communications. Through standardization of application programming interfaces (APIs), the trusted execution environment becomes a place to which scalable deployment of secure services can be targeted. A device which has a chipset that has a trusted execution environment on it may exist in a trusted services environment, where devices in the trusted services environment are trusted and protected against attacks. The trusted execution environment can be implemented on mobile phones and tablets as well as extending to other trusted devices such as personal computers, servers, sensors, medical devices, point-of-sale terminals, industrial automation, handheld terminals, automotive, etc.

The trusted security zone is implemented by partitioning all of the hardware and software resources of the mobile device into two partitions: a secure partition and a normal partition. The secure partition may be implemented by a first physical processor, and the normal partition may be implemented by a second physical processor. Alternatively, the secure partition may be implemented by a first virtual processor, and the normal partition may be implemented by a second virtual processor. Placing sensitive resources in the secure partition can protect against possible attacks on those resources. For example, resources such as trusted software applications may run in the secure partition and have access to hardware peripherals such as a touchscreen or a secure location in memory. Less secure peripherals such as wireless radios may be disabled completely while the secure partition is being accessed, while other peripherals may only be accessed from the secure partition. While the secure partition is being accessed through the trusted execution environment, the main mobile operating system in the normal partition is suspended, and applications in the normal partition are prevented from accessing the secure peripherals and data. This prevents corrupted applications or malware applications from breaking the trust of the device.

The trusted security zone is implemented by partitioning the hardware and software resources to exist in a secure subsystem which is not accessible to components outside the secure subsystem. The trusted security zone is built into the processor architecture at the time of manufacture through hardware logic present in the trusted security zone which enables a perimeter boundary between the secure partition and the normal partition. The trusted security zone may only be manipulated by those with the proper credential and, in an embodiment, may not be added to the chip after it is manufactured. Software architecture to support the secure partition may be provided through a dedicated secure kernel running trusted applications. Trusted applications are independent secure applications which can be accessed by normal applications through an application programming interface in the Trusted Execution Environment on a chipset that utilizes the trusted security zone.

In an embodiment, the normal partition applications run on a first virtual processor, and the secure partition applications run on a second virtual processor. Both virtual processors may run on a single physical processor, executing in a time-sliced fashion, removing the need for a dedicated physical security processor. Time-sliced execution comprises switching contexts between the two virtual processors to share processor resources based on tightly controlled mechanisms such as secure software instructions or hardware exceptions. The context of the currently running virtual processor is saved, the context of the virtual processor being switched to is restored, and processing is restarted in the restored virtual processor. Time-sliced execution protects the trusted security zone by stopping the execution of the normal partition while the secure partition is executing.

The two virtual processors context switch via a processor mode called monitor mode when changing the currently running virtual processor. The mechanisms by which the processor can enter monitor mode from the normal partition are tightly controlled. The entry to monitor mode can be triggered by software executing a dedicated instruction, the Secure Monitor Call (SMC) instruction, or by a subset of the hardware exception mechanisms such as hardware interrupts, which can be configured to cause the processor to switch into monitor mode. The software that executes within monitor mode then saves the context of the running virtual processor and switches to the secure virtual processor.

The trusted security zone runs a separate operating system that is not accessible to the device users. For security purposes, the trusted security zone is not open to users for installing applications, which means users do not have access to install applications in the trusted security zone. This prevents corrupted applications or malware applications from executing powerful instructions reserved to the trusted security zone and thus preserves the trust of the device. The security of the system is achieved at least in part by partitioning the hardware and software resources of the mobile phone so they exist in one of two partitions, the secure partition for the security subsystem and the normal partition for everything else. Placing the trusted security zone in the secure partition and restricting access from the normal partition protects against software and basic hardware attacks. Hardware logic ensures that no secure partition resources can be accessed by the normal partition components or applications. A dedicated secure partition operating system runs in a virtual processor separate from the normal partition operating system that likewise executes in its own virtual processor. Users may install applications on the mobile device which may execute in the normal partition operating system described above. The trusted security zone runs a separate operating system for the secure partition that is installed by the mobile device manufacturer or vendor, and users are not able to install new applications in or alter the contents of the trusted security zone.

Turning now to FIG. 1 , a communication system 100 is described. In an embodiment, the system 100 comprises a plurality of electronic devices 102 . The electronic device 102 may comprise one or more processors 104 , one or more JTAG (JTAG) ports 106 , an operating system 108 , and a memory 126 . In an embodiment, the device 102 may have access to a network 118 . A server computer 114 is coupled to the network 118 , for example a server 114 operated by a network service provider. The network 118 may also be accessible to an attacker computer 116 . The network 118 may comprise any combination of private and public networks.

It is understood that the system 100 may comprise any number of servers 114 and any number of attackers 116 . The electronic device 102 and attacker 116 may be any of a computer, a tablet computer, a mobile phone, a personal digital assistant (PDA), a media player, a game console, an Internet digital media streaming device, or another network/communications capable device. Computers are discussed in more detail hereinafter. The electronic device 102 and the attacker 116 may access the network 118 through wired or wireless access network. The wired access network may be abstracted in different ways and may comprise cable modems and Ethernet routers, switches, or hubs. The wireless access network may also be abstracted in different ways and may comprise wireless access points, cable modems, Ethernet or wireless routers, switches, or hubs, servers and data storages such as home location registers (HLRs) or servers that implement the functionality of home location registers, visitor location registers (VLRs) or servers that implement the functionality of visitor location registers, base transceiver stations, base station controllers (BSCs), mobile switching centers (MSCs), and other network nodes that are specifically associated with providing wireless access and connectivity to the electronic devices.

Non-trusted applications 112 are normal applications in the electronic device 102 . When trusted applications 120 are executed in the trusted security zone 124 of the electronic device 102 , peripherals and data of the electronic device 102 may not be accessible to the non-trusted applications 112 . The non-trusted applications 112 are stored in a permissive sector 110 in the memory 126 . The permissive sector 110 of the memory 126 is the normal partition in the memory 126 . Normal applications, the non-trusted applications 112 , may be stored in the permissive sector 110 in the memory 126 . Additionally, non-secure resources may be stored in the permissive sector 110 in the memory 126 .

Trusted applications 120 are authorized secure applications that may store, transmit, or receive confidential data. The trusted applications 120 may execute using higher level of security than the non-trusted applications 112 that are executed in the operating system 108 . For example, the trusted applications 120 may be applications used to perform payments, online banking, and enterprise authentication. The trusted applications 120 may also be applications that entail content protection such as email and corporate VPN. The trusted applications 120 may be applications that handle confidential health records or personal health metrics. Additionally, the trusted applications 120 may be entertainment content streaming services that entail content protection of the data in the form of music and video as well as authentication of the device 102 or the user, or another application that stores, transmits or receives confidential data. The trusted applications 120 may be stored at least in part in the secure partition of the memory 126 , the trusted security zone 124 . The trusted applications 120 may be built in by device makers, original equipment manufacturer (OEM), or installed as users demand them. The trusted applications 120 can originate from different application providers. The trusted applications 120 running in a trusted execution environment may have access to the full power of a device's main processor and memory when the trusted applications 120 are executed with hardware isolation that protects the trusted applications 120 from user installed applications in the main operating system. Software and cryptographic isolation inside the trusted execution environment protect the trusted applications 120 from each other. Hence, an unauthorized trusted application 120 may not have the access to the security resources of another trusted application 120 .

In an embodiment, the trusted security zone 124 is more than just a segment of memory. The trusted security zone 124 may also have a dimension of processing. The trusted security zone 124 may provide the secure execution environment for trusted applications 120 where only trusted applications 120 may operate, safe from attacks. The trusted security zone 124 may be implemented by partitioning both hardware and software resources of the electronic device 102 into two partitions: a secure partition and a normal partition. The secure partition may be implemented by a distinct, separate, or dedicated physical processor, usually the first processor, from the processor by which the normal partition may be implemented, usually the second processor. Alternatively, the secure partition may be implemented by a distinct, separate, or dedicated virtual processor from the virtual processor by which the normal partition may be implemented.

JTAG ports 106 may be used for software debugging for an embedded system, firmware storing/updating for an embedded system, boundary scan testing for printed circuit boards, or other relevant purposes at the manufacturer of a device. When a JTAG port is not disabled after manufacturing, the fundamental cycle/chip level processing state of a device may still be accessed. For example, with a single Chinese character as a password, the fundamental cycle/chip level processing state of a device may be accessed. Additionally, the device may be reprogrammed at the chip level via the JTAG port. Hence, the enabled JTAG port may be utilized as backdoor access that can give attackers full access to a device to harm a device, collect confidential data from the device, or for another unauthorized use. The JTAG ports 106 may be disabled at the manufacturer when the manufacturing and testing process is finished to prevent them from being utilized by attackers for unauthorized uses. However, the device vender/original equipment manufacturer may leave the JTAG ports 106 enabled by oversight or deliberately. If the device vender/original equipment manufacturer fails to disable a JTAG port 106 , there may still be physical, digital, or logical connection to the JTAG port 106 and the JTAG port 106 is still alive. The test port, test wire, test connection, or test voltage of the JTAG port 106 may still be utilized to go to the base of the processor/chip.

In an embodiment, the trusted security zone 124 functions as a test monitor and decides whether an electronic device 102 may be trusted. Usually, actual pins are applied to check poles, functionality, or voltages of the JTAG ports 106 to determine whether the JTAG ports 106 are disabled. However, applying actual pins to test the voltages of the JTAG ports 106 after the chip is assembled/integrated into a circuit board/an electronic device and shipped to the service provider may not be feasible and the process may be emulated with an application in the trusted execution environment or the trusted security zone installer program 128 that tries to enable trust. The trusted security zone installer 128 may go to the right channels/ports/pins of the hardware to check the voltage of the JTAG port 106 , channel, or pin, for example whether the voltage is zero or one. For example, when the JTAG fuse is enabled, the input impedance of the corresponding channel/port/pin may be lowered, which may affect the voltage reference measurement.

For example, the application in the trusted execution environment or the trusted security zone installer 128 may examine the status of the JTAG ports 106 and take action to reduce the risk that the electronic device 102 may be attacked by unauthorized parties. In an embodiment, when the JTAG ports 106 are determined to be disabled, the trusted security zone installer 128 configures the trusted security zone into the electronic device 102 . When the JTAG ports 106 are determined to be disabled, the trusted security zone installer 128 may also generate a JTAG port inspected certificate 122 for the electronic device 102 . Note that the existence of the JTAG port inspected certificate 122 indicates or implies a specific sequence of actions: the JTAG port 106 was checked and determined to be disabled first; after the JTAG port 106 was checked and found to be disabled, then the trusted security zone 124 was installed second; and only after the trusted security zone 124 was installed was the JTAG port inspected certificate 122 built.

When the JTAG ports 106 are determined to be enabled, the trusted security zone installer 128 may send a message to a server computer identifying the electronic device 102 as one with the enabled JTAG ports 106 . When the JTAG ports 106 are determined to be enabled, the trusted security zone installer 128 may prevent configuration of the trusted security zone 124 into the electronic device 102 . The trusted security zone installer 128 may also prevent trusted applications 120 from executing or other applications that attempts to access resources of a higher security level.

At the time of verifying and building up trust before installing the trusted security zone, for example at the service provider side, the trusted security zone installer 128 may be executed behind the trusted execution environment by the processor 104 to test the status of the JTAG (JTAG) ports 106 . For example, the determination of the status of the JTAG (JTAG) ports 106 is helpful before installation of software that requires higher security level than non-trusted applications 112 in the main operating system 108 . In an embodiment, it is determined whether the JTAG port 106 is disabled or enabled after testing the status of the JTAG port 106 . The JTAG ports 106 may be tested by testing whether the fuses of JTAG ports 106 are blown. The determination of the state of the JTAG ports 106 may be carried by reading from the JTAG port 106 addresses.

If the JTAG port 106 on the electronic device 102 is determined to be disabled, the trusted security zone installer 128 may take certain further action. For example, a trusted security zone 124 may be configured into the electronic device 102 . In an embodiment, the trusted security zone 124 provides hardware assisted trust/security. Additionally, a JTAG port inspected certificate 122 may be generated for the device 102 . The trusted execution environment may be included/integrated within an application processor 104 on the electronic device 102 . In an embodiment, the execution environment comprises the trusted security zone 124 . In an embodiment, the trusted security zone 124 may be configured or not be configured at all at the service provider after the electronic device 102 is shipped from the device maker/assembler. When the trusted security zone 124 is configured after the JTAG ports 106 are determined to be disabled, the trusted security zone 124 may be installed in a secure portion of the memory 126 in the electronic device 102 . The JTAG port inspected certificate 122 or existence of the trusted security zone 124 may be taken as an indicator for the fact that the device 102 is stable, reliable, or trustworthy, for example by potential trusted applications 120 . The JTAG port inspected certificate 122 may be stored into a trusted memory area of the trusted security zone 124 . Additionally/alternatively, a parameter value may be stored abstractly indicating that the JTAG port 106 is disabled. The parameter may be stored in a trusted memory area of the secure partition of the memory 126 , the trusted security zone 124 .

On the other hand, if the JTAG port 106 is determined to be enabled, the trusted security zone installer 128 executed on the processor 104 may take precautionary or remediating action. A message may be sent to the server computer 114 identifying the electronic device 102 and indicating that the JTAG ports 106 of the electronic device 102 were determined to be enabled. The message sent to the server computer 114 may be an electronic message via the network 118 . Downloading of confidential information to the electronic device 102 may be prevented by instructions executed on the processor 104 of the electronic device 102 . For example, downloading of a credit card number or a credit card payment application may be prevented. Additionally, downloading of financial applications to the electronic device 102 may be prevented.

Traditionally, JTAG fuses need to be blown to be disabled and so attackers or others would not have access to the memory 126 via the JTAG ports 106 or to the very fundamental core of the processor 104 via the JTAG ports 106 . In an embodiment, the trusted security zone installer 128 may provide hardware assisted trust/security without blowing the JTAG fuses. For example, the trusted security zone installer 128 may be executed on the processor 104 to stop initializing trusted security zone 124 configuration and prevent any future action that tries to start the trusted security zone 124 configuration again. The trusted security zone installer 128 may be executed on the processor 104 preventing configuration of the trusted security zone 124 into the electronic device 102 if the initialization of the trusted security zone 124 has not begun.

A hardware portion of the electronic device 102 intended for installation of a trusted security zone 124 may be marked as invalid or untrusted. For example, the hardware portion of the electronic device 102 intended for installation of a trusted security zone 124 may not be used for any purpose or only for non-trusted applications 112 or information that does not entail higher security level. Additionally, instructions may be executed on the processor 104 preventing execution of software that reads from the JTAG port 106 . For example, throughout the lifetime of the electronic device 102 , the trusted security zone installer 128 may monitor and/or discipline the executables/programs that are loaded on the JTAG ports 106 and may inhibit, pause, and/or shut down the executables/programs that read from the JTAG ports 106 .

The trusted security zone installer 128 may also detect when a program is trying to modify any JTAG port 106 in an over-the-air fashion and may inhibit, pause, and/or shut down the corresponding program. In an embodiment, an untrusted logo may be displayed on a display of the electronic device 102 when the JTAG port 106 is determined to be enabled. For example, an untrusted logo may be displayed when the electronic device 102 is turned on.

The trusted security zone installer 128 may be executed on the processor 104 to detect a physical connection to the JTAG port 106 . If a physical connection to the JTAG port 106 is detected, the trusted security zone installer 128 may be executed on the processor 104 preventing execution of trusted applications 120 .

Turning now to FIG. 2 , a method 200 is described. At block 202 , instructions are executed on a processor 104 of the portable electronic device 102 that determines the state of a JTAG port 106 of the portable electronic device 102 . For example, instructions are executed on the processor 104 to determine whether the JTAG port 106 is disabled. For example, the determination process of the status of the JTAG port 106 may comprise the determination of whether the fuses of the JTAG ports 106 are blown. The determination process of the status of the JTAG port 106 may further comprise reading from the JTAG port 106 addresses.

If the JTAG port is not disabled, the method 200 proceeds to block 212 . If the JTAG port is disabled, the method 200 proceeds to block 206 . At block 212 , instructions are executed on the processor 104 preventing configuration of the trusted security zone 124 into the portable electronic device 102 . When the JTAG port 106 is enabled, the electronic device is considered as unstable, unreliable, or untrustworthy, and so the trusted security zone may not be configured into the electronic device 102 . At block 206 , the trusted security zone 124 is configured into the portable electronic device 102 , wherein the trusted security zone 124 provides hardware assisted trust or root of trust. At block 208 , after the trusted security zone is configured into the portable electronic device, instructions are executed on the processor 104 creating a JTAG port inspected certificate 122 . The existence of the JTAG port inspected certificate 122 indicates or implies that the JTAG port 106 was checked, determined to be disabled, and the trusted security zone 124 was installed. With the JTAG port inspected certificate 122 , the electronic device 102 may be taken as stable, reliable, or trustworthy, for example by potential trusted applications 120 . With the JTAG port inspected certificate 122 , the electronic device 102 may be taken as stable, reliable, or trustworthy by confidential information that requires higher security level than normal information processed in the operating system 108 or stored in the permissive sector of the memory 126 . Additionally, the JTAG inspected certificate 122 may be stored—off device—for future use in demonstrating integrity of device trust—as when a claim for unauthorized disclosure of confidential information or hacking the device 102 is advanced. At block 210 , the JTAG port inspected certificate 122 is stored into a trusted memory area of the trusted security zone 124 . The JTAG port inspected certificate 122 may not be accessible with unauthorized attempts by the non-trusted applications 112 , which may assure the JTAG port inspected certificate 122 as a trustworthy indicator for the credibility of the electronic device.

Turning now to FIG. 3 , a method 300 is described. At block 302 , instructions are executed on a processor 104 of the electronic device 102 that determine the state of a JTAG port 106 of the electronic device 102 . At block 304 , it is determined whether the JTAG port 106 is enabled. If the result of block 304 is false, which means the JTAG port 106 is disabled, end the program. If the result of block 304 is true, which means the JTAG port 106 is enabled, block 306 is executed and instructions are executed on the processor 104 preventing execution of software that reads from the JTAG port 106 . When the JTAG port 106 is enabled, the electronic device 102 is considered to be unreliable and the electronic device 102 may be vulnerable to attackers 116 via the JTAG port 106 . The JTAG port 106 may be exploited by attackers to access the memory 126 and reprogram the electronic device 102 . Thus block 306 is helpful when the JTAG port 106 has been left enabled. At block 308 , instructions are executed on the processor 104 of the electronic device 102 to detect a physical connection to the JTAG port 106 . The possible ways that the JTAG port 106 is enabled comprise digital, physical, or logical connection to the JTAG port 106 . Here instructions are executed to detect specifically physical connection. At block 310 , it is determined whether a physical connection to the JTAG port 106 is detected. If the result of block 310 is false, which means no physical connection to the JTAG port 106 is detected, end the program. If the result of block 310 is true, which means a physical connection to the JTAG port 106 is detected, block 312 is executed. At block 312 , instructions are executed on the processor 104 preventing execution of trusted applications 120 . Trusted applications 120 entail higher security level, but the electronic device 102 may not be reliable when the JTAG port 106 is enabled. Hence, the trusted applications may not be allowed to be executed on the electronic device 102 .

FIG. 4 depicts the mobile device 400 , which is operable for implementing aspects of the present disclosure, but the present disclosure should not be limited to these implementations. Though illustrated as a mobile phone, the mobile device 400 may take various forms including a wireless handset, a pager, a personal digital assistant (PDA), a gaming device, or a media player. The mobile device 400 includes a display 402 and a touch-sensitive surface and/or keys 404 for input by a user. The mobile device 400 may present options for the user to select, controls for the user to actuate, and/or cursors or other indicators for the user to direct. The mobile device 400 may further accept data entry from the user, including numbers to dial or various parameter values for configuring the operation of the handset. The mobile device 400 may further execute one or more software or firmware applications in response to user commands. These applications may configure the mobile device 400 to perform various customized functions in response to user interaction. Additionally, the mobile device 400 may be programmed and/or configured over-the-air, for example from a wireless base station, a wireless access point, or a peer mobile device 400 . The mobile device 400 may execute a web browser application which enables the display 402 to show a web page. The web page may be obtained via wireless communications with a base transceiver station, a wireless network access node, a peer mobile device 400 or any other wireless communication network or system.

FIG. 5 shows a block diagram of the mobile device 400 . While a variety of known components of handsets are depicted, in an embodiment a subset of the listed components and/or additional components not listed may be included in the mobile device 400 . The mobile device 400 includes a digital signal processor (DSP) 502 and a memory 504 . As shown, the mobile device 400 may further include an antenna and front end unit 506 , a radio frequency (RF) transceiver 508 , a baseband processing unit 510 , a microphone 512 , an earpiece speaker 514 , a headset port 516 , an input/output interface 518 , a removable memory card 520 , a universal serial bus (USB) port 522 , an infrared port 524 , a vibrator 526 , a keypad 528 , a touch screen liquid crystal display (LCD) with a touch sensitive surface 530 , a touch screen/LCD controller 532 , a camera 534 , a camera controller 536 , and a global positioning system (GPS) receiver 538 . In an embodiment, the mobile device 400 may include another kind of display that does not provide a touch sensitive screen. In an embodiment, the DSP 502 may communicate directly with the memory 504 without passing through the input/output interface 518 . Additionally, in an embodiment, the mobile device 400 may comprise other peripheral devices that provide other functionality.

The DSP 502 or some other form of controller or central processing unit operates to control the various components of the mobile device 400 in accordance with embedded software or firmware stored in memory 504 or stored in memory contained within the DSP 502 itself. In addition to the embedded software or firmware, the DSP 502 may execute other applications stored in the memory 504 or made available via information carrier media such as portable data storage media like the removable memory card 520 or via wired or wireless network communications. The application software may comprise a compiled set of machine-readable instructions that configure the DSP 502 to provide the desired functionality, or the application software may be high-level software instructions to be processed by an interpreter or compiler to indirectly configure the DSP 502 .

The DSP 502 may communicate with a wireless network via the analog baseband processing unit 510 . In some embodiments, the communication may provide Internet connectivity, enabling a user to gain access to content on the Internet and to send and receive e-mail or text messages. The input/output interface 518 interconnects the DSP 502 and various memories and interfaces. The memory 504 and the removable memory card 520 may provide software and data to configure the operation of the DSP 502 . Among the interfaces may be the USB port 522 and the infrared port 524 . The USB port 522 may enable the mobile device 400 to function as a peripheral device to exchange information with a personal computer or other computer system. The infrared port 524 and other optional ports such as a Bluetooth® interface or an IEEE 802.11 compliant wireless interface may enable the mobile device 400 to communicate wirelessly with other nearby handsets and/or wireless base stations.

The keypad 528 couples to the DSP 502 via the interface 518 to provide one mechanism for the user to make selections, enter information, and otherwise provide input to the mobile device 400 . Another input mechanism may be the touch screen LCD 530 , which may also display text and/or graphics to the user. The touch screen LCD controller 532 couples the DSP 502 to the touch screen LCD 530 . The GPS receiver 538 is coupled to the DSP 502 to decode global positioning system signals, thereby enabling the mobile device 400 to determine its position.

FIG. 6A illustrates a software environment 602 that may be implemented by the DSP 502 . The DSP 502 executes operating system software 604 that provides a platform from which the rest of the software operates. The operating system software 604 may provide a variety of drivers for the handset hardware with standardized interfaces that are accessible to application software. The operating system software 604 may be coupled to and interact with application management services (AMS) 606 that transfer control between applications running on the mobile device 400 . Also shown in FIG. 6A are a web browser application 608 , a media player application 610 , and JAVA applets 612 . The web browser application 608 may be executed by the mobile device 400 to browse content and/or the Internet, for example when the mobile device 400 is coupled to a network via a wireless link. The web browser application 608 may permit a user to enter information into forms and select links to retrieve and view web pages. The media player application 610 may be executed by the mobile device 400 to play audio or audiovisual media. The JAVA applets 612 may be executed by the mobile device 400 to provide a variety of functionality including games, utilities, and other functionality.

FIG. 6B illustrates an alternative software environment 620 that may be implemented by the DSP 502 . The DSP 502 executes operating system software 628 (for example an operating system kernel) and an execution runtime 630 . The DSP 502 executes applications 622 that may execute in the execution runtime 630 and may rely upon services provided by the application framework 624 . Applications 622 and the application framework 624 may rely upon functionality provided via the libraries 626 .

FIG. 7 illustrates a computer system 380 suitable for implementing one or more embodiments disclosed herein. The computer system 380 includes a processor 382 (which may be referred to as a central processor unit or CPU) that is in communication with memory devices including secondary storage 384 , read only memory (ROM) 386 , random access memory (RAM) 388 , input/output (I/O) devices 390 , and network connectivity devices 392 . The processor 382 may be implemented as one or more CPU chips.

It is understood that by programming and/or loading executable instructions onto the computer system 380 , at least one of the CPU 382 , the RAM 388 , and the ROM 386 are changed, transforming the computer system 380 in part into a particular machine or apparatus having the novel functionality taught by the present disclosure. It is fundamental to the electrical engineering and software engineering arts that functionality that can be implemented by loading executable software into a computer can be converted to a hardware implementation by well known design rules. Decisions between implementing a concept in software versus hardware typically hinge on considerations of stability of the design and numbers of units to be produced rather than any issues involved in translating from the software domain to the hardware domain. Generally, a design that is still subject to frequent change may be preferred to be implemented in software, because re-spinning a hardware implementation is more expensive than re-spinning a software design. Generally, a design that is stable that will be produced in large volume may be preferred to be implemented in hardware, for example in an application specific integrated circuit (ASIC), because for large production runs the hardware implementation may be less expensive than the software implementation. Often a design may be developed and tested in a software form and later transformed, by well known design rules, to an equivalent hardware implementation in an application specific integrated circuit that hardwires the instructions of the software. In the same manner as a machine controlled by a new ASIC is a particular machine or apparatus, likewise a computer that has been programmed and/or loaded with executable instructions may be viewed as a particular machine or apparatus.

The secondary storage 384 is typically comprised of one or more disk drives or tape drives and is used for non-volatile storage of data and as an over-flow data storage device if RAM 388 is not large enough to hold all working data. Secondary storage 384 may be used to store programs which are loaded into RAM 388 when such programs are selected for execution. The ROM 386 is used to store instructions and perhaps data which are read during program execution. ROM 386 is a non-volatile memory device which typically has a small memory capacity relative to the larger memory capacity of secondary storage 384 . The RAM 388 is used to store volatile data and perhaps to store instructions. Access to both ROM 386 and RAM 388 is typically faster than to secondary storage 384 . The secondary storage 384 , the RAM 388 , and/or the ROM 386 may be referred to in some contexts as computer readable storage media and/or non-transitory computer readable media.

I/O devices 390 may include printers, video monitors, liquid crystal displays (LCDs), touch screen displays, keyboards, keypads, switches, dials, mice, track balls, voice recognizers, card readers, paper tape readers, or other well-known input devices.

The network connectivity devices 392 may take the form of modems, modem banks, Ethernet cards, universal serial bus (USB) interface cards, serial interfaces, token ring cards, fiber distributed data interface (FDDI) cards, wireless local area network (WLAN) cards, radio transceiver cards such as code division multiple access (CDMA), global system for mobile communications (GSM), long-term evolution (LTE), worldwide interoperability for microwave access (WiMAX), and/or other air interface protocol radio transceiver cards, and other well-known network devices. These network connectivity devices 392 may enable the processor 382 to communicate with the Internet or one or more intranets. With such a network connection, it is contemplated that the processor 382 might receive information from the network, or might output information to the network in the course of performing the above-described method steps. Such information, which is often represented as a sequence of instructions to be executed using processor 382 , may be received from and outputted to the network, for example, in the form of a computer data signal embodied in a carrier wave.

Such information, which may include data or instructions to be executed using processor 382 for example, may be received from and outputted to the network, for example, in the form of a computer data baseband signal or signal embodied in a carrier wave. The baseband signal or signal embedded in the carrier wave, or other types of signals currently used or hereafter developed, may be generated according to several methods well known to one skilled in the art. The baseband signal and/or signal embedded in the carrier wave may be referred to in some contexts as a transitory signal.

The processor 382 executes instructions, codes, computer programs, scripts which it accesses from hard disk, floppy disk, optical disk (these various disk based systems may all be considered secondary storage 384 ), ROM 386 , RAM 388 , or the network connectivity devices 392 . While only one processor 382 is shown, multiple processors may be present. Thus, while instructions may be discussed as executed by a processor, the instructions may be executed simultaneously, serially, or otherwise executed by one or multiple processors. Instructions, codes, computer programs, scripts, and/or data that may be accessed from the secondary storage 384 , for example, hard drives, floppy disks, optical disks, and/or other device, the ROM 386 , and/or the RAM 388 may be referred to in some contexts as non-transitory instructions and/or non-transitory information.

In an embodiment, the computer system 380 may comprise two or more computers in communication with each other that collaborate to perform a task. For example, but not by way of limitation, an application may be partitioned in such a way as to permit concurrent and/or parallel processing of the instructions of the application. Alternatively, the data processed by the application may be partitioned in such a way as to permit concurrent and/or parallel processing of different portions of a data set by the two or more computers. In an embodiment, virtualization software may be employed by the computer system 380 to provide the functionality of a number of servers that is not directly bound to the number of computers in the computer system 380 . For example, virtualization software may provide twenty virtual servers on four physical computers. In an embodiment, the functionality disclosed above may be provided by executing the application and/or applications in a cloud computing environment. Cloud computing may comprise providing computing services via a network connection using dynamically scalable computing resources. Cloud computing may be supported, at least in part, by virtualization software. A cloud computing environment may be established by an enterprise and/or may be hired on an as-needed basis from a third party provider. Some cloud computing environments may comprise cloud computing resources owned and operated by the enterprise as well as cloud computing resources hired and/or leased from a third party provider.

In an embodiment, some or all of the functionality disclosed above may be provided as a computer program product. The computer program product may comprise one or more computer readable storage medium having computer usable program code embodied therein to implement the functionality disclosed above. The computer program product may comprise data structures, executable instructions, and other computer usable program code. The computer program product may be embodied in removable computer storage media and/or non-removable computer storage media. The removable computer readable storage medium may comprise, without limitation, a paper tape, a magnetic tape, magnetic disk, an optical disk, a solid state memory chip, for example analog magnetic tape, compact disk read only memory (CD-ROM) disks, floppy disks, jump drives, digital cards, multimedia cards, and others. The computer program product may be suitable for loading, by the computer system 380 , at least portions of the contents of the computer program product to the secondary storage 384 , to the ROM 386 , to the RAM 388 , and/or to other non-volatile memory and volatile memory of the computer system 380 . The processor 382 may process the executable instructions and/or data structures in part by directly accessing the computer program product, for example by reading from a CD-ROM disk inserted into a disk drive peripheral of the computer system 380 . Alternatively, the processor 382 may process the executable instructions and/or data structures by remotely accessing the computer program product, for example by downloading the executable instructions and/or data structures from a remote server through the network connectivity devices 392 . The computer program product may comprise instructions that promote the loading and/or copying of data, data structures, files, and/or executable instructions to the secondary storage 384 , to the ROM 386 , to the RAM 388 , and/or to other non-volatile memory and volatile memory of the computer system 380 .

In some contexts, the secondary storage 384 , the ROM 386 , and the RAM 388 may be referred to as a non-transitory computer readable medium or a computer readable storage media. A dynamic RAM embodiment of the RAM 388 , likewise, may be referred to as a non-transitory computer readable medium in that while the dynamic RAM receives electrical power and is operated in accordance with its design, for example during a period of time during which the computer 380 is turned on and operational, the dynamic RAM stores information that is written to it. Similarly, the processor 382 may comprise an internal RAM, an internal ROM, a cache memory, and/or other internal non-transitory storage blocks, sections, or components that may be referred to in some contexts as non-transitory computer readable media or computer readable storage media.

While several embodiments have been provided in the present disclosure, it should be understood that the disclosed systems and methods may be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted or not implemented.

Also, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as directly coupled or communicating with each other may be indirectly coupled or communicating through some interface, device, or intermediate component, whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the spirit and scope disclosed herein.