Integrity verification using a peripheral device

A peripheral device includes an interface configured to communicate with a computer, the peripheral device; logic configured to perform an integrity verification of an operating system of the computer; and a display configured to display a result of the integrity verification. A method for integrity verification of a computer using a peripheral device includes connecting the peripheral device to the computer; sending a challenge from the device to the computer; computing attestation data using the challenge and information stored in the computer, retrieving the attestation data from the computer by a client program running on the computer; sending the attestation data to the peripheral device; and verifying the attestation data by the peripheral device.

BACKGROUND

This disclosure relates generally to the field of computer integrity verification.

Root kits, Trojan horses, or other types of malicious code may compromise the operating system of a computer, thereby compromising the trustworthiness of all code running on the computer. To determine if a computer has been compromised, it is relevant to determine if the computer is booted with a verifiably sound and trustworthy operating system. Trusted Platform Module (TPM), technology (see https://www.trustedcomputinggroup.org/groups/tpm/ for more information on TPM) may be used for trust verification of a computer. TPM provides a secure hardware location on a computer that stores a measurement of all software that is executed by the computer during the boot process; the measurement may be used for integrity verification.

TPM is included in many computer platforms, including many brands of personal computers. A TPM enables integrity validation of code when the computer boots by performing hardware-protected measurement and attestation to a stored log. In hardware-protected measurement, the computer generates and securely stores a cryptographic hash value of all code involved in the boot process in the secure TPM storage. The computer then generates a log entry for the cryptographic hash value, and securely stores the log entry in the TPM. Attestation to the stored log occurs when, in response to a randomly generated challenge from an outside piece of hardware, the computer produces a signature from a log entry in the TPM that allows the outside piece of hardware to verify the log entry by comparing the log entry to hashes of known, trusted code. At computer startup, code on the computer, including but not limited to the basic input/output system (BIOS), the bootloader, the kernel, and any applications, is first loaded into memory, then measured, and then executed. The measurement of the code is stored in a log in the TPM. A piece of malicious code is unable to erase its associated log entry, as the log entry is stored in the secure TPM before the execution of the code starts.

To complete attestation, the TPM requires a separate, trusted host, known as a verifier, to issue a challenge and perform attestation, thereby determining if a given computer is booted with a trusted operating system. An owner of a personal computer may not have a separate host that may act as verifier. The benefits of TPM verification are not available to users that do not have a separate verifier computer.

BRIEF SUMMARY

An exemplary embodiment of a peripheral device includes an interface configured to communicate with a computer, the peripheral device; logic configured to perform an integrity verification of an operating system of the computer; and a display configured to display a result of the integrity verification.

An exemplary embodiment of a method for integrity verification of a computer using a peripheral device includes connecting the peripheral device to the computer; sending a challenge from the device to the computer; computing attestation data using the challenge and information stored in the computer, retrieving the attestation data from the computer by a client program running on the computer; sending the attestation data to the peripheral device; and verifying the attestation data by the peripheral device.

An exemplary embodiment of a system for verifying the integrity of a computer using a peripheral device includes a computer, the computer comprising an operating system; and a peripheral device in communication with the computer, the peripheral device being configured to perform an integrity verification of the operating system.

Additional features are realized through the techniques of the present exemplary embodiment. Other embodiments are described in detail herein and are considered a part of what is claimed. For a better understanding of the features of the exemplary embodiment, refer to the description and to the drawings.

DETAILED DESCRIPTION

Embodiments of systems and methods for integrity verification using a peripheral device are provided, with exemplary embodiments being discussed below in detail.

A TPM on a computer may communicate with a relatively small, cheap type of hardware, including but not limited to a universal serial bus (USB, see http://www.usb.org for general information on USB) peripheral device, to verify the integrity of the computer. The peripheral device may run the TPM verification protocol and display a result of the verification on, for example, an embedded display, by using lights, or by other appropriate means.

Embodiments of a USB device may be small in size, and in some embodiments the shape of the USB device may be akin to a key fob. The functionality provided by USB devices varies widely. USB devices may include but are not limited to USB flash memory devices, network devices such as wireless network adapters for 802.11 WLAN or Bluetooth, keyboards, mice, webcams, cryptographic tokens, and DVB-T adapters for TV and radio reception.

A USB device comprises a communication interface, or interconnect, conforming to the USB standard. The USB communication interface comprises a serial bus system designed to allow many different types of USB peripherals to be connected to a computer using a single standardized interface socket, providing plug-and-play capability. A system comprising a USB device may be divided into three parts: the USB host (for example, a computer to which the USB device is connected), the USB device, and the USB interconnect. There are various versions of the USB standard available. USB 1.1 supports two speeds, low speed at 1.5 Mbits/s, and full speed at 12 Mbits/s. USB 2.0 supports higher speeds at 480 Mbits/s. Faster versions of USB are in development, as is wireless USB. Embodiments of a peripheral device used for integrity verification may incorporate any appropriate version of USB technology.

A USB device may require a specialized device driver in order to communicate with the operating system of a computer, or the USB device may conform to a standardized device class, for which an operating system may provide a standard device drivers. Device classes are defined for a wide range of USB peripheral devices such as hub devices, mass storage devices such as memory sticks, or human interface devices such as computer keyboards and mice, network interface devices, and many more.

FIG. 1illustrates an embodiment of a peripheral device100that may be used as a peripheral device for integrity verification. Peripheral device100is an embedded system comprising a microprocessor core104, memory controller105, static RAM101, flash memory102, ROM103, system controller107, which may comprise an interrupt controller, timers, and power management. Communications controllers in the peripheral device100may include USART controller111, SPI controller110, I2C controller109, and USB communications controller112. The various components that comprise peripheral device100may be provided by a single system-on-chip (SOC) device, by an application specific integrated circuit (ASIC) chip, or by several commercial off the shelf (COTS) components in some embodiments. Depending on the functionality of peripheral device100, function-specific hardware113complements the system. Function-specific hardware113may include but is not limited to a display device. Peripheral device100may act as a general purpose embedded computing device with a USB client interface. Software loaded on peripheral device100may determine the functionality of the device.

FIG. 2illustrates an embodiment of a computer system200comprising a peripheral device for verification. Computer203comprises operating system204, which in turn supports network stack205, peripheral device drivers206, and TPM device drivers207. Network stack205communicates with a database of trusted configurations202on configuration server201via a network connection, and with peripheral device drivers206. Peripheral device drivers206communicate with client program210on peripheral device209via an interface. Client program210may communicate with display211on peripheral device209. TPM device drivers207communicate with TPM208on computer203. In some embodiments, peripheral device209may be a read-only USB device.

FIG. 3illustrates an embodiment of a method300for integrity verification using a peripheral device, which is discussed with reference toFIG. 2. In block301, computer203commences the boot process, booting operating system204, including network stack204, peripheral device drivers206, and TPM device deriver207. In block302, operating system204records attestation data and log information for the booted software in TPM208via TPM device drivers207. In block303, peripheral device209connects to the computer. Communication with peripheral device209may require the operating system204to possess a driver suitable for communicating with the device class of peripheral device209.

In block304, client program210is launched; the client program210may be loaded from peripheral device209and launched on computer203, or, alternatively, the client program210may be pre-installed on computer203. In block305, integrity verification of the attestation data stored in TPM208is performed by the peripheral device; integrity verification is discussed in further detail below with regard toFIG. 4. Lastly, in block306, peripheral device209signals via display211the result of the verification. In some embodiments, the display211may display the words “OK” or “FAIL” to signal that the verification was successful or unsuccessful, or the display211may show a green light to indicate successful verification, and a red light to signal unsuccessful verification.

FIG. 4illustrates an embodiment of a method400for integrity verification. In block401, peripheral device209generates a random challenge. In block402, the random challenge is sent to client program210. In block403, client program210sends the challenge to TPM208via TPM device drivers207. In block404, TPM208outputs signed attestation data and log information to client program210in response to the challenge. In block405, client program210sends the attestation data and the log information to peripheral device209to be verified. In block406, the attestation data and log information are verified by peripheral device209. Verification of the attestation data and log information by peripheral device209may be performed in various ways. The peripheral device209may compare the attestation and log information received from the TPM208on computer203to a known list of acceptable attestation values. Client program210may also compile a list of certificates that enable the peripheral device209to verify the attestation data from the log data, or the client program may obtain a correctness certificate from a database of trusted configurations202via a network connection.

To verify the attestation data, peripheral device209requires access to a list of acceptable attestation values. Peripheral device209may also require any information necessary for verification of a certificate, such as keys used to generate any third-party certificates. In some embodiments, peripheral device209is preconfigured with this information. In an alternative embodiment, peripheral device209may download this information from a configuration server201. To download a key, peripheral device209may establish a connection, including but not limited to a secure socket layer (SSL) connection, to configuration server201via peripheral device drivers206and network stack205to download the public key. Such downloads may be performed upon request from a user, or performed automatically each time peripheral device209is used. If peripheral device209is offline, or cannot download the latest key information for some other reason, peripheral device209may use the most recent information obtained from configuration server201.

In some embodiments, the functionality of peripheral device209may be integrated into a keyboard or other piece of peripheral hardware. In some embodiments, peripheral device209may possess additional functionality, including but not limited to fingerprint reading or data storage. If the TPM verification process is successful, peripheral device209may enable the additional functionality. A peripheral device209comprising an external fingerprint reader may verify the integrity of computer203before sending a scanned fingerprint to the computer. In this manner, it may be ensured that scanned fingerprints are only sent to a trusted computer.

FIG. 5illustrates an example of a computer500having capabilities, which may be utilized by exemplary embodiments of systems and methods for integrity verification using a peripheral device as embodied in software. Various operations discussed above may utilize the capabilities of the computer500. One or more of the capabilities of the computer500may be incorporated in any element, module, application, and/or component discussed herein.

The computer500includes, but is not limited to, PCs, workstations, laptops, PDAs, palm devices, servers, storages, and the like. Generally, in terms of hardware architecture, the computer500may include one or more processors510, memory520, and one or more input and/or output (I/O) devices570that are communicatively coupled via a local interface (not shown). The local interface can be, for example but not limited to, one or more buses or other wired or wireless connections, as is known in the art. The local interface may have additional elements, such as controllers, buffers (caches), drivers, repeaters, and receivers, to enable communications. Further, the local interface may include address, control, and/or data connections to enable appropriate communications among the aforementioned components.

The processor510is a hardware device for executing software that can be stored in the memory520. The processor510can be virtually any custom made or commercially available processor, a central processing unit (CPU), a data signal processor (DSP), or an auxiliary processor among several processors associated with the computer500, and the processor510may be a semiconductor based microprocessor (in the form of a microchip) or a macroprocessor.

The software in the memory520may include one or more separate programs, each of which comprises an ordered listing of executable instructions for implementing logical functions. The software in the memory520includes a suitable operating system (O/S)550, compiler540, source code530, and one or more applications560in accordance with exemplary embodiments. As illustrated, the application560comprises numerous functional components for implementing the features and operations of the exemplary embodiments. The application560of the computer500may represent various applications, computational units, logic, functional units, processes, operations, virtual entities, and/or modules in accordance with exemplary embodiments, but the application560is not meant to be a limitation.

The operating system550controls the execution of other computer programs, and provides scheduling, input-output control, file and data management, memory management, and communication control and related services. Application560for implementing exemplary embodiments may be applicable on all commercially available operating systems.

Application560may be a source program, executable program (object code), script, or any other entity comprising a set of instructions to be performed. When a source program, then the program is usually translated via a compiler (such as the compiler540), assembler, interpreter, or the like, which may or may not be included within the memory520, so as to operate properly in connection with the OS550. Furthermore, the application560can be written as any type of available programming language, including but not limited to an object oriented programming language, which has classes of data and methods, or a procedure programming language, which has routines, subroutines, and/or functions, for example but not limited to, C, C++, C#, Pascal, BASIC, API calls, HTML, XHTML, XML, ASP scripts, FORTRAN, COBOL, Perl, Java, ADA, .NET, and the like.

The I/O devices570may include input devices such as, for example but not limited to, a mouse, keyboard, scanner, microphone, camera, etc. Furthermore, the I/O devices570may also include output devices, for example but not limited to a printer, display, etc. Finally, the I/O devices570may further include devices that communicate both inputs and outputs, for instance but not limited to, a NIC or modulator/demodulator (for accessing remote devices, other files, devices, systems, or a network), a radio frequency (RF) or other transceiver, a telephonic interface, a bridge, a router, etc. The I/O devices570also include components for communicating over various networks, such as the Internet or intranet.

If the computer500is a PC, workstation, or the like, the software in the memory520may further include a basic input output system (BIOS) (omitted for simplicity). The BIOS is a set of essential software routines that initialize and test hardware at startup, start the O/S550, and support the transfer of data among the hardware devices. The BIOS is stored in some type of read-only-memory, such as ROM, PROM, EPROM, EEPROM or the like, so that the BIOS can be executed when the computer500is activated.

When the computer500is in operation, the processor510is configured to execute software stored within the memory520, to communicate data to and from the memory520, and to generally control operations of the computer500pursuant to the software. The application560and the OS550are read, in whole or in part, by the processor510, perhaps buffered within the processor510, and then executed.

When the application560is implemented in software it should be noted that the application560can be stored on virtually any computer readable medium for use by or in connection with any computer related system or method. In the context of this document, a computer readable medium may be an electronic, magnetic, optical, or other physical device or means that can contain or store a computer program for use by or in connection with a computer related system or method.

The application560can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. In the context of this document, a “computer-readable medium” can be any means that can store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. The computer readable medium can be, for example but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium.

The technical effects and benefits of exemplary embodiments include the ability to verify that the operating system of a computer has not been compromised without a separate full-fledged and generally expensive machine to act as the verifier, allowing for increased security.