RU2527758C2 - Method for concealed storage of confidential data in secure non-volatile memory and device therefor - Google Patents

Abstract

FIELD: physics, computer engineering.

SUBSTANCE: invention relates to means of storing confidential data stored in a non-volatile memory region. The device consists of two non-volatile memory regions - an open region and a concealed region, wherein the memory regions are physically separated from each other. The concealed memory is accessed by activating a detector known to a limited circle of individuals. The memory is accessed through a serial interface and prevents simultaneous access to the open and concealed memory regions, which makes it harder to detect the concealed memory region and access data stored therein.

EFFECT: improved data security.

5 cl, 2 dwg

Description

The present invention relates to the field of microelectronics, and in particular to electronic products, for example, equipment designed to store confidential data recorded in the field of non-volatile memory, which must be protected from illegal reading (for example, credit card codes, encryption keys).

When confidential data is stored on a portable device, it is possible to lose or compromise it, if an intruder gains access to memory on a device designed to store confidential data, there is a risk of gaining access to confidential data using one of the known methods of reading data from non-volatile memory, therefore it is important, firstly, to hide the fact of the presence of confidential data in the device and, secondly, to ensure the discontinuity of normal operating modes and modes p Works with sensitive data in time and space.

Various methods are known in the art for covert storage of sensitive data in non-volatile memory. For example, in US patent No. 2008/0022034 A1 [1] describes a system, method and device for its implementation with sector-separated flash memory, when the memory is divided into three or more segments, the first segment is for hidden service information and is not displayed the user in the process of use, the second segment is intended for read-only use and is available for user manipulation, the third segment is available to the user for reading and writing. The disadvantage of this technical solution for storing confidential data is that physically all data is placed on one chip, which means that it can be obtained by reading on a special programmer after evaporating the chip with the recorded data from the carrier PCB.

US Patent No. 201110093395 A1 [2] describes a device with a hidden memory area, which is intended for access by a limited circle of end users to information (in particular, advertising) when accessing the device. In this case, when restricting access to special information, encryption keys are used, which are stored in a hidden memory area together with digital information intended for the end user. The disadvantage of this technical solution is the lack of physical distinction between the hidden area of memory intended for storing keys and the area of memory in which information intended for a limited circle of end users is stored, since physical access to memory bypassing the control circuit allows access to final information and to the keys.

US Pat. No. 2006/0288166 A1 [3] describes a device based on non-volatile memory and the procedure for accessing said memory. Non-volatile memory is divided into areas, one of these areas is protected (encoded or encrypted). Access to the protected memory area is via software. The technical solution described in this patent does not protect memory from physical readings, as well as from remote changes, since when connected to a computer, it is possible to modify the memory, including remote memory, by connecting to a computer network.

US Pat. No. 2010/0005317 [4] describes a device that includes a non-volatile memory that stores a secret key for accessing data, the key being destroyed if the device’s operating mode is not as expected, namely, the device is put into low power mode, not communication over the network, etc. The main disadvantage of this technical solution is the possibility of an unintentional transfer of the device to the mode associated with the removal of the secret key, which will not allow access to data.

In US patent No. 2009/0292893 A1 [5] and No. 2009/0292894 A1 [6] describes a microprocessor device with encryption and access control functions for protected non-volatile memory, and non-volatile protected memory can be located both inside the microprocessor and on an external device . The main disadvantage of this technical solution is its complexity associated with the need to create and use a specialized processor to access non-volatile protected memory, with the corresponding complication of the general logic of the system, as well as the fact that access to protected memory can be carried out in any processor operating mode.

Closest to the claimed technical solution is US patent No. 7907447 [7], which describes a secure device with non-volatile memory and a method of protecting memory in this device. The main feature of this technical solution is the spatial diversity of non-volatile memory on the chip and the obfuscation method built on it, which is used to write and read data. The main disadvantages of this technical solution are the complication of the design and logic of working with the device, the fact that the data from the segmented memory is physically located on one chip and can be read by at least one of the existing methods of reading data from flash memory.

From the existing level of technology it is known that access from an external device with non-volatile memory to the computer bus can be carried out in different modes, these modes are currently supported by the main operating systems and are part of the specification for serial data buses. [8]

The problem to which the present invention is directed, is to eliminate the disadvantages of the prototype, namely: simplifying access to data, simplifying the logic of the device, hiding the fact of the presence of confidential data in the device, complicating access to hidden confidential data, ensuring disruption of normal operating modes and operating modes with confidential data in time and space, the rejection of special methods for placing data in memory.

The problem is solved due to the fact that the claimed method of storing confidential data in non-volatile memory, which uses at least two non-volatile memory, one of which is a hidden area for storing confidential data and is physically separated from the memory for general use (performed in in the form of a separate crystal in a separate case or in a caseless design), characterized in that access to a hidden area of memory for storing confidential data under no circumstances can be carried out simultaneously with access to an open area of public memory, and, conversely, access to an open area of memory at a given moment excludes the possibility of access to a closed area of memory, and a targeted physical effect on the detector included in the device is used to switch the access mode that implements the described method, known to a limited circle of people for whom data written in a hidden protected area of non-volatile memory is intended storage of confidential data, and at least one protected area of non-volatile memory must be made as a functional unit of the on-chip system, which, in addition, monitors the detector (monitoring of effects) and switching data transfer modes in case of detecting the correct effect and which communicates with an external computing environment through a serial data transfer interface, and depending on the type of detector used (operating on toyanno or with only the external device is connected to the serial bus) device is powered via the serial interface or operates autonomously from the battery, is part of the device.

At the same time, it is advisable to use a controller (system on a chip) to control the access to an open memory area to place a protected memory area. This option will prevent physical access to the protected memory area by evaporating the microcircuit with information for reading on the programmer.

The technical result provided by the given set of features is the difficulty of obtaining unauthorized access to confidential information, since the presence of a protected area of non-volatile memory when working with an open area of memory is not definable, since the same bus is used to access the closed memory as for access to the open area of non-volatile memory, and another protocol is used, provided for by the specification of the bus interface, also when trying to physically Skog access to protected memory region is not detected, as physically located on another chip.

The invention is illustrated by drawings, which depict:

Figure 1 (a) schematically shows a variant of the device with a non-volatile memory area for storing confidential data in a mode of working with public memory; when transferring data via the serial interface, under no circumstances is the protected area affected;

Figure 1 (b) schematically shows a variant of the device with a non-volatile memory area for storing confidential data in a mode of operation with a protected non-volatile memory area; when transmitting data via the serial interface, only a hidden area of non-volatile memory is available for storing sensitive data.

A device that implements the proposed storage method (Fig. 1 (a), 1 (b)) consists of a printed circuit board (6), on which the system on a chip is located - a microcontroller or microprocessor (2) with a data transmission control unit (3), the area of protected non-volatile memory (5), made in the form of a separate functional unit of the system on a chip, public non-volatile memory (4), made in the form of a separate microcircuit or chip in a package, the data exchange with an external computing environment, including, but not limited to When using a personal computer, it is carried out through a serial data transfer interface (1), including, but not limited to, a universal USB serial bus, and in the open area access mode access to the closed area is not possible under any conditions (Fig. 1 (a)) , while in the access mode to the protected area of non-volatile memory, on the contrary, access to the shared memory area is impossible (Fig. 1 (b)), moreover, switching from one mode to another is carried out by acting on the detector, which is classified and it is known only to a circle of persons who should have access to a protected area of non-volatile memory. Separating access to the open and closed areas of memory in time and space allows for better preservation of confidential data stored in a hidden non-volatile protected memory, moreover, desoldering of a microcircuit with a public non-volatile memory and subsequent reading of data from it does not allow an intruder to access confidential data.

The device operates for the secret storage of confidential data in non-volatile memory as follows: in the operating mode, a non-volatile public memory is used for all users (Fig. 1 (a)), an authorized user acts in a specially stipulated manner on the detector in order to switch the device to operation with a protected area non-volatile memory, the control system on a chip switches the data transfer control unit to operation with a protected area of non-volatile memory, according to konchaniya read or write data into the protected area of the nonvolatile memory device is switched to the operation mode for all users, the fact of receiving or transmitting data in a nonvolatile memory hidden protected area for storing confidential data not define an unauthorized user.

INFORMATION SOURCES

1. Segmentation for a flash memory of a flash disc. US patent No. 2008/0022034, IPC G06F 12/00.

2. A portable promotional content and interface apparatus. US patent No. 2011/0093395, IPC G06F 21/00.

3. A system, method, and computer program product for nonvolatile memory devices. US patent No. 2006/0288166 Al, IPC G06F 12/00. The priority of the application is 11/21/2005. Published December 21, 2006.

4. Securing temporary data stored in non-volatile memory using volatile memory. US patent No. 2010/0005317 Al, IPC G06F 12/14, H04L 9/06, H04L 9/14. Priority 2.07.2008. Published on January 7, 2010.

5. Microprocessor having secure non-volatile storage access. US patent No. 2009/0292893 Al, IPC G06F 12/14. Priority 10/31/2008. Published on November 26th, 2009.

6. Microprocessor having internal secure memory. US patent No. 2009/0292893 Al, IPC G06F 12/14, G06F 12/00. Priority 10/31/2008. Published on November 26th, 2009.

7. Secure non-volatile memory device and method of protecting data therein. US patent No. 7907447, IPC G11C 11/34. The priority of the application is 7.01.2010. Published 03/15/2011.

8. Universal Serial Bus Specification Revision 3.0: 3.1. September 9, 2011.p.41 (3-1). Retrieved October 14, 2011.

Claims (5)

1. A method of storing confidential data in non-volatile memory, which uses at least two non-volatile memory, one of which is a hidden area for storing sensitive data and is physically separated from the memory for general use (made in the form of a separate crystal in a separate case or in caseless design), characterized in that access to the hidden memory area for storing confidential data under no circumstances can be carried out simultaneously with access mentioning the open memory area for general use, and, conversely, access to the open memory area at a given time excludes the possibility of accessing the closed memory area, and to switch the access mode, a targeted physical effect is used on the detector, which is part of the device that implements the described method, known to a limited circle of people for whom data written in a hidden protected area of non-volatile memory intended for storing confidential data is intended, etc. why, at least one protected area of non-volatile memory should be made as a functional block of a chip-based system, which, in addition, monitors the detector (effects monitoring) and switches data transmission modes in case of detecting the correct effect and which communicates with an external computing medium through a serial data interface, and depending on the type of detector used (operating continuously or only when connecting the device Islands to the external serial bus) device is powered via the serial interface or operates autonomously from the battery, is part of the device. 2. The method according to claim 1, characterized in that the detector is an external software application operating at the operating system level, with which the user is authorized, and which, if successful during authorization, will send a signal to switch the device to operating mode with protected hidden non-volatile memory. 3. The method according to claim 1, in which the detector uses a photosensor that responds to a predefined sequence of light pulses, a temperature sensor that responds to a predetermined temperature, a humidity sensor that responds to a predetermined humidity, a microphone that responds to a predefined sequence of acoustic effects, an accelerometer that responds to a predefined projection of apparent acceleration, a gyroscope that responds to predefined divided measurement of the orientation angle of the device, or any combination thereof. 4. The method according to claim 1, in which at least one area of hidden non-volatile memory for storing confidential data is encrypted by one of the encryption algorithms certified in the Russian Federation. 5. The method according to claim 2, in which the number of failed authorization attempts is more than 1 but less than 5, the program sends a signal to the device to clear the protected area of non-volatile memory.