KR100857760B1 - A method and device to store secret key in flash memory - Google Patents

Abstract

An apparatus for storing an encryption key by using a flash memory and a security method thereof are provided to prevent external hacking or intrusion to other product of the same product group though information on one security key is exposed. A security method of an apparatus for storing an encryption key by using a flash memory includes the following several steps. If a security & storage device is turned on, an FTL(Flash Translation Layer) program is executed(S10). Structural properties of a NAND flash memory like positions, addresses and the number of bad blocks are searched(S11). A security engine generates an address of an encryption key by using the information on the bad block from an encryption algorithm(S12). The encryption key is programmed at the first flash memory according to the generated address of the encryption key(S13). The second flash memory stores the address of the generated encryption key(S14).

Description

A method and device to store secret key in flash memory}

1 is a block diagram illustrating a secure flash memory device of the present invention;

2 is a block diagram illustrating an example in which an encryption key is stored in a secure flash memory device of the present invention;

3 is a flow chart showing one embodiment of a method for storing an encryption key in a secure flash storage device in accordance with the present invention;

4 is a flowchart illustrating a method of reading a stored encryption key according to the embodiment of FIG. 3;

5 is a flow chart showing another embodiment of a method for storing an encryption key in a secure flash storage device according to the present invention;

6 is a flowchart illustrating a method of reading a stored encryption key according to the embodiment of FIG. 5;

* Description of the symbols for the main parts of the drawings *

100: host

120: secure flash memory device

200: host interface

220: CPU

240: security engine

260: first flash memory

280: flash controller

300: main memory

320: second flash memory

400: encryption key storage space

420 code area

440: encryption key and garbage data

The present invention relates to a semiconductor memory device, and more particularly, to a storage method capable of securely storing an encryption key in a flash memory, and a flash memory system using the same.

In general, due to the development of the Internet, the conventional contents (contents) are converted into a digital form, making piracy easier. Therefore, the technical necessity for preventing the rights of copyright holders to be infringed has been increased, and new security technologies corresponding thereto have been developed. Digital Rights Management (DRM) means digital rights management. DRM is a technology that secures the interests of digital content providers, prevents illegal copying, and supports the creation, distribution, and management of contents such as charging royalties and settlement services. This includes digital rights management technology that ensures that only legitimate users use content and pay the appropriate fees, software and security technologies for copyright approval and enforcement, and payment and payment technology. For this reason, the importance of devices for securely storing and managing important rights or information is increasing. This specification is intended to describe an apparatus for securely storing data to be protected.

A secure storage system stores data in a specific area of non-volatile memory in response to a write request from a host. Alternatively, the secure storage device 120 transmits data stored therein to the host in response to a read request from the host. In this case, an encryption key is required for secure data transfer between the host and the secure storage system. The encryption key must be secured from attacks or hacks from external unspecified users and the security of the entire system depends on how and where the encryption key is stored.

In the related art, the encryption key is stored in a nonvolatile semiconductor memory provided in the secure storage device. The encryption keys were stored in the nonvolatile semiconductor memory inside the secure storage device in a batch and regular order during the mass production stage of the product. There is a problem that security keys with a batch and regular order can be easily exposed to external hacking or intrusion. In addition, if one security key information is obtained, another product having the same security key may be easily attacked.

The present invention has been proposed to solve the above problems, and an object of the present invention is to provide a method and apparatus for increasing the security of the secure storage device by storing the encryption key in a different location for each product.

In order to achieve the above object, the encryption key storage method of the present invention includes: searching and collecting bad block information of the flash memory; Generating an encryption key address in which the encryption key is stored using the bad block information; And programming the encryption key into the flash memory according to the encryption key address.

In a preferred embodiment, the flash memory comprises a first flash memory and a second flash memory.

In a preferred embodiment, the first flash memory is a NOR flash memory.

In a preferred embodiment, the second flash memory is NAND flash memory.

In an exemplary embodiment, the encryption key address is an address for storing the encryption key in the first flash memory.

In a preferred embodiment, the bad block information includes information on the bad block address or the number of bad blocks of the second flash memory.

In an exemplary embodiment, the encryption key address is randomized data generated by a security engine through an encryption algorithm with reference to the bad block information.

In a preferred embodiment, the method further comprises storing the encryption key address in the flash memory.

In order to achieve the above object, the secure flash memory system of the present invention includes a first flash memory in which an encryption key is stored; A second flash memory including a plurality of bad blocks; A security engine generating an encryption key address in which the encryption key is stored by referring to bad block information of the second flash memory; And a central processing unit searching for the second flash memory to provide the bad block information to the security engine, and to control the first flash memory and the second flash memory to store the encryption key according to the encryption key address. It includes.

In a preferred embodiment, the first flash memory is a NOR flash memory.

In a preferred embodiment, the second flash memory is NAND flash memory.

In a preferred embodiment, the bad block information includes information on the bad block address or the number of bad blocks of the second flash memory.

In a preferred embodiment, the encryption key address is generated in accordance with any one of encryption algorithms such as Data Encryption Standard (DES), Rivest-Shamir-Adleman (RSA), and Advanced Encryption Standard (AES) in the security engine. .

In a preferred embodiment, the encryption key is stored in the first flash memory.

In a preferred embodiment, the cryptographic key address is stored in a second flash memory.

In a preferred embodiment, further comprising a flash controller for interfacing with the second flash memory.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. do. For a preferable description, it will be described using a Secure MMC (Multi Media Card) device.

1 is a block diagram showing a preferred configuration of the present invention. Referring to FIG. 1, the host 100 includes a device such as a computer device, a portable telephone, a digital camera, and the like. The host 100 synchronizes the protocol with the secure storage device 120 and then initiates communication via the mutual interface. The protocol used between the host 100 and the secure storage device depends on its application purpose, such as SD, MMC card, hard disk (HDD), USB, SATA, and PATA.

The secure storage device 120 may include a host interface 200, a CPU 220, a security engine 240, a first flash memory 260, a flash controller 280, and a main memory 300 to drive the secure storage device. ) And the second flash memory 320.

The host interface 200 matches a protocol for communication between the secure storage device 120 and the host 100 in response to a request from the host 100.

In response to a request from the host 100, the CPU 220 may drive each block (eg, the host interface 200, the first flash memory 260, and the main memory) to drive the secure storage device 120. 300, the security engine 240, the flash controller 280, and the second flash memory 320. The CPU 220 controls to collect bad block information of the flash memory when the FTL (hereinafter referred to as FTL) software of the main memory 300 is driven.

The security engine 240 encrypts or decrypts data provided under the control of the CPU 220. Generally, Data Encryption Standard (DES) encrypts data using a private key, Rivest-Shamir-Adleman (RSA) as a commonly used encryption algorithm, and Advanced Encryption Standard (AES), a US standard encryption algorithm. Optionally run the algorithm. The bad block information of the second flash memory 320 provided according to the FTL is generated by the security engine 240 as an encryption key address having a random address according to the following equation.

The bad block address of the second flash memory 320 is generated as an encryption key address for storing the encryption key through an encryption key address generation algorithm driven by the security engine 240.

The first flash memory 260 stores data provided from the host 100. The first flash memory 260 may be configured as a NOR flash memory in the present invention, and has a space for storing an encryption key. The encryption key is stored mixed with garbage data.

The flash controller 280 performs a control operation for exchanging data with the second flash memory 320.

The main memory 300 stores information for operating the secure storage device 120 such as a code or an address mapping table, an FTL program, firmware, or the like. The main memory 300 is composed of SRAM and DRAM, which are volatile memories. The main memory 300 receives the encryption key read from the first flash memory 260 and temporarily stores the encryption key.

The second flash memory 320 stores an encryption key address and general data in response to a read / write request of the host 100. The second flash memory 320 may be configured as a NAND flash memory in the present invention, and stores the encryption key address generated from the R _Add function in the second flash memory 320.

In summary, the secure storage device 120 collects bad block information, which is a unique characteristic of the flash memory, according to the FTL program. An encryption key address is generated from the function R _Add of the security engine 240 according to the collected bad block information. The encryption key is stored in a specific area of the first flash memory 260 according to the encryption key address generated from the R _Add function. Garbage data is stored in the remaining space of the first flash memory 260 in which the encryption key is not stored.

2 is a block diagram illustrating a data area of the first flash memory 260 according to the present invention. Referring to FIG. 2, the first flash memory 260 includes an encryption key storage space 400 and a code area 420. The encryption key storage space 400 includes an encryption key storage area consisting of an encryption key and garbage. For example, assuming that there are three encryption key addresses generated from the R _Add function, as shown in FIG. 2, the encryption key "Key 0" corresponds to the encryption key address randomly generated from the function R_Add, and the address "1". "Is stored in the area corresponding to the times. The encryption key "Key 1" is located at address "5" corresponding to the encryption key address randomly generated from the function R _Add . The encryption key "Key M" is stored at address "N" corresponding to the encryption key address randomly generated from the function R _Add . Garbage data is input to the remaining addresses. The random cryptographic key address generated from the R _Add function of the security engine 240 is batch and non-regular. For this reason, if the bad block information having different characteristics for each product is used, encryption keys are stored at different addresses for each product, thereby improving security. The number of encryption keys can be changed according to the purpose of product development.

Code area 420 stores code or firmware software for driving secure storage device 120.

3 is a flowchart showing one embodiment of the present invention. The secure storage device 120 requires additional software called disk emulation software for compatibility with the host 100. During the communication operation, compatibility between the host 100 and the secure storage device 120 may be achieved by operating an embedded system such as a flash translation layer. In other words, the host 100 recognizes the secure storage device 120 as a hard disk and connects the same in the same manner as the hard disk. Referring to FIG. 3, when power is applied to the secure storage device 120, an FTL program is executed (S10). When the FTL program is executed, bad block information such as the location, address, and number of bad blocks, which are structural characteristics of the NAND flash memory, is retrieved (S11). The retrieved bad block information is transmitted to the security engine 240. The security engine 240 generates an encryption key address using bad block information from an encryption algorithm (for example, Rivest-Shamir-Adleman (RSA)) (S12). The encryption key is programmed in the first flash memory 260 according to the encryption key address generated by the encryption algorithm (S13). In operation S14, an encryption key address generated by an encryption algorithm is stored in the second flash memory 320. Due to the characteristics of the flash memory, the encryption key address programmed in the second flash 320 is maintained without being deleted even when the secure storage device 120 is powered off.

4 is a flowchart showing an example of driving a SecureMMC card according to the embodiment of FIG. 4 is implemented in a real user environment. When power is applied to the secure storage device 120 from the outside, the FTL program is executed (S20). The encryption key address is read from the second flash 320 and loaded into the main memory 300 (S21). The encryption key stored in the first flash memory 260 is read according to the read encryption key address (S22). After verifying the encryption key according to the encryption key read from the main memory 300, the secure storage device 120 is driven (S23).

5 is a flowchart illustrating another embodiment of a method for storing an encryption key in a secure flash storage device according to the present invention. Referring to FIG. 5, when power is applied to the secure storage device 120, an FTL program is executed (S30). When the FTL program is executed, bad block information such as the location, address, and number of bad blocks, which are structural characteristics of the NAND flash memory, is retrieved (S31). The retrieved bad block information is transmitted to the security engine 240. The bad block information transmitted to the security engine 240 is generated as an encryption key address by an encryption algorithm (for example, Rivest-Shamir-Adleman (RSA)) (S32). The encryption key is programmed in the first flash memory 260 according to the encryption key address (S33). Unlike the first embodiment described in FIG. 3, according to the second embodiment of the present invention, the encryption key address generated by the encryption algorithm is not stored in the second flash memory 320. Therefore, when the power of the secure storage device 120 is cut off, the encryption key address information existing on the main memory 300 is deleted.

6 is a flowchart showing an example of driving a SecureMMC card according to the embodiment of FIG. 6 is implemented in a real user environment. When power is applied to the secure storage device 120, the FTL program is executed (S40). When the FTL program is executed, bad block information such as the location, address, and number of bad blocks, which are structural characteristics of the NAND flash memory, is retrieved (S41). The retrieved bad block information is transmitted to the security engine 240 for encryption. The bad block information transmitted to the security engine 240 is generated as an encryption key address by an encryption algorithm (for example, Rivest-Shamir-Adleman (RSA)) (S42). The encryption key is read from the first flash memory 260 according to the encryption key address (S43). The secure storage device 120 is driven according to the encryption key read from the first flash memory (S44).

In summary, according to the first embodiment described, the encryption key address generated with the bad block information is programmed in the second flash memory 320. Therefore, even if the power of the secure storage device 120 is cut off, the stored encryption key address is not deleted. On the other hand, according to the second embodiment described with reference to FIGS. 5 and 6, the encryption key address generated with the bad block information is driven on the main memory 300 without being stored in the second flash memory 320. When the power of the secure storage device 120 is cut off, the stored encryption key address is deleted and generates an encryption key address whenever power is applied to the secure storage device 120.

On the other hand, in the detailed description of the present invention has been described with respect to specific embodiments, various modifications are of course possible without departing from the scope of the invention. Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be defined by the equivalents of the claims of the present invention as well as the following claims.

As described above, the address of the encryption key is generated using bad block information, which is a structural characteristic of the NAND flash memory. Using bad block information as an encryption key address, the encryption key is programmed at a random location in memory. Therefore, it is hard to be easily exposed to external hacking or intrusion. Also, even if one piece of security key information is acquired, it is difficult to be hacked into other products of the same product family.

Claims (16)

A method for storing encryption keys in a memory system: Retrieving the number or location information of the bad blocks of the first memory device; And Generating an encryption key address in a second memory device for storing the encryption key with reference to the number or location information of the bad blocks; And the encryption key address is generated as data randomized through an encryption algorithm from the number or location information of the bad blocks. The method of claim 1, And writing the encryption key to the second memory device according to the encryption key address. The method of claim 2, And the encryption key is discontinuously stored in a plurality of areas of the second memory device according to the encryption key address. The method of claim 3, wherein And in the second memory device, garbage data is written in memory areas corresponding to the plurality of discrete areas. The method of claim 1, And the first memory device is a NAND flash memory device. The method of claim 5, wherein And the second memory device is a NOR flash memory device. The method of claim 1, And storing the encryption key address in the first memory device or the second memory device. delete A first flash memory in which an encryption key is stored; A second flash memory including a plurality of bad blocks; A security engine generating an encryption key address in which the encryption key is stored by referring to bad block information of the second flash memory; And A central processing unit for searching the second flash memory to provide the bad block information to the security engine, and to control the first flash memory and the second flash memory to store the encryption key according to the encryption key address. Including a secure flash memory system. The method of claim 9, And the first flash memory is a NOR flash memory. The method of claim 10, And said second flash memory is a NAND flash memory. The method of claim 11, The bad block information includes information on the bad block address or the number of bad blocks of the second flash memory. The method of claim 9, The encryption key address is generated by the security engine according to any one of encryption algorithms such as Data Encryption Standard (DES), Rivest-Shamir-Adleman (RSA), and Advanced Encryption Standard (AES). The method of claim 9, And the encryption key is stored in a first flash memory. The method of claim 14, And the encryption key address is stored in a second flash memory. The method of claim 9, And a flash controller for interfacing with the second flash memory.

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