JP2013186911A - Device unique information generation device and device unique information generation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate unique information in a short period of time in the case of generating the unique information of a device on the basis of a measurement object that is easily fluctuated by the temperature of the device.SOLUTION: Refresh stop time determination means for performing test processing for stopping refresh only for a test time, and determining a refresh stop time corresponding to the assumed number of inversion bits being the number of inversion bits needed to generate unique information on the basis of the number of test processing inversion bits being the number of inversion bits caused by the test processing, and unique information generation means for generating information on the basis of information on inversion bits acquired by a refresh stop with the determined refresh stop time applied thereto are provided.

Description

  The present invention relates to a device specific information generation apparatus and a device specific information generation method for generating device specific information, and in particular, a device specific information generation apparatus that generates device specific information using a physical state inside the device, and The present invention relates to a device specific information generation method.

  With regard to information security, in order to realize a safe information / communication system, in the communication between the server and the terminal device, an authentication process for determining whether or not the other party is a legitimate party is necessary. The authentication process is premised on the presence of device-specific information (ID). The serial number is a representative example, but it is easy for an attacker who has obtained a legitimate device to obtain this serial number. Also, based on the serial number of one device, the serial number of another device can also be obtained. There are many things that can be guessed. If a terminal device has a random secret key, it is difficult to guess the secret key of another device based on the secret key of a certain device, but its holding method becomes a problem. In the method of keeping confidential information in a memory (for example, ROM (Read Only Memory)), there is a problem that an unauthorized device can be duplicated if the attacker can copy the memory as it is without analyzing the contents. . In the conventional tamper resistant technology that copes with such an attack, for example, a method of having secret information in a volatile memory is adopted, and there is a problem that the cost becomes high because a battery for holding data is required.

  In recent years, as a method to realize device authentication, research on a method for generating device specific information and using it for authentication using physical variations inevitably occurring in the manufacturing process etc. It is called “Physically Unclonable Function (PUF)”.

  FIG. 1 shows a configuration diagram of a unique information generation unit 110 based on PUF and an authentication system using the same. Authentication is performed between the terminal device 150 and the server 160. The authentication unit 100 in the terminal device 150 includes a unique information generation unit 110 and an interface 140.

  The unique information generation unit 110 includes a device physical information generation unit 120 and a physical information mapping unit 130.

  The device physical information generation unit 120 normally uses a device that originally exists as a component of the terminal device.

  The physical information mapping unit 130 converts the information obtained by the device physical information generation unit 120 as necessary to generate device specific information.

  The interface 140 performs an interface process with the server 160, and executes encryption and an authentication algorithm using the device specific information as secret information as necessary.

  Non-Patent Document 1 below discloses a method that uses the randomness of wiring delay that inevitably occurs in the manufacturing process.

  The method using Static Random Access Memory (SRAM) utilizes the fact that the initial value of each bit when the SRAM is powered on is random. This is disclosed, for example, in Non-Patent Document 2 below.

  At this time, the input information to the device physical information generation unit 120 shown in FIG. 1 is the position of all bits whose value is 1 in a predetermined area of the SRAM. At this time, the physical information mapping unit 130 simply outputs the initial value at the time of power-on of the bit position having a value of 1 given as input information. In the initial setting phase of device terminal authentication, as an initial setting process, an initial value at the time of power-on of this bit position is generated in advance by the terminal device and registered in the server. In the authentication phase, the server receives the initial value at power-on of the bit position generated at that time by the terminal device, and this is the initial value at power-on of the bit position registered in the initial setting phase. To match.

  Patent Document 1 describes that unique information can be generated not only for SRAM but also for Dynamic Random Access Memory (DRAM) by the same method. A DRAM expresses a bit having a value of 0 or 1 depending on the presence or absence of charge in a capacitor constituting the element. Over time, due to leakage current, the charge accumulated in the capacitor disappears, so the DRAM periodically reads out, and based on the read value, the refresh process to recharge the capacitor is performed. Required. It is considered that the charge dissipation rate of each element has a variation that is difficult to predict. This characteristic can be used for generating unique information.

  In the authentication of the terminal device using the device specific information generated by the DRAM, the following is performed. A bit that is inverted from the charge retention bit value (typically “1”) after the refresh process is stopped for a certain period of time as an initial setting process (hereinafter simply referred to as “inverted bit”) (a bit that is inverted when the refresh is stopped) Is registered in advance in the server. Similarly, at the time of authentication, the server receives the position of the bit that is inverted by the refresh stop that is performed again, and performs authentication by checking this with the bit position registered in the initial setting.

  In such device specific information generation using a DRAM, since the amount of output information can be suppressed by the amount of information of the inverted bit at an early stage, authentication is not performed using information relating to the position of the inverted bit directly. In general, the information is used as a secret key for encryption or hash function. When the position information of the inverted bit is used as a secret key, it is usually necessary to process two types of phases, an initial setting phase and a key generation phase.

  In the DRAM PUF, in the initial setting phase, a certain number of bits that are inverted at an early stage are specified, and a secret key is determined based on position information (index) of the inverted bits. The key generation phase is executed when the secret key is used. The refresh process is stopped, the initial inverted bit is obtained, the initial inverted bit is estimated, and the secret key is generated. In the secret key generation phase, inverted bits other than the inverted bits of the initial setting phase are obtained, and the inverted bits other than the inverted bits of the initial setting phase become noise. In order to stably generate a secret key against such noise, an error correction code is used. As an application method thereof, for example, a scheme called Fuzzy vault is known. Fuzzy vault is shown in Non-Patent Document 3 below.

Special table 2009-533741

G. E. Shu and S. Devadas, “Physically Unclonable Functions for Device Generation and Secret Key Generation,” Proc. 44th Design Automation Conference, pp.9-14. Daniel E. Holcomb, Wayne P. Burleson, and Kevin Fu, “Power-Up SRAM State as an Identifying Fingerprint and Source of True Random Numbers,” IEEE Trans. Computers, vol.58, no.9, pp.1198-1210 , 2009. A. Juels and M. Sudan, “A Fuzzy Vault Scheme”, International Symposium on Information Theory, p.408, 2002

  The charge retention characteristics of each element of the DRAM are greatly affected by temperature. The refresh stop time for determining the first constant or a fixed number of inversion bits varies greatly depending on the temperature. Even when it is desired to increase the number of inversion bits, the charge is charged by the reading process. Therefore, in order to increase the number of inversion bits, it is necessary to retry the refresh stop process from the beginning. A case where the retry is repeated several times is assumed, and the execution time also increases at this time. In order to shorten the execution time of generating unique information using a DRAM, it is necessary to set an appropriate refresh process stop time according to the temperature.

  Therefore, the present invention provides a device specific information generation apparatus and device that can generate specific information in a short time when generating specific information of the device based on a measurement target that is likely to vary depending on the temperature of the device. An object is to provide a unique information generation method.

  According to the present invention, a device unique information generating apparatus for generating device unique information, which performs a test process for stopping refresh for a test time, and is a test process inversion bit that is the number of inversion bits generated by the test process A refresh stop time determining means for determining a refresh stop time corresponding to an assumed inversion bit number that is the number of inversion bits necessary for generating the unique information based on the number, and the determined refresh stop time There is provided a device specific information generation device comprising: specific information generation means for generating the specific information based on information relating to the inverted bit obtained by the applied refresh stop.

  Further, according to the present invention, there is provided a device specific information generation method for generating device specific information, wherein a test process for stopping refresh for a test time is performed, and a test process that is the number of inverted bits generated by the test process A refresh stop time determining step for determining a refresh stop time corresponding to an assumed inversion bit number that is an inversion bit number necessary for generating the unique information based on the inversion bit number; and the determined refresh stop And a unique information generating step for generating the unique information on the basis of information on the inverted bit obtained by the refresh stop applying time.

  Furthermore, according to the present invention, there is provided a device specific information generation program for causing a computer to function as a device specific information generation apparatus for generating device specific information, wherein the computer is stopped for refreshing only for a test time. Based on the inversion bit number that is the number of inversion bits generated by the test process, the refresh stop corresponding to the assumed inversion bit number that is the inversion bit number necessary for generating the unique information is performed. A refresh stop time determining means for determining a time, and a unique information generating means for generating the unique information based on information relating to an inverted bit obtained by a refresh stop applying the determined refresh stop time. A device specific information generation program is provided.

  According to the present invention, it is possible to generate unique information in a short time when generating unique information that easily varies depending on the temperature of the device.

It is a block diagram of a general apparatus specific information generation method. It is a block diagram showing the structure of the device specific information generation apparatus by embodiment of this invention. It is a figure showing the structure of the refresh stop time table by embodiment of this invention. It is a flowchart for demonstrating the process of the initial setting phase contained in the device specific information generation method performed by the device specific information generation apparatus by embodiment of this invention. It is a flowchart for demonstrating the process of the key generation phase contained in the device specific information generation method performed by the device specific information generation apparatus by embodiment of this invention. It is an example of the refresh stop time table by embodiment of this invention. It is a block diagram which shows the structure of the principal part of the device specific information generation apparatus by embodiment of this invention. It is a graph which shows the example of an experiment of refresh processing stop time and the number of inversion bits in DRAM.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 2 illustrates an embodiment of the present invention. A device physical information generation unit 200 corresponding to the device physical information generation unit 120 of FIG. 1 includes a DRAM device 210, an R / W controller (Read / Write Controller) 220. , A refresh processing control unit 230. The refresh processing control unit 230 includes a refresh stop time table 240 as a component.

  The R / W controller 220 performs reading (Read) and writing (Write) of data with respect to the DRAM device 210. A device including the DRAM device 210 and the R / W controller 220 (including a refresh process) has a normal DRAM configuration.

  The refresh process control unit 230 controls the R / W controller 220 to control a refresh process stop time when the DRAM device 210 is used for generating unique information.

  The physical information mapping unit 250 corresponds to the physical information mapping unit 130 of FIG. 1, identifies the inverted bit generated when the refresh process is stopped, and uses the inverted bit position information (index) as device-specific information. A process for generating a bit string to be used is performed. When used for secret key generation, in the initial setting phase, the inversion bit generated by the refresh stop process is specified, and based on the inversion bit position information, redundant data necessary for error correction in the key generation phase ( (referred to as helper data). In the key generation phase, in addition to the inverted bit position information obtained by the refresh stop process executed in the key generation phase, a process for generating a secret key using the redundant data generated in the initial setting phase is executed. .

  FIG. 3 shows an example of the configuration of the refresh stop time table 240 in the embodiment of the present invention.

  The column of “test process inversion bit number” in the second column from the left end shows an estimate of the inversion bit number generated by the test process for stopping the refresh process for a predetermined time at each temperature. This fixed time is referred to as “test refresh stop time”.

  The column of “initial setting phase refresh stop time” in the third column from the left end indicates the refresh stop time in the initial setting phase at each temperature. The refresh stop time also depends on the number of inverted bits assumed in the initial setting phase. That is, in the initial setting phase, the refresh stop time at each temperature for obtaining a constant number of inversion bits (hereinafter referred to as “assumed inversion bit number”) is the “initial setting phase refresh stop time”.

  A column of “key generation phase refresh stop time” over four columns from the fourth column to the right end column from the right end indicates a refresh stop time in the key generation phase. This refresh stop time depends on a set of temperature at the time of execution of the initial setting phase and temperature at the time of execution of the key generation phase.

  In general, the greater the temperature difference between the initialization phase temperature and the key generation phase temperature, the more inverted bits are required in the key generation phase. Therefore, not only the temperature at the time of executing the key generation phase but also the temperature at the time of executing the initial setting phase is an element for determining the refresh processing stop time in the key generation phase. For this reason, the refresh stop time in the key generation phase is set not only according to the temperature during execution of the key generation phase but also according to the temperature during execution of the initial setting phase.

  It is assumed that the temperature during execution of the initial setting phase is equal to the temperature during execution of the test process immediately before, and the temperature during execution of the key setting phase is equal to the temperature during execution of the test process immediately before.

  In FIG. 3, the number of inverted bits in the initial setting phase is n3 as indicated by reference numeral 301. Based on this, when it is estimated that the temperature during execution of the initial setting phase is T3, that is, in the initial setting phase. When the number of inverted bits of the test processing in n is n3, the use of any cell included in the column corresponding to T3 corresponding to n3 is indicated by an ellipse denoted by reference numeral 302 in the key generation phase. Therefore, n1 obtained in the initial setting phase is stored until the key generation phase.

  In the key generation phase, the number of inverted bits obtained by the test process in the initial setting phase determines the column, the number of inverted bits obtained by the test process in the key generation phase determines the row, and the determined column The time in the cell specified in (1) is used as the refresh stop time in the key generation phase.

  The refresh stop time table 240 is typically generated in advance from a device sample.

  FIG. 4 shows a flow of steps included in the initial setting phase of the device specific information generation method performed by the device specific information generation apparatus according to the embodiment of the present invention.

  The R / W controller 220 executes a charge process for all bits in the unique information generation area in the DRAM (step 420). Typically this is done by writing '1' to all bits.

  The refresh control unit 230 stops the refresh process for the test refresh stop time (step 430). Here, the test refresh stop time is determined in advance.

  After the refresh process is stopped in step 430, the R / W controller 220 reads the bit value in the unique information generation area (step 440).

  The refresh control unit 230 obtains the number of inverted bits (the number of inverted bits) based on each bit value read in step 440 (the number of inverted bits) and uses the inverted bits for later use in the key generation phase. The number is held as “initial setting phase test process inversion bit number”. Then, based on the number of inverted bits of the initial setting phase test process, the refresh stop time table 240 is used to determine the refresh stop time for the initial setting phase (hereinafter referred to as “initial setting phase refresh stop time”) ( Step 450). In other words, the refresh stop time table 240 is searched for a row in which the “test processing inversion bit number” in the second column from the left end is closest to the initial setting phase test inversion bit number obtained by the actual test refresh stop processing, The “initial setting phase refresh stop time” in the third column from the left end is set as the determined initial setting phase refresh stop time. Here, the “current temperature” in the leftmost column of the row is the initial setting phase temperature. In principle, the initial setting phase temperature is estimated from the “initial setting phase test process inversion bit number”, and the “initial setting phase refresh stop time” corresponding to the estimated initial setting phase temperature is determined. In the refresh stop time table 240, the “test process inversion bit number in the second column from the left that is closest to the initial set phase test inversion bit number obtained by actual test processing is calculated. "Initial setting phase refresh stop time" corresponding to "" is obtained.

  Next, the R / W controller 220 returns all the bits to the initial state by executing the charge processing for all the bits in the unique information generation area in the DRAM (step 460).

  The refresh control unit 230 stops the refresh process for the "initial setting phase refresh stop time" determined in step 450 (step 470).

  After stopping the refresh process in step 470, the R / W controller 220 reads the bit value of each bit in the unique information generation area (step 480).

  Using the inverted bit position information (index) obtained in step 480, the physical information mapping unit 130 determines specific information and generates redundant data (called helper data) necessary for error correction in the key generation phase. (Step 490).

  FIG. 5 shows a flow of steps included in the key generation setting phase of the device specific information generation method performed by the device specific information generation apparatus according to the embodiment of the present invention.

  The test processing in steps 520 to 540 is the same as that in steps 420 to 440 in the initial setting phase.

  The R / W controller 220 executes charge processing for all bits in the unique information generation area in the DRAM (step 520). Typically this is done by writing '1' to all bits.

  The refresh controller 230 stops the refresh process for the test refresh stop time (step 530).

  After stopping the refresh process in step 530, the R / W controller 220 reads the bit value in the unique information generation area (step 540).

  The refresh control unit 230 obtains the number of inverted bits (the number of inverted bits) based on each bit value read in step 540 (the number of inverted bits), and the inverted number of bits is “inverted key generation phase test process”. Holds as "number of bits". Then, the refresh control unit 230 estimates the current temperature as the temperature at the time of executing the key generation phase from the key generation phase test process inversion bit number. Then, based on the initial setting phase test process inversion bit number and the key generation phase test process inversion bit number, the refresh stop time table 240 is used to perform a refresh stop time (hereinafter referred to as “key generation phase refresh stop”). Time ") is determined (step 550).

  Specifically, in step 550, the “test process inversion bit number” in the second column from the left end of the table is the row closest to the initial set phase test inversion bit number obtained by the actual key generation phase test refresh stop process. Is searched from the refresh stop time table 240, and the “current temperature” in the leftmost column of the row is obtained as the key generation phase temperature. Of the plurality of columns of “key generation phase refresh stop time” provided for each initial setting phase temperature in the refresh stop time table 240, the initial setting phase temperature that is the same as the initial setting phase temperature obtained in the initial setting phase. A column is a selected column. Then, the row whose “test processing inversion bit number” in the second column from the left end is closest to the key generation phase test processing inversion bit number obtained by the key generation phase test refresh stop processing is selected.

  Then, the “key generation phase refresh stop time” in the cell determined by the combination of the selected column and the selected row in the refresh stop time table 240 is set as the determined key generation phase refresh stop time.

  The process of specifying the inverted bit in steps 560 to 580 is the same as that in the initial setting phase 460 to 480 in FIG.

  The R / W controller 220 initializes all the bits by executing the charge processing for all the bits in the unique information generation area in the DRAM (step 560).

  The refresh control unit 230 stops the refresh process for the “key generation phase refresh stop time” determined in step 550 (step 570).

  After the refresh process is stopped in step 570, the R / W controller 220 reads the bit value of each bit in the unique information generation area (step 580).

  Using the inverted bit position information (index) obtained in step 580 and the helper data obtained and held in step 490, the physical information mapping unit 130 uses the inverted bit position information (index) in step 490. And secret information is generated by estimating the unique information (step 590).

  If the number of inversion bits in the initial setting phase test process is equal to the assumed inversion bit number, steps 460 to 480 are omitted, and the inversion bit position information obtained by reading in step 440 is replaced with the inversion bit position information obtained in step 480. May be used.

  Similarly, if the key generation phase test process inversion bit number is equal to the assumed inversion bit number, steps 560 to 580 are omitted, and the inversion bit position information obtained by reading in step 540 is the inversion bit position information obtained in step 580. It may be used instead of.

  This can be determined by writing not only the refresh stop time but also the assumed number of inversion bits in the column corresponding to the key generation phase of the refresh stop time table 240. In FIG. 6, the number of inverted bits is represented by a number enclosed in parentheses.

  If it is determined that the number of inversion bits obtained from the inversion bit position information obtained in step 480 is not equal to the assumed inversion bit number, the initial setting phase refresh stop time is corrected and the processing from step 460 is performed. repeat. The extent to which the initial phase refresh stop time is corrected in the correction can be determined based on the relationship between the inverted bit number and the initial phase refresh stop time and the difference between the two bit numbers. This repetition is repeated a plurality of times until the difference between the numbers of both inversion bits becomes a predetermined value or less.

  Similarly, if the generation of the secret key fails at 590, the key generation phase refresh stop time is corrected and the processing from step 560 is repeated. The extent to which the key generation phase refresh stop time is corrected in the correction depends on the relationship between the inversion bit number and the key setting phase refresh stop time, the inversion bit number obtained from the inversion bit position information obtained in step 580, and the assumed inversion bit number. Based on the difference between the two. This repetition is repeated until the secret key is successfully generated.

  In step 450, when obtaining the initial setting phase refresh stop time using the refresh stop time table 240 based on the initial setting phase test processing inversion bit number, the “test processing inversion bit closest to the initial setting phase test inversion bit number” is set. Instead of “number”, search for the largest “test processing inversion bit number” that is less than or equal to the initial setting phase test inversion bit number, and find the “initial setting phase refresh stop time” corresponding to the found “test processing inversion bit number” It may be. Alternatively, the smallest “test processing inversion bit number” that is equal to or larger than the initial setting phase test inversion number bit may be searched for, and the “initial setting phase refresh stop time” corresponding to the found “test processing inversion bit number” may be obtained. . Furthermore, the time obtained by linear interpolation using two “initial setting phase refresh stop times” respectively corresponding to two “test processing inverted bit numbers” sandwiching the initial setting phase test inverted bit number is determined and initialized. It may be the phase refresh stop time. Instead of performing linear interpolation, use three or more “test processing inversion bit numbers” in the vicinity of the initial setting phase test inversion bit number and three or more “initial setting phase refresh stop time” corresponding to them. Interpolation may be performed by a method.

  In step 550, when determining the key generation phase refresh stop time using the refresh stop time table 240 based on the initial set phase test process inversion bit number and the key generation phase test process inversion bit number, the initial set phase test inversion bit number Instead of the closest “test process inversion bit number”, the largest “test process inversion bit number” that is less than or equal to the initial phase test inversion bit number is searched, and the column corresponding to the found “test process inversion bit number” is It is good also as a selection column. Further, the smallest “test process inversion bit number” that is equal to or larger than the initial phase test inversion bit number may be searched, and the column corresponding to the found “test process inversion bit number” may be set as the selection column. Furthermore, a column having “test process inversion bit number” having the largest number less than or equal to the key generation phase test inversion bit number may be the selected row, and “test process inversion bit number” may be the key generation phase test inversion bit number. The column having the smallest number as described above may be the selected column. Further, two columns corresponding to two “test process inversion bit numbers” sandwiching the initial setting phase test inversion bit are used as the above-mentioned selected columns, and two “test process inversion bit numbers in between the key generation phase test inversion bit number” are set. Using the two corresponding rows as the above-mentioned selected rows, two-dimensional linear interpolation is performed using the “key generation phase refresh stop time” of four cells determined by the combination of the two selected columns and the two selected rows. The determined key generation phase refresh stop time may be used as the time obtained by performing the above process, and generally two or more columns corresponding to two or more “test processing inversion bit numbers” in the vicinity of the initial set phase test inversion bit number, respectively. As a selection column, two or more corresponding to the “test processing inversion bit number” of two or more near the key generation phase test inversion bit number. As a selected row, using a “key generation phase refresh stop time” of four or more cells determined by a combination of two or more selected columns and two or more selected columns, and two-dimensionally by various methods. Note that the domain of the interpolation is two-dimensional, that is, the initial setting phase test process inversion bit number × the key generation phase test process inversion bit number, and the value range is the key generation phase refresh stop time.

  The refresh stop time table 240 is typically generated in advance from a device sample, but the refresh stop time table is determined based on the number of inversion bits in step 590 and the state of the estimation process in step 590 of the unique information of the initial setting phase. It is also conceivable to correct the refresh stop time written in 240. That is, if the actual inversion bit number is larger than the assumed inversion bit number, the refresh stop time can be corrected and overwritten.

  As described above, the generation time of the unique information using the DRAM becomes long when the temperature is low and the bit inversion time becomes long. Especially when the initialization phase is performed at a high temperature and the key generation phase is performed at a low temperature, it is necessary to obtain the same number of inversion bits as the number of inversion bits in the initialization phase at a low temperature. Execution time is particularly large.

  On the other hand, a method of changing the redundancy of error correction coding according to the estimated temperature in step 450 of the initial setting can be considered. In other words, if it is determined in step 450 that the temperature is high, the redundancy can be increased to increase the error correction capability, so that the decryption process (error correction process) can be performed with a small number of inverted bits in the key generation phase at a low temperature. To be.

  In step 540 of the key generation phase, when the obtained number of inversion bits of the key generation phase test process is small, and it is determined that the current temperature is low, immediately or after performing step 590, the assumption is made. It is also conceivable to reduce the number of inversion bits and reduce the initial setting phase refresh stop time accordingly, and redo the initial setting phase. As a result, even when the key generation phase is performed at a low temperature, the key generation process can be successfully performed without increasing the key generation phase refresh stop time.

  In this embodiment, in both the initial setting phase and the key generation phase, a refresh stop time table showing the relationship between the temperature and the refresh stop time for obtaining the assumed number of inversion bits is prepared, and the test refresh stop in the test process is performed. Inverted bit obtained by estimating the current temperature based on the number of inversion bits corresponding to time, selecting an appropriate refresh stop time at the current temperature from the refresh stop time table, and stopping the refresh for that refresh stop time Since the number can be made approximately equal to the assumed number of inversion bits, it is possible to set an appropriate refresh stop time with a small overhead, and therefore, it is possible to reduce the retry of the refresh stop processing, and thus unique information generation Execution time can be reduced To become.

  In addition, by introducing the test process, the temperature sensor becomes unnecessary, and individual differences in the charge disappearance rate can be absorbed and the refresh stop time can be made appropriate.

  Next, the configuration of the main part of the device specific information generation apparatus according to the embodiment of the present invention will be described with reference to FIG.

  Referring to FIG. 7, the main part includes a refresh control unit 230, a physical information mapping unit 250, and an execution control unit 255.

  The refresh control unit 230 includes a refresh stop time determination unit 231, a refresh stop time table 240, and a refresh stop process execution unit 237.

  The refresh stop time determination unit 231 includes a test process execution unit 232, an inversion bit number acquisition unit 233, an initial setting phase test process inversion bit number holding unit 234, an initial setting phase refresh stop time determination unit 235, and a key generation phase refresh stop time determination. Part 236.

  The refresh stop time table 240 includes a first table 241 and a second table 242.

  The physical information mapping unit 250 includes an inverted bit information acquisition unit 251, a redundant data generation / holding unit 252, a specific information generation core unit 253, and a redundancy level changing unit 254.

  Functionally, a specific information generation unit includes a refresh stop process execution unit 237, an inverted bit information acquisition unit 251, a redundant data generation / holding unit 252, a specific information generation core unit 253, and a redundancy change unit 254. 257 is configured.

  The test process execution unit 232 executes a test process in the initial setting phase and a test process in the key generation phase.

  The inverted bit number acquisition unit 233 acquires the number of inverted bits generated by the test process in the initial setting phase and the number of inverted bits generated by the test process in the key generation phase.

  The initial setting phase test process inverted bit number holding unit 234 holds the number of inverted bits generated by the test process in the initial setting phase, which is acquired by the inverted bit number acquisition unit 233.

  The initial setting phase refresh stop time determination unit 235 applies the refresh stop time applied to the initial setting phase based on the number of inversion bits in the initial setting phase acquired by the inversion bit number acquisition unit 233 and the first table 241. To decide.

  The key generation phase refresh stop time determination unit 236 includes the number of inversion bits generated by the test process in the initial setting phase and the inversion bit number acquisition unit 233. The refresh stop time applied to the key generation phase is determined based on the obtained number of inverted bits generated by the test processing in the key generation phase and the second table.

  The refresh stop process execution unit 237 executes the refresh process in the test process and the refresh stop process using the determined refresh stop time.

  The first table 241 holds the correspondence relationship between the number of inverted bits obtained by the initial setting phase test process and the refresh stop time applied to the refresh stop process in the initial setting phase. In the case as shown in FIG. 3, the table shown in FIG. 3 is composed of the second column and the third column from the left.

  The second table 242 includes the number of inverted bits obtained by the initial setting phase test process, the number of inverted bits obtained by the key generation phase test process, and the refresh stop time applied to the refresh stop process of the key generation phase. Specifically, if the entire table is as shown in FIG. 3, the table shown in FIG. 3 is composed of the second column and the fourth to seventh columns from the left. .

  The inverted bit information acquisition unit 251 includes information on the inverted bits obtained by the refresh stop process in the initial setting phase (information about which bits are inverted) and information on the inverted bits obtained by the refresh stop process in the key generation phase. To get.

  The redundant data generation / holding unit 252 generates redundant data of an error correction code for the unique information based on the information about the inverted bit obtained by the refresh process in the initial setting phase acquired by the inverted bit information acquisition unit 251. Hold it.

  The unique information generation core unit 253 generates unique information based on the information related to the inverted bits obtained by the refresh stop process in the key generation phase and the redundant data.

  The execution control unit 255 controls the overall operation of the device specific information generation apparatus. The execution control unit 255 also performs control for re-starting from the initial setting phase when the number of inverted bits generated by the key generation phase test process is equal to or less than a predetermined number.

  An embodiment will be described using experimental results using the same 10 64-Mbit Synchronous DRAM (SDRAM).

  FIG. 8 shows the relationship between the refresh processing stop time and the number of inverted bits for one of the SDRAMs. It can be seen that the number of inversion bits greatly varies depending on the temperature even in the same refresh processing stop time. Assuming that the refresh process stop time of the test process is 5 seconds, the number of inverted bits at −5, 25, 45, and 65 ° C. is about 0, 25, 500, and 7000 in FIG. Conversely, in the test process, the current temperature is estimated from the number of inverted bits in the 5-second refresh stop process. If the above four temperature settings are made in the refresh stop time table and 100 inversion bits are generated in the test process, the temperature is estimated to be between 25 ° C. and 45 ° C. The refresh stop time is calculated as follows.

  With respect to the inversion bit number n obtained by the test process, the adjacent test process inversion bit numbers n1 and n2 in the refresh stop time table are selected so that n1 <n <n2. Let J1 and J2 be refresh stop times in the initial setting phase corresponding to n1 and n2. When linear interpolation is used, the refresh stop time J is set as follows.

[Formula 1] J = (n2-n) / (n2-n1) * J1 + (n-n1) / (n2-n1) * J2
In the above example of n = 100 (n1 = 25, n2 = 500)
J = (500-100) / (500-25) × J1 + (100-25) / (500-25) × J2
= 400/475 x J1 + 75/475 x J2
It becomes.

  Next, a case where the fuzzy vault described in Non-Patent Document 3 is applied as an example of a method for generating a secret key from the position (index) information of the early inversion bit of DRAM will be described. Each bit of DRAM of size q = 2 ^ {L} can be represented by an L-bit index. This index is associated with an element of the Galois field GF (q). Fuzzy vault is specified by four parameters t, r, k, s in addition to L and q.

[Initial setting phase]
a1) t inverted bits a_ {1},..., a_ {t} are determined in steps 420-490 in FIG. Let this set be B1.

  a2) A polynomial f (x) (deg (f) <k) on GF (q) is prepared as secret information.

a3) A set of elements of GF (q) × GF (q), where A = B1
V = {(a_ {1}, f (a_ {1})),…, (a_ {t}, f (a_ {t}))}
Set.

  a4) Repeat the following process from j = t + 1 to r.

a4-1) Random selection of elements a_ {j} of GF (q) that do not belong to A
a4-2) Select c_ {j} at random so that c_ {j} ≠ f (a_ {j}).

a4-3) A ← A ∪ {a_ {j}}, V ← V ∪ {(a_ {j}, c_ {j})}.
a5) Hold V as helper data.

  V in step a5) is called vault, and (a_ {j}, c_ {j}) in step a4-2) is called chaff data.

  The key generation phase is as follows.

[Key generation phase]
b1) Identify s inverted bits a ′ _ {1},..., a ′ _ {s} in steps 520-590.

  b2) Identify a '_ {j} that matches the original first component of V in step a5).

  b3) A decoding process is executed from the elements of V that match in step b2) to estimate f.

  r, k, and t are parameters that determine the amount of information. In step b2), the number matching the element corresponding to B1 is m, and the number matching the element corresponding to other than B1 is e. In step b3), f can be correctly estimated when m ≧ k and e ≦ (m−k) / 2. Note that m can be increased by increasing s in step b1), but e is also increased.

  In the initialization phase, t inverted bits as early as possible are specified. Here, t is assumed to be the initial setting phase assumed inversion bit number. For this reason, in the test process, when a considerably large inversion bit number is generated as compared with the initial setting phase assumed inversion bit number t, the refresh stop time is set to be small and the inversion bit number becomes the initial setting phase assumption inversion bit number t. Set the refresh stop time in the initial setting phase so that it is close. In the SDRAM used in the experiment, the estimation of the initial setting phase refresh stop time corresponding to the initial setting phase assumed inversion bit number t = 20 is about 22, 6, 2, 1 seconds at −5, 25, 45, and 65 ° C, respectively. It was. In this experiment, when n = 100 inversion of test processing, n = 100, n1 = 25, n2 = 500, J1 = 6 (seconds), J2 = 2 (seconds) are substituted into [Equation 1]. Thus, the initial setting phase refresh stop time J is set to J = 400/475 * 6 + 75/475 * 2 = 5.4 (seconds). As data for holding the temperature information in the initial setting phase, it is sufficient to hold the actual inversion bit number n in the test processing in the initial setting phase. It is appropriate to evaluate the actual initial setting phase refresh stop time as 27, 11, 7 and 6 seconds, including the refresh stop time of 5 seconds of the test process in the initial setting phase.

  The key generation phase assumed inversion bit number s depends on the temperature during execution of the initialization phase, and the key generation phase assumption inversion bit number increases as the temperature difference between the temperature during execution of the initialization phase and the temperature during execution of the key generation phase increases. s gets bigger. As the key generation phase assumed inversion bit number s increases, the error data chaff data is often selected in step b2) of the Fuzzy Vault, so the key generation phase assumption inversion bit number s is the same as the set B1 and the key. The product set with the inverted bit set of the generation phase is equal to or larger than the first predetermined size, and the product set (set treated as noise) of the complement of the set B1 and the inverted bit set of the key generation phase is the second It is desired to set the size to be equal to or smaller than a predetermined size so that a correct key can be generated. The key generation phase assumed inversion bit number s is implicitly included in the key generation phase refresh stop time in the table (shown in parentheses in the table of FIG. 6), and thus the above set B1 And the set of inverted bits in the key generation phase is greater than or equal to the first predetermined size, and the product set (set treated as noise) of the complement of the set B1 and the set of inverted bits in the key generation phase is the first 2 It is desirable to set the key generation phase refresh stop time so as to be equal to or smaller than the predetermined size. Further, the initial setting phase refresh stop time affects the set B1, and therefore, the product set of the set B1 and the set of inverted bits of the key generation phase is equal to or larger than the first predetermined size, and the set B1 It is desirable to set the initial setting phase refresh stop time so that the product set of the complement set and the inverted bit set of the key generation phase (set treated as noise) is equal to or smaller than the second predetermined size.

  Thus, after determining the key generation phase assumed inversion bit number s, the key generation phase refresh stop time for achieving the key generation phase assumption inversion bit number s at each temperature is obtained, thereby obtaining the key generation phase in this embodiment. The refresh processing stop time is determined.

  FIG. 6 is an example of a refresh stop time table when the refresh stop time determined in this way is set. The number in parentheses in the key generation phase refresh stop time column is the assumed inversion bit number (key generation phase assumed inversion bit number) s. For example, suppose that the number of inverted bits n of the test process in the initial setting phase is n≈25, and the number of inverted bits n ′ of the test process in the key generation phase is n′≈500. In this example, the initial setting phase refresh stop time is set to 6 seconds corresponding to the test processing inversion bit number n ′ ≈25 in the initial setting phase, and the key generation phase refresh stop time is set to 25 ° C. in the key generation phase. Set to 2.2 seconds (25 inversion bits) shown in the 45 ° C line. In general, this is reflected in the refresh stop time as follows.

  With respect to the inversion bit number n obtained in the test processing of steps 420 to 440 in the initial setting phase, the adjacent test processing inversion bit numbers n1 and n2 in the refresh stop time table are selected so that n1 <n <n2. Also, for the inverted bit number n ′ obtained in the test process of steps 520 to 540 in the key generation phase, the adjacent test process inverted bit numbers n1 ′ and n2 ′ in the refresh stop time table are set to n1 ′ <n ′ <n2 Choose to be '. T (n1 ′, n1) represents the refresh processing stop time of the key generation phase corresponding to the inverted bit numbers n1, n1 ′ of the above two test processes (the test process in the initial setting phase and the test process in the key generation phase) And T (n1 ', n2), T (n2', n1), and T (n2 ', n2) are also expressed in the same manner. At this time, when two-dimensional linear interpolation is used, the refresh stop time J is obtained by [Equation 2].

[Formula 2]
J1 '= (n2-n) / (n2-n1) * T (n1', n1)
+ (n-n1) / (n2-n1) * T (n1 ', n2),
J2 '= (n2-n) / (n2-n1) * T (n2', n1)
+ (n-n1) / (n2-n1) * T (n2 ', n2),
J = (n2'- n ') / (n2'- n1') * J1 '
+ (n'- n1 ') / (n2'- n1') * J2 '
For example, in FIG. 6, when the initial setting phase n = 100 (n1 = 25, n2 = 500) and the key generation phase n ′ = 300 (n1 ′ = 25, n2 ′ = 500), J1 ′ = 6.3, J2 ′ = 2.16, so J = 3.9 (seconds). The refresh processing stop time in the entire key generation phase is evaluated as 8.9 seconds, including 5 seconds of the test processing.

  The device-specific information generation apparatus can be realized by hardware, software, or a combination thereof. The device specific information generation method performed by the device specific information generation apparatus can also be realized by hardware, software, or a combination thereof. Here, “realized by software” means realized by a computer reading and executing a program.

  The program can be stored and provided to a computer using various types of non-transitory computer readable media. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media (for example, flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (for example, magneto-optical disks), CD-ROMs (Read Only Memory), CD- R, CD-R / W, and semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (random access memory)). The program may also be supplied to the computer by various types of transitory computer readable media. Examples of transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

  A part or all of the above-described embodiment can be described as in the following supplementary notes, but is not limited thereto.

(Appendix 1)
A device-specific information generation device that generates device-specific information,
Assuming inversion that is the number of inversion bits necessary to generate the unique information based on the number of inversion bits that is the number of inversion bits generated by the test processing after performing the test processing for stopping the refresh for the test time Refresh stop time determining means for determining a refresh stop time corresponding to the number of bits;
Unique information generating means for generating the unique information based on information about the inverted bit obtained by the refresh stop applying the determined refresh stop time;
A device-specific information generating apparatus comprising:

(Appendix 2)
A device-specific information generation device according to attachment 1, wherein
A table holding a correspondence relationship between the test processing inversion bit number and the refresh stop time;
The device for generating device-specific information, wherein the refresh stop time determining means determines the refresh stop time based on the test process inversion bit number and the table.

(Appendix 3)
A device-specific information generation apparatus according to appendix 2,
The test process inversion bit number related to the correspondence in the table corresponds to the temperature at the time of the test process execution and the test time,
The device-specific information generating apparatus according to claim 1, wherein the refresh stop time associated with the correspondence relationship in the table corresponds to the temperature at the time of execution of the test process and the assumed number of inversion bits.

(Appendix 4)
A device-specific information generation device according to attachment 1, wherein
The unique information generating means generates the unique information based on information on the inverted bit obtained by stopping the refresh in the initial setting phase and information on the inverted bit obtained by stopping the refresh in the key generating phase,
The refresh stop time determining means includes
In the initial setting phase, an initial setting phase test process for stopping refreshing for a test time is performed, and the unique information is based on the inversion bit number that is the number of inversion bits generated by the initial setting phase test process. Initial setting phase refresh stop time determining means for determining the refresh stop time corresponding to the initial setting phase assumed inversion bit number that is the number of inversion bits necessary for generating
In the key generation phase, a key generation phase test process for stopping refreshing for a test time is performed, a key setting phase test process which is the number of inverted bits generated by the key generation phase test process, and the initial setting phase test Key generation phase refresh stop time determination means for determining the refresh stop time corresponding to the key generation phase assumed inversion bit number which is the inversion bit number necessary for generating the unique information based on the processing inversion bit number When,
A device-specific information generating apparatus comprising:

(Appendix 5)
A device-specific information generation apparatus according to appendix 4,
A first table holding a correspondence relationship between the number of inversion bits of the initial setting phase test process and the refresh stop time;
A second table holding a correspondence relationship between the combination of the initial setting phase test process inversion bit number and the key setting phase test process inversion bit number, and the refresh stop time;
Further comprising
The initial setting phase refresh stop time determining means determines a refresh stop time corresponding to the initial setting phase assumed inversion bit number based on the initial setting phase test process inversion bit number and the first table. And
The key generation phase refresh stop time determining unit is configured to determine the key generation phase assumed inversion bit number based on the initial setting phase test process inversion bit number, the key generation phase test process inversion bit number, and the second table. A device-specific information generating apparatus, wherein a refresh stop time corresponding to the device is determined.

(Appendix 6)
A device-specific information generation device according to appendix 5,
The initial setting phase test process inversion bit number related to the correspondence relationship in the first table corresponds to the temperature at the time of the test process execution in the initial setting phase and the test time,
The refresh stop time related to the correspondence relationship in the first table corresponds to the temperature at the time of the test process execution in the initial setting phase and the number of assumed inversion bits of the initial setting phase,
The key setting phase test process inversion bit number related to the correspondence in the second table corresponds to the temperature and the test time when the test process is executed in the key setting phase,
The refresh stop time associated with the correspondence in the second table includes the temperature at the time of the test process execution in the initial setting phase, the temperature at the time of the test process execution in the key generation phase, and the key generation phase assumption inversion bit. A device-specific information generating apparatus, which corresponds to a number.

(Appendix 7)
The device-specific information generation device according to any one of appendices 4 to 6,
The unique information generating means includes
Means for generating redundant data of an error correction code for the specific information based on information about the inverted bit obtained by stopping the refresh in the initial setting phase;
Means for generating the unique information based on the information about the inverted bit obtained by stopping the refresh in the key generation phase and the redundant data;
A device-specific information generating apparatus comprising:

(Appendix 8)
A device-specific information generation device according to appendix 7,
The device specific information generation apparatus further comprising means for changing the redundancy of the error correction code in accordance with the number of inverted bits of the initial setting phase test process.

(Appendix 9)
The device-specific information generation device according to any one of appendices 4 to 8,
When the number of inversion bits generated by the key generation phase test process is equal to or less than a predetermined number, the initial setting phase refresh stop time is shortened, and further includes means for starting over from the initial setting phase. Device specific information generator.

(Appendix 10)
A device-specific information generation apparatus according to any one of appendices 1 to 9,
Device-specific information generation, further comprising means for correcting a refresh stop time corresponding to the assumed inversion bit number based on the inversion bit number obtained by the refresh stop applying the determined refresh stop time apparatus.

(Appendix 11)
A device specific information generation method for generating device specific information,
Assuming inversion that is the number of inversion bits necessary to generate the unique information based on the number of inversion bits that is the number of inversion bits generated by the test processing after performing the test processing for stopping the refresh for the test time A refresh stop time determination step for determining a refresh stop time corresponding to the number of bits;
A unique information generating step for generating the unique information based on information on the inversion bit obtained by the refresh stop applying the determined refresh stop time;
A device-specific information generation method characterized by comprising:

(Appendix 12)
A device-specific information generation method according to appendix 11,
A table holding a correspondence relationship between the test processing inversion bit number and the refresh stop time;
The device for generating device-specific information, wherein the refresh stop time determining step determines the refresh stop time based on the test process inversion bit number and the table.

(Appendix 13)
A device-specific information generation method according to attachment 12, comprising:
The test process inversion bit number related to the correspondence in the table corresponds to the temperature at the time of the test process execution and the test time,
The device-specific information generation method, wherein the refresh stop time associated with the correspondence relationship in the table corresponds to the temperature at the time of execution of the test process and the assumed number of inversion bits.

(Appendix 14)
A device-specific information generation method according to appendix 11,
In the unique information generating step, the unique information is generated based on information on the inverted bit obtained by stopping the refresh in the initial setting phase and information on the inverted bit obtained by stopping the refresh in the key generating phase,
The refresh stop time determining step includes:
In the initial setting phase, an initial setting phase test process for stopping refreshing for a test time is performed, and the unique information is based on the inversion bit number that is the number of inversion bits generated by the initial setting phase test process. An initial setting phase refresh stop time determination step for determining a refresh stop time corresponding to the initial setting phase assumed inversion bit number that is the number of inversion bits necessary for generating
In the key generation phase, a key generation phase test process for stopping refreshing for a test time is performed, a key setting phase test process which is the number of inverted bits generated by the key generation phase test process, and the initial setting phase test A key generation phase refresh stop time determination step for determining a refresh stop time corresponding to the key generation phase assumed inversion bit number which is the number of inversion bits necessary for generating the unique information based on the processing inversion bit number When,
A device-specific information generation method characterized by comprising:

(Appendix 15)
A device-specific information generation method according to attachment 14, wherein
A first table holding a correspondence relationship between the number of inversion bits of the initial setting phase test process and the refresh stop time;
A second table holding a correspondence relationship between the combination of the initial setting phase test process inversion bit number and the key setting phase test process inversion bit number, and the refresh stop time;
Use
In the initial setting phase refresh stop time determining step, a refresh stop time corresponding to the initial set phase assumed inversion bit number is determined based on the initial setting phase test process inversion bit number and the first table. And
In the key generation phase refresh stop time determination step, the key generation phase assumed inversion bit number based on the initial setting phase test process inversion bit number, the key generation phase test process inversion bit number, and the second table A device-specific information generation method, wherein a refresh stop time corresponding to the device is determined.

(Appendix 16)
A device-specific information generation method according to attachment 15, wherein
The initial setting phase test process inversion bit number related to the correspondence relationship in the first table corresponds to the temperature at the time of the test process execution in the initial setting phase and the test time,
The refresh stop time related to the correspondence relationship in the first table corresponds to the temperature at the time of the test process execution in the initial setting phase and the number of assumed inversion bits of the initial setting phase,
The key setting phase test process inversion bit number related to the correspondence in the second table corresponds to the temperature and the test time when the test process is executed in the key setting phase,
The refresh stop time associated with the correspondence in the second table includes the temperature at the time of the test process execution in the initial setting phase, the temperature at the time of the test process execution in the key generation phase, and the key generation phase assumption inversion bit. A device-specific information generation method characterized in that it corresponds to a number.

(Appendix 17)
A device-specific information generation method according to any one of appendices 14 to 16,
The specific information generating step includes
Generating redundant data of an error correction code for the specific information based on information on inversion bits obtained by stopping refresh in the initialization phase;
Generating the unique information based on the information related to the inverted bits obtained by stopping the refresh in the key generation phase and the redundant data;
A device-specific information generation method characterized by comprising:

(Appendix 18)
A device-specific information generation method according to appendix 17,
The device specific information generation method further comprising a step of changing the redundancy of the error correction code according to the number of inverted bits of the initial setting phase test process.

(Appendix 19)
A device-specific information generation method according to any one of appendices 14 to 18,
The method further comprises the step of shortening the initial setting phase refresh stop time and starting over from the initial setting phase when the number of inverted bits generated by the key generation phase test process is equal to or less than a predetermined number. Device specific information generation method.

(Appendix 20)
The device-specific information generation method according to any one of appendices 11 to 19,
The device specific information generation further comprising a step of correcting a refresh stop time corresponding to the assumed inversion bit number based on the inversion bit number obtained by the refresh stop applying the determined refresh stop time. Method.

(Appendix 21)
A device-specific information generation program for causing a computer to function as a device-specific information generation device that generates device-specific information,
Computer
Assuming inversion that is the number of inversion bits necessary to generate the unique information based on the number of inversion bits that is the number of inversion bits generated by the test processing after performing the test processing for stopping the refresh for the test time Refresh stop time determining means for determining a refresh stop time corresponding to the number of bits;
Unique information generating means for generating the unique information based on information about the inverted bit obtained by the refresh stop applying the determined refresh stop time;
Device specific information generation program to function as a device.

(Appendix 22)
A device-specific information generation program according to appendix 21,
Further, the computer is caused to function as a table holding a correspondence relationship between the test processing inversion bit number and the refresh stop time,
The device for generating device-specific information, wherein the refresh stop time determining means determines the refresh stop time based on the test process inversion bit number and the table.

(Appendix 23)
A device-specific information generation program according to attachment 22,
The test process inversion bit number related to the correspondence in the table corresponds to the temperature at the time of the test process execution and the test time,
The device-specific information generation program characterized in that the refresh stop time associated with the correspondence relationship in the table corresponds to the temperature at the time of execution of the test process and the assumed number of inversion bits.

(Appendix 24)
A device-specific information generation program according to appendix 21,
The unique information generating means generates the unique information based on information on the inverted bit obtained by stopping the refresh in the initial setting phase and information on the inverted bit obtained by stopping the refresh in the key generating phase,
The refresh stop time determining means includes
In the initial setting phase, an initial setting phase test process for stopping refreshing for a test time is performed, and the unique information is based on the inversion bit number that is the number of inversion bits generated by the initial setting phase test process. Initial setting phase refresh stop time determining means for determining the refresh stop time corresponding to the initial setting phase assumed inversion bit number that is the number of inversion bits necessary for generating
In the key generation phase, a key generation phase test process for stopping refreshing for a test time is performed, a key setting phase test process which is the number of inverted bits generated by the key generation phase test process, and the initial setting phase test Key generation phase refresh stop time determination means for determining the refresh stop time corresponding to the key generation phase assumed inversion bit number which is the inversion bit number necessary for generating the unique information based on the processing inversion bit number When,
A device-specific information generation program comprising:

(Appendix 25)
A device specific information generation program according to attachment 24,
Computer,
A first table holding a correspondence relationship between the number of inversion bits of the initial setting phase test process and the refresh stop time;
A second table holding a correspondence relationship between the combination of the initial setting phase test process inversion bit number and the key setting phase test process inversion bit number, and the refresh stop time;
Function as
The initial setting phase refresh stop time determining means determines a refresh stop time corresponding to the initial setting phase assumed inversion bit number based on the initial setting phase test process inversion bit number and the first table. And
The key generation phase refresh stop time determining unit is configured to determine the key generation phase assumed inversion bit number based on the initial setting phase test process inversion bit number, the key generation phase test process inversion bit number, and the second table. A device-specific information generation program that determines a refresh stop time corresponding to the device.

(Appendix 26)
A device-specific information generation program according to attachment 25, wherein
The initial setting phase test process inversion bit number related to the correspondence relationship in the first table corresponds to the temperature at the time of the test process execution in the initial setting phase and the test time,
The refresh stop time related to the correspondence relationship in the first table corresponds to the temperature at the time of the test process execution in the initial setting phase and the number of assumed inversion bits of the initial setting phase,
The key setting phase test process inversion bit number related to the correspondence in the second table corresponds to the temperature and the test time when the test process is executed in the key setting phase,
The refresh stop time associated with the correspondence in the second table includes the temperature at the time of the test process execution in the initial setting phase, the temperature at the time of the test process execution in the key generation phase, and the key generation phase assumption inversion bit. A device-specific information generation program characterized by corresponding to a number.

(Appendix 27)
A device-specific information generation program according to any one of appendices 24 to 26,
The unique information generating means includes
Means for generating redundant data of an error correction code for the specific information based on information about the inverted bit obtained by stopping the refresh in the initial setting phase;
Means for generating the unique information based on the information about the inverted bit obtained by stopping the refresh in the key generation phase and the redundant data;
A device-specific information generation program comprising:

(Appendix 28)
A device specific information generation program according to attachment 27,
A device-specific information generating program for causing a computer to further function as means for changing the redundancy of the error correction code according to the number of inverted bits of the initial setting phase test process.

(Appendix 29)
A device-specific information generation program according to any one of appendices 24 to 28,
Further, when the number of inverted bits generated by the key generation phase test process is equal to or less than a predetermined number, the computer is caused to function as means for reducing the initial setting phase refresh stop time and starting over from the initial setting phase. For generating device-specific information.

(Appendix 30)
A device-specific information generation program according to any one of appendices 21 to 29,
A device-specific function for causing a computer to further function as means for correcting the refresh stop time corresponding to the assumed inversion bit number based on the inversion bit number obtained by the refresh stop applying the determined refresh stop time. Information generation program.

  The present invention can be used for device authentication.

100 Authentication Unit 110 Specific Information Generation Unit 120, 200 Device Physical Information Generation Unit 130, 250 Physical Information Mapping Unit 140 Interface 150 Terminal Device 160 Server 210 DRAM Device 220 R / W Controller 230 Refresh Control Unit 240 Refresh Stop Time Table 420-490 Step 520-590 in the initial setting phase Step in the key generation phase

Claims (9)

A device-specific information generation device that generates device-specific information,
Assuming inversion that is the number of inversion bits necessary to generate the unique information based on the number of inversion bits that is the number of inversion bits generated by the test processing after performing the test processing for stopping the refresh for the test time Refresh stop time determining means for determining a refresh stop time corresponding to the number of bits;
Unique information generating means for generating the unique information based on information about the inverted bit obtained by the refresh stop applying the determined refresh stop time;
A device-specific information generating apparatus comprising: The device specific information generating apparatus according to claim 1,
A table holding a correspondence relationship between the test processing inversion bit number and the refresh stop time;
The device for generating device-specific information, wherein the refresh stop time determining means determines the refresh stop time based on the test process inversion bit number and the table. The device specific information generating apparatus according to claim 2,
The test process inversion bit number related to the correspondence in the table corresponds to the temperature at the time of the test process execution and the test time,
The device-specific information generating apparatus according to claim 1, wherein the refresh stop time associated with the correspondence relationship in the table corresponds to the temperature at the time of execution of the test process and the assumed number of inversion bits. The device specific information generating apparatus according to claim 1,
The unique information generating means generates the unique information based on information on the inverted bit obtained by stopping the refresh in the initial setting phase and information on the inverted bit obtained by stopping the refresh in the key generating phase,
The refresh stop time determining means includes
In the initial setting phase, an initial setting phase test process for stopping refreshing for a test time is performed, and the unique information is based on the inversion bit number that is the number of inversion bits generated by the initial setting phase test process. Initial setting phase refresh stop time determining means for determining the refresh stop time corresponding to the initial setting phase assumed inversion bit number that is the number of inversion bits necessary for generating
In the key generation phase, a key generation phase test process for stopping refreshing for a test time is performed, a key setting phase test process which is the number of inverted bits generated by the key generation phase test process, and the initial setting phase test Key generation phase refresh stop time determination means for determining the refresh stop time corresponding to the key generation phase assumed inversion bit number which is the inversion bit number necessary for generating the unique information based on the processing inversion bit number When,
A device-specific information generating apparatus comprising: The device specific information generating apparatus according to claim 4,
A first table holding a correspondence relationship between the number of inversion bits of the initial setting phase test process and the refresh stop time;
A second table holding a correspondence relationship between the combination of the initial setting phase test process inversion bit number and the key setting phase test process inversion bit number, and the refresh stop time;
Further comprising
The initial setting phase refresh stop time determining means determines a refresh stop time corresponding to the initial setting phase assumed inversion bit number based on the initial setting phase test process inversion bit number and the first table. And
The key generation phase refresh stop time determining unit is configured to determine the key generation phase assumed inversion bit number based on the initial setting phase test process inversion bit number, the key generation phase test process inversion bit number, and the second table. A device-specific information generating apparatus, wherein a refresh stop time corresponding to the device is determined. The device specific information generating apparatus according to claim 5,
The initial setting phase test process inversion bit number related to the correspondence relationship in the first table corresponds to the temperature at the time of the test process execution in the initial setting phase and the test time,
The refresh stop time related to the correspondence relationship in the first table corresponds to the temperature at the time of the test process execution in the initial setting phase and the number of assumed inversion bits of the initial setting phase,
The key setting phase test process inversion bit number related to the correspondence in the second table corresponds to the temperature and the test time when the test process is executed in the key setting phase,
The refresh stop time associated with the correspondence in the second table includes the temperature at the time of the test process execution in the initial setting phase, the temperature at the time of the test process execution in the key generation phase, and the key generation phase assumption inversion bit. A device-specific information generating apparatus, which corresponds to a number. The device specific information generation apparatus according to any one of claims 4 to 6,
The unique information generating means includes
Means for generating redundant data of an error correction code for the specific information based on information about the inverted bit obtained by stopping the refresh in the initial setting phase;
Means for generating the unique information based on the information about the inverted bit obtained by stopping the refresh in the key generation phase and the redundant data;
A device-specific information generating apparatus comprising: A device specific information generation method for generating device specific information,
Assuming inversion that is the number of inversion bits necessary to generate the unique information based on the number of inversion bits that is the number of inversion bits generated by the test processing after performing the test processing for stopping the refresh for the test time A refresh stop time determination step for determining a refresh stop time corresponding to the number of bits;
A unique information generating step for generating the unique information based on information on the inversion bit obtained by the refresh stop applying the determined refresh stop time;
A device-specific information generation method characterized by comprising: A device-specific information generation program for causing a computer to function as a device-specific information generation device that generates device-specific information,
Computer
Assuming inversion that is the number of inversion bits necessary to generate the unique information based on the number of inversion bits that is the number of inversion bits generated by the test processing after performing the test processing for stopping the refresh for the test time Refresh stop time determining means for determining a refresh stop time corresponding to the number of bits;
Unique information generating means for generating the unique information based on information about the inverted bit obtained by the refresh stop applying the determined refresh stop time;
Device specific information generation program to function as a device.

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