JP6724732B2 - Electronic control unit - Google Patents

Description

The present disclosure relates to a technique for managing rewriting of a rewritable nonvolatile memory included in an electronic control device.

Some electronic control devices store a program and data in a rewritable nonvolatile memory such as a flash memory. The data stored in the non-volatile memory may be rewritten by updating the version of the program or updating the data. Hereinafter, the program and the data are also simply referred to as data.

Rewriting of data in the non-volatile memory is performed, for example, by a rewriting tool connected to the electronic control unit. When rewriting the data in the non-volatile memory, it is known that the storage area of the non-volatile memory is divided into a plurality of blocks and only the block containing the data to be rewritten is rewritten.

Here, when the data in the non-volatile memory is rewritten, there is a possibility that the malicious rewriting may be performed by a malicious third party instead of the correct rewriting. In order to verify such unauthorized rewriting, there is known a technique of verifying whether or not the data stored in the non-volatile memory is valid at a predetermined timing (for example, refer to Patent Document 1).

JP, 2015-55898, A

When verifying the data in the non-volatile memory, for example, the digest of the block data is calculated for each block of the plurality of blocks in the non-volatile memory, and whether it matches the digest calculated from the digital signature stored in advance for each block. It is conceivable to verify the data of each block depending on whether or not.

However, in this verification method, since the digest is calculated by the number of blocks, there is a problem that the processing time required for verification increases as the number of blocks increases.
One aspect of the present disclosure provides a technique for reducing the processing time required to verify the validity of data in all areas stored in a nonvolatile memory having a plurality of blocks in which data can be rewritten for each block. ..

One aspect of the present disclosure is a nonvolatile memory (70), a rewritable nonvolatile storage unit (70, 100), a first calculation unit (S414, S480), and a second calculation unit (S416, S482) and a verification unit (S418, S484).

The non-volatile memory has a plurality of blocks in which data can be rewritten for each block. The rewritable non-volatile storage unit stores all-area digital signatures (96, 102) used for verifying the correctness of data in all areas of a plurality of blocks.

The first calculation unit calculates a first whole area digest from the data of the whole area. The second calculation unit calculates the second whole area digest from the whole area electronic signature stored in the storage unit using the verification key (64). The verification unit determines whether or not the first full-area digest calculated by the first calculation unit and the second full-area digest calculated by the second calculation unit match at a predetermined timing. Based on, the validity of the data in all areas is verified.

According to this structure, one first whole area digest is calculated from the data of all areas without calculating the digest for each block. Then, based on the determination result of whether or not the one second whole-area digest calculated from the whole-area digital signature matches the first whole-area digest, all the blocks of the non-volatile memory are Verify the legitimacy of the area data.

When verifying the correctness of the data in all areas of the non-volatile memory, the first whole area digest and the second whole area digest may be calculated one by one, so that the processing time required for the verification can be shortened.

Note that the reference numerals in parentheses described in this column and in the claims indicate the correspondence with the specific means described in the embodiments described below as one aspect, and do not indicate the technical scope of the present disclosure. It is not limited.

The block diagram which shows the electronic control unit of 1st Embodiment. The flowchart which shows a verification process. The flowchart which shows a rewriting process. Explanatory drawing which shows the process of a rewriting process. The block diagram which shows the electronic controller of 2nd Embodiment. The flowchart which shows a verification process. The flowchart which shows a rewriting process.

Hereinafter, an embodiment to which the present disclosure is applied will be described based on the drawings.
[1. First Embodiment]
[1-1. Constitution]
The electronic control unit 2 shown in FIG. 1 is equipped with a microcomputer including a communication unit 10, a CPU 20, a RAM 30, a ROM 40, and a flash memory 70. Hereinafter, the electronic control unit is also referred to as an ECU.

The communication unit 10 communicates with an external rewriting tool 200 connected to the communication unit 10. Communication between the ECU 2 and the rewriting tool 200 may be wired or wireless. The CPU 20 executes a program stored in the ROM 40 or the flash memory 70. The RAM 30 is used as a temporary data storage area when the CPU 20 executes a program.

The ROM 40 includes a secure area 50 and a boot area 60. The flash memory 70 includes an OS area 80 and an application program area 90. Hereinafter, the application program is also simply referred to as an application.

The secure area 50 stores a secure program 52, a digest generation key 54, and a digest expected value 56. The secure program 52 is a program that verifies the legitimacy of the boot loader 62. The digest generation key 54 is a secret key for calculating the digest from the data of the boot loader 62. The expected digest value 56 is a value of a digest expected to be calculated from valid boot loader 62 data.

In the boot area 60, a boot loader 62 and a digital signature verification key 64 which is a public key are stored. The boot loader 62 verifies the validity of the OS 82 and activates the OS 82. The electronic signature verification key 64 is used to calculate the digest from the electronic signature and to encrypt the digest.

The OS area 80 stores an OS 82 and an OS electronic signature 84 used when the boot loader 62 verifies the validity of the OS 82.
The application area 90 includes a plurality of blocks that store a plurality of applications. Although FIG. 1 illustrates four blocks corresponding to four applications, the number of blocks in the application area 90 is not limited to four and may be any number.

In each block of the application area 90, an application 92, an application electronic signature 94, an entire area electronic signature 96, and a counter 98 are stored.
The application electronic signature 94 is an electronic signature for verifying the validity of the data of each application 92. The application electronic signature 94 is rewritten by the electronic signature transmitted from the rewriting tool 200 together with the rewriting data when the application 92 of the corresponding block is rewritten.

The entire area electronic signature 96 is an electronic signature for verifying the validity of the data in the entire area of the application area 90. When the block to be rewritten is rewritten, the entire area electronic signature 96 is calculated from the rewriting data, the electronic signature of the rewriting data, and the data excluding the entire area electronic signature 96 and the counter 98 from the blocks other than the rewriting target. It is rewritten by the electronic signature calculated from the digest.

The counter 98 is discriminating information for discriminating which of the all-area electronic signatures 96 stored in each block is the latest. For example, the value of the counter 98 of the block in which the latest full area electronic signature 96 is stored is set to the maximum value larger than that of other blocks.

The rewriting tool 200 includes a communication unit 210 that communicates with the ECU 2. Furthermore, the rewriting tool 200 stores an electronic signature generation key 220 which is a secret key used when decrypting the encrypted digest transmitted from the ECU 2 and calculating an electronic signature from the decrypted digest. The rewriting tool 200 is connected to the ECU 2 when rewriting a block to be rewritten in the application area 90.

[1-2. processing]
(1) Verification Processing The verification processing of the data in the ROM 40 and the flash memory 70 will be described based on the flowchart of FIG. The flowchart of FIG. 2 is executed when the power of the ECU 2 is turned on and the ECU 2 is activated.

In S400, the CPU 20 executes the secure program 52 to calculate the digest of the boot loader 62 using the digest generation key 54. In S402, the CPU 20 determines whether or not the digest calculated in S400 and the expected digest value 56 of the boot loader 62 stored in advance in the secure area 50 match.

If the determination in S402 is No, and the digest calculated in S400 does not match the expected digest value 56, the CPU 20 in S404 executes the abnormality determination process and then ends the verification process in FIG. As a result, the ECU 2 ends the process without executing the application 92. As the abnormality determination processing in S404, the cause of the abnormality is stored in the error code area of the flash memory 70 as an error code or the like.

If the determination in S402 is Yes and the digest calculated in S400 matches the expected digest value 56, the secure program 52 activates the boot loader 62.
Then, in S406, the CPU 20 executes the boot loader 62 to calculate the digest of the data in the OS area 80 using a hash function or the like.

In S408, the CPU 20 uses the electronic signature verification key 64, which is a public key, to calculate the expected digest value of the data in the OS area 80 from the OS electronic signature 84 stored in the OS area 80. In S410, the CPU 20 determines whether the digest calculated in S406 matches the expected digest value calculated in S408.

If the determination in S410 is No, and the digest calculated in S406 does not match the expected digest value calculated in S408, the CPU 20 executes the abnormality determination process in S404 described above, and then ends the verification process.

If the determination in S410 is Yes and the digest calculated in S406 and the expected digest value calculated in S408 match, the boot loader 62 activates the OS 82. Then, in S412 to S420, the CPU 20 executes the OS 82 to verify the data in the application area 90.

In S412, the CPU 20 refers to the counter 98 of each block, determines that the all-area electronic signature 96 of the block in which the maximum-value counter 98 is stored is the latest, and extracts the latest all-area electronic signature 96.

For example, when the data of the block to be rewritten is rewritten, the counter 98 of the block to be rewritten is updated by, for example, incrementing the value of the counter 98, which has been the maximum until then, by +1. Thus, by referring to the value of the counter 98 stored in each block, it is possible to find the block of the application area 90 in which the latest all area electronic signature 96 is stored.

When the CPU 20 extracts the latest all-area electronic signature 96 in S412, the CPU 20 calculates the digest of the data in all areas of the application area 90 from a hash function or the like in S414.
It should be noted that, in each block, the application electronic signature 94 is included in the data of all the areas to be calculated when the digest is calculated in order to verify the data of all the areas of the application area 90. The counter 98 is excluded.

This is because the latest all-area electronic signature 96 generated in the rewriting process described later cannot be generated from the data including the latest all-area electronic signature 96. The counter 98 is discrimination information for discriminating the latest electronic signature 96 of all areas, and is data set together with the electronic signature 96 of all areas. Therefore, in this embodiment, data of all areas of the application area 90 is verified. It is excluded from the target data when calculating the digest.

In S416, the CPU 20 uses the electronic signature verification key 64 stored in the boot area 60 to calculate the expected digest value of the entire area data of the application area 90 from the latest electronic signature 96 of the entire area.

In S418, the CPU 20 determines whether or not the digest calculated in S414 matches the expected digest value calculated in S416.
When the determination in S418 is No and the digest calculated in S414 does not match the expected digest value calculated in S416, the CPU 20 executes the abnormality determination process in S404 described above, and then ends the verification process.

If the determination in S418 is Yes and the digest calculated in S414 matches the expected digest value calculated in S416, the CPU 20 ends the verification process in FIG. 2 after executing the normality determination process in S420. In the normality determination processing, the CPU 20 prepares an environment in which the application 92 in the application area 90 can be executed and shifts the processing to the corresponding application 92.

(2) Rewriting Process of Rewriting Tool 200 The rewriting process for the application area 90 of the flash memory 70 will be described based on the flowchart of FIG. The flowchart of FIG. 3 is executed by the ECU 2 and the rewriting tool 200 when the rewriting tool 200 is connected to the ECU 2. In FIG. 3, the flowchart represented by the reference numeral 300 is executed by the rewriting tool 200, and the flowchart represented by the reference numeral 310 is executed by the ECU 2.

When the rewriting tool 200 is connected to the ECU 2, the rewriting tool 200 transmits the rewriting data for the block of the application area 90 to be rewritten and the electronic signature of the rewriting data from the communication unit 210 to the ECU 2 in S430. Then, the rewriting tool 200 waits until the communication unit 210 receives the encrypted digest described below from the ECU 2.

In the application area 90, the encrypted digest received from the ECU 2 is the rewriting data of the block to be rewritten, the electronic signature of the rewriting data, and the entire area electronic signature 96 and the counter 98 from the blocks other than the rewriting target. It is calculated from the data.

When the rewriting tool 200 receives the encrypted digest calculated by the ECU 2 in S432, the rewriting tool 200 uses the electronic signature generation key 220, which is the secret key stored in the rewriting tool 200, in S434 to encrypt the received digest in S432. Decrypt the digest that was done.

In S436, the rewriting tool 200 uses the electronic signature generation key 220 to generate an electronic signature from the digest decrypted in S434. In S438, the rewriting tool 200 transmits the electronic signature generated in S436 to the ECU 2 and waits until the communication unit 210 receives the rewriting result from the ECU 2.

When the rewriting tool 200 receives the rewriting normal end as the rewriting result from the ECU 2, the rewriting tool 200 executes the rewriting normal end process of notifying the normal end from the display, the lamp, the speaker, etc. of the rewriting tool 200, and ends the rewriting process.

When the rewriting tool 200 receives the rewriting abnormal end as the rewriting result from the ECU 2, the rewriting tool 200 executes the rewriting abnormal end process of notifying the abnormal end from the display, the lamp, the speaker or the like of the rewriting tool 200 in S442, and ends the rewriting process.

(3) Rewriting Process of ECU 2 When the rewriting tool 200 is connected, the communication unit 10 of the CPU 20 receives the rewriting data for the block of the application area 90 to be rewritten and the electronic signature of the rewriting data from the rewriting tool 200 in S450. Until then, execution of the flowchart 310 is awaited.

When the communication unit 10 receives the rewriting data and the electronic signature of the rewriting data from the rewriting tool 200 in S450, the CPU 20 calculates a digest from the received rewriting data by a hash function or the like in S452. In S454, the CPU 20 uses the electronic signature verification key 64 stored in the boot area 60 to calculate the digest expected value of the rewrite data from the received electronic signature.

In S456, the CPU 20 determines whether or not the digest calculated in S452 and the expected digest value calculated in S454 match.
When the determination in S456 is No, and the digest calculated in S452 does not match the expected digest value calculated in S454, the CPU 20 in S458 transmits to the rewriting tool 200 that the rewriting data is invalid, and the rewriting process is performed. finish.

If the determination in S456 is Yes, and the digest calculated in S452 and the expected digest value calculated in S454 match, in S460, the CPU 20 causes the rewrite data, the electronic signature of the rewrite data, and all blocks from the block other than the rewrite target. A digest is calculated by a hash function or the like from the data excluding the area electronic signature 96 and the counter 98.

In S460, the CPU 20 further refers to the value of the counter 98 of each block, increments the value of the counter 98 having the maximum value, and stores it in the RAM 30.
In S462, the CPU 20 encrypts the digest calculated in S460 using the electronic signature verification key 64. In S464, the CPU 20 transmits the digest encrypted in S462 to the rewriting tool 200, and waits in S466 until the electronic signature generated by the rewriting tool 200 is received from the rewriting tool 200.

When the CPU 20 receives the electronic signature from the rewriting tool 200 in S466, in S468, the rewriting data received in S450, the electronic signature of the rewriting data received in S450, the counter value stored in the RAM 30 in S460, and the receiving in S466. The application 92, the application electronic signature 94, the counter 98, and the entire area electronic signature 96 are rewritten in the block to be rewritten with the electronic signature. By rewriting the counter 98 of the block to be rewritten with the counter value stored in the RAM 30, the value of the counter 98 becomes the latest information.

For example, as shown in FIG. 4, when data is first written in all blocks of the application area 90, the CPU 20 sets the entire area electronic signature received from the rewriting tool 200 and, for example, “1” as the initial value of the counter 98. , Write to any block. In FIG. 4, the full-area digital signature received from the rewriting tool 200 and the initial value of the counter 98 are written in the block of the application 1. The entire area electronic signatures 96 and the counters 98 of the other applications 2 to 4 are “NULL”.

After that, when the data of the application 3 and the application 2 are rewritten in order, the entire area electronic signature 96 and the counter 98 of the application 3 and the application 2 are rewritten in order.
When the determination in S470 is Yes and the rewriting of the block to be rewritten ends normally, the CPU 20 transmits the rewriting normal end to the rewriting tool 200 in S472, and ends the rewriting process.

If the determination in S470 is No, and rewriting of the block to be rewritten did not end normally, in S474, the CPU 20 sends a rewriting abnormal end to the rewriting tool 200, and ends the rewriting process.

[1-3. effect]
The following effects can be obtained in the first embodiment described above.
(1) When the ECU 2 is started, one digest is calculated from the data of all the areas of the application area 90, and the CPU 20 determines whether or not one digest expected value calculated from the latest all-area electronic signature 96 matches. The validity of the data in the area 90 is verified.

With this, without lowering the verification accuracy, rather than calculating the digest from the data of each block of the application area 90 and calculating the digest expected value from the electronic signature of each block to verify the validity of the data, The processing time required for verification can be shortened.

(2) In the rewriting process, the rewriting tool 200 uses the electronic signature generation key 220 stored in the rewriting tool 200 to generate an electronic signature corresponding to the entire-area electronic signature 96. It is not necessary to transmit the signature generation key 220 and generate the entire area electronic signature 96 on the ECU 2 side. As a result, it is possible to suppress the possibility of leakage of the electronic signature generation key 220 that is the private key.

(3) In the rewriting process, the rewriting tool 200 generates an electronic signature corresponding to the entire area electronic signature 96. Therefore, a tool other than the ECU 2 and the rewriting tool 200 generates an electronic signature corresponding to the entire area electronic signature 96 in advance. There is no need to keep it.

(4) During the rewriting process, the ECU 2 encrypts and transmits the digest of the data in the application area 90 to the rewriting tool 200. Therefore, what kind of data is being transmitted from the ECU 2 to the rewriting tool 200 is given to a third party. It can suppress being detected.

(5) Since the entire area electronic signature 96 and the counter 98 are stored in the same flash memory 70 as the application, in order to store the entire area electronic signature 96 and the counter 98, a memory different from the flash memory 70 is stored. There is no need to prepare.

In the first embodiment, the ECU 2 corresponds to an electronic control unit, the communication unit 10 corresponds to a communication unit, the flash memory 70 corresponds to a nonvolatile memory having a plurality of rewritable blocks, and the entire area The area of the flash memory 70 storing the electronic signature 96 corresponds to the storage unit, and the rewriting tool 200 corresponds to the rewriting tool.

Further, the electronic signature verification key 64 corresponds to the verification key, the electronic signature generation key 220 corresponds to the secret key, the entire area electronic signature 96 corresponds to the entire area electronic signature, and the counter 98 corresponds to the discrimination information.
Further, S414, S452, and S460 correspond to the processing of the first calculation unit, S416 and S454 correspond to the processing of the second calculation unit, S418 and S456 correspond to the processing of the verification unit, and S450, S458, S464, S466, S472, and S474 correspond to the processing of the communication unit, S462 corresponds to the processing of the encryption unit, and S468 corresponds to the processing of the data rewriting unit and the signature rewriting unit.

Further, the digest calculated in S414 corresponds to the first full-area digest, the expected digest value calculated in S416 corresponds to the second full-area digest, and the electronic data of the rewriting data received from the rewriting tool 200 in S450. The signature corresponds to the data electronic signature, the digest calculated in S452 corresponds to the first block digest, the digest expected value calculated in S454 corresponds to the second block digest, and the digest calculated in S460 is Corresponds to the third full-area digest.

[2. Second Embodiment]
[2-1. Differences from the first embodiment]
Next, the configuration of the nonvolatile memory according to the second embodiment will be described. The same components as those of the first embodiment are designated by the same reference numerals. The same reference numerals as in the first embodiment refer to the preceding description.

As shown in FIG. 5, in the ECU 4 of the second embodiment, one full area electronic signature 102 for all areas of the application area 90 is stored in a flash memory 100 different from the flash memory 70 including the application area 90. .. In addition, one whole area electronic signature 102 may be stored in an area different from the application area 90 of the same flash memory 70.

[2-2. processing]
(1) Verification Processing Data verification processing of the ROM 40 and the flash memory 70 will be described based on the flowchart of FIG. The flowchart of FIG. 6 is executed when the power of the ECU 4 is turned on and the ECU 4 is activated. S400 to S410 and S420 of FIG. 6 are substantially the same processes as S400 to S410 and S420 of FIG.

In S480, the CPU 20 calculates a digest of data in the entire area of the application area 90 from a hash function or the like. In S482, the CPU 20 uses the electronic signature verification key 64 stored in the boot area 60 to obtain the expected digest value of the data in all areas of the application area 90 from the entire area electronic signature 102 stored in the flash memory 100. calculate.

In S484, the CPU 20 determines whether or not the digest calculated in S480 matches the expected digest value calculated in S482.
(2) Rewriting Process The rewriting process for the application area 90 of the flash memory 70 will be described based on the flowchart of FIG. 7. The flowchart of FIG. 7 is executed by the ECU 2 and the rewriting tool 200 when the rewriting tool 200 is connected to the ECU 2.

S430 to S442, S450 to S458, S470 to S474 of FIG. 7 are substantially the same processes as S430 to S442, S450 to S458, and S470 to S474 of FIG.
In S490, the CPU 20 calculates a digest from the rewrite data, the electronic signature of the rewrite data, and the data excluding the full-area electronic signature 96 and the counter 98 from the blocks other than the rewrite target, using a hash function or the like.

In S492, the CPU 20 encrypts the digest calculated in S490 using the electronic signature verification key 64. In S494, the CPU 20 transmits the digest encrypted in S492 to the rewriting tool 200, and waits in S496 until the electronic signature generated by the rewriting tool 200 is received from the rewriting tool 200.

In S498, the CPU 20 rewrites the entire area electronic signature 102 stored in the flash memory 100 with the electronic signature received from the rewriting tool 200 in S496.
In S500, the CPU 20 rewrites the application 92 and the application electronic signature 94 of the block to be rewritten with the rewriting data received from the rewriting tool 200 in S450 and the electronic signature of the rewriting data.

[2-3. effect]
According to the second embodiment, the effect of replacing the latest full-area digital signature 96 with the full-area digital signature 102 in the effect (1) of the first embodiment and the effects (2) to (4) of the first embodiment. And can be obtained.

Furthermore, according to the second embodiment, only one whole-area digital signature 102 needs to be stored regardless of the number of blocks in the application area 90, so the amount of memory used for storing the whole-area electronic signature 102 is reduced. it can.

In the second embodiment, the full-area digital signature 102 corresponds to the full-area digital signature, and the area of the flash memory 100 storing the full-area digital signature 102 corresponds to the storage unit.
In the second embodiment, S480 and S490 correspond to the processing of the first calculation unit, S482 corresponds to the processing of the second calculation unit, S484 corresponds to the processing of the verification unit, and S492 encrypts. S494, S496 correspond to the processing of the communication unit, S498 corresponds to the processing of the signature rewriting unit, and S500 corresponds to the processing of the data rewriting unit.

[3. Other Embodiments]
(1) In the above-described embodiment, the ECUs 2 and 4 encrypt the digest calculated from the data in the application area 90 and send it to the rewriting tool 200. On the other hand, the digest calculated from the data in the application area 90 may be directly transmitted to the rewriting tool 200 without being encrypted.

(2) In the rewriting process, the ECUs 2 and 4 may receive the electronic signature generation key 220 together with the rewriting data from the rewriting tool 200 and generate the entire-area electronic signature of the data in the entire area of the application area 90.

In this case, the ECUs 2 and 4 do not need to encrypt the digest calculated from the rewrite data and the data of the block other than the rewrite target and send the digest to the rewrite tool 200, but only the rewrite result to the rewrite tool 200. As a result, the amount of communication between the ECUs 2 and 4 and the rewriting tool 200 is reduced, so that the rewriting time can be shortened.

(3) If the rewriting tool 200 stores and manages the data content of all areas of the application area 90 before rewriting based on the rewriting data transmitted to the ECUs 2 and 4 so far, this rewriting The rewriting tool 200 can generate a full-area digital signature using the digital signature generation key 220, which is a secret key, from the data in the entire area of the application area 90 when the block to be rewritten by the data is rewritten.

With this configuration, in the rewriting process, the rewriting tool 200 transmits the rewriting data, the electronic signature of the rewriting data, and the entire area electronic signature to the ECUs 2 and 4.
(4) In the above embodiment, the verification process is executed when the ECUs 2 and 4 are powered on and the ECUs 2 and 4 are activated at a predetermined timing. Other than this, for example, the verification process may be executed at a predetermined time interval as a predetermined timing.

(5) In the first embodiment, in the verification process, the CPU 20 refers to the counter 98 of each block, and sets the latest full-area digital signature 96 to the full-area electronic signature 96 of the block in which the maximum counter 98 is stored. Was extracted as.

On the other hand, the latest full area electronic signature 96 may be extracted by the following method. First, in the rewriting process, the CPU 20 stores the number of rewritings in the flash memory 70 or the like, and rewrites the counter 98 of the block to be rewritten with the number of rewriting processes. Next, in the verification process, the CPU 20 extracts, as the latest full-area digital signature 96, the full-area digital signature 96 of the block in which the counter 98 that matches the number of rewrites stored in the flash memory 70 or the like is stored.

(6) A plurality of functions of one constituent element in the above-described embodiment may be realized by a plurality of constituent elements, or one function of one constituent element may be realized by a plurality of constituent elements. Further, a plurality of functions of a plurality of constituent elements may be realized by one constituent element, or one function realized by a plurality of constituent elements may be realized by one constituent element. Moreover, you may omit a part of structure of the said embodiment. Further, at least a part of the configuration of the above-described embodiment may be added or replaced with respect to the configuration of the other above-described embodiment. Note that all aspects included in the technical idea specified only by the wording recited in the claims are embodiments of the present disclosure.

(7) In addition to the ECUs 2 and 4 described above, an electronic control system including the ECUs 2 and 4 as components, a data verification program and a data rewriting program for causing a computer to function as the ECUs 2 and 4, the data verification program and the data rewriting The present disclosure can be realized in various forms such as a recording medium recording a program, a data verification method, and a data rewriting method.

2, 4: ECU (electronic control unit), 10: communication unit, 20: CPU, 64: electronic signature verification key (verification key), 70: flash memory (rewritable non-volatile memory, storage unit), 96, 102 : All-area digital signature, 98: Counter (discrimination information), 100: Flash memory (storage unit), 200: Rewriting tool, 220: Digital signature generation key (secret key)

Claims (8)

It has a plurality of blocks rewritable data for each block, a storage unit for storing the entire area electronic signature (96) used to verify the validity of the data of all areas of the plurality of blocks for each of the blocks A non-volatile memory (70) in which the full-area digital signature stored in the storage unit of the block to be rewritten is rewritten when data in any one of the plurality of blocks is rewritten ,
A first calculation unit ( S414 ) for calculating a first whole-area digest from the data of the whole area;
Based on the discrimination information (98) for discriminating which one of the all-area electronic signatures stored for each block is the latest, a verification key (64) is used from the latest all-area electronic signature to obtain the first A second calculation unit ( S416 ) for calculating the full-area digest of 2;
At a predetermined timing, a determination result of whether or not the first full-area digest calculated by the first calculation unit and the second full-area digest calculated by the second calculation unit are coincident with each other. A verification unit ( S418 ) for verifying the correctness of the data in all the areas based on
An electronic control unit ( 2 ) comprising. The electronic control unit according to claim 1,
A communication unit ( 10, S450, S458, S464, S466, S472, S474 ) for communicating with an external rewriting tool (200),
Further, when the communication unit receives the rewrite data for the rewrite target block among the plurality of blocks from the rewrite tool, the first calculation unit (S460) and the data of the block other than the rewrite target and the communication unit Calculates a third full-area digest from the rewriting data received from the rewriting tool,
A signature rewriting unit that rewrites the full-area digital signature with an electronic signature generated from the third full-area digest calculated by the first calculation unit by the rewriting tool or the electronic control device using a secret key (220). ( S468 )
And a data rewriting unit ( S468 ) for rewriting the data of the block to be rewritten with the rewriting data.
Electronic control unit. The electronic control unit according to claim 1,
A communication unit (10) for communicating with an external rewriting tool (200),
The rewriting tool manages the contents of the data in the entire area before rewriting based on the rewriting data for the block to be rewritten that the rewriting tool has transmitted to the communication unit.
The communication unit uses an electronic signature generated by the rewriting tool using the secret key (220) based on the data in the entire area when the block to be rewritten is rewritten by the rewriting data this time, and Receiving the rewriting data from the rewriting tool,
A signature rewriting unit ( S468 ) for rewriting the full-area digital signature with the digital signature received by the communication unit;
A data rewriting unit ( S468 ) for rewriting the data of the block to be rewritten with the rewriting data received by the communication unit,
Electronic control unit. The electronic control unit according to claim 2 or 3,
Furthermore, the first calculation unit (S452) calculates a first block digest from the rewrite data,
Further, the second calculator (S454) calculates a second block digest using the verification key from the data electronic signature of the rewrite data received from the rewrite tool together with the rewrite data,
Further, the verification unit (S456) determines whether or not the first block digest calculated by the first calculation unit and the second block digest calculated by the second calculation unit match. Based on the determination result, verify the validity of the rewrite data,
When the verification unit determines that the first block digest and the second block digest match, the data rewriting unit rewrites the data of the block to be rewritten with the rewriting data and rewrites the signature. The unit rewrites the whole area electronic signature with the electronic signature calculated using the secret key,
Electronic control unit. The electronic control device according to claim 2 or claim 4 which cites claim 2,
The communication unit ( S464, S466 ) transmits the third full-area digest to the rewrite tool, and uses the secret key to calculate the electronic signature calculated by the rewrite tool from the third full-area digest. Received from the rewriting tool,
The signature rewriting unit rewrites the whole area electronic signature with the electronic signature received from the rewriting tool,
Electronic control unit. The electronic control device according to claim 5, wherein:
Further comprising an encryption unit ( S462 ) for encrypting the third full-area digest,
The communication unit transmits the third full-area digest encrypted by the encryption unit to the rewriting tool, and uses the secret key from the third full-area digest decrypted by the rewriting tool. Receive the electronic signature to be generated from the rewriting tool,
Electronic control unit. The electronic control device according to claim 2 or claim 4 which cites claim 2,
Further, the signature rewriting unit generates an electronic signature from the third whole area digest using the secret key, and rewrites the whole area electronic signature with the generated electronic signature.
Electronic control unit. The electronic control device according to any one of claims 2 to 7 , wherein:
The storage unit stores the discrimination information in addition to the all-area electronic signature,
The signature rewriting unit rewrites the determination information corresponding to the block to be rewritten to the latest information when rewriting the full-area digital signature of the storage unit corresponding to the block to be rewritten,
Electronic control unit.

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