JP2001339385A - Encryption unit and encryption method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an encryption unit and an encryption method that can realize encryption with high reliability by devising the position of a seed in concealed data that it cannot be externally retrieved. SOLUTION: A seed and concealed data encrypted by using the seed for a key are read from an EEPROM 12, encryption is applied to the concealed data by using the seed for a key and the decoded data are stored with the seed. A random number is generated by using the stored seed, and encryption is conducted on the basis of the generated random number. The stored seed is updated on the basis of the generated random number, encryption is applied to the concealed data by using the updated seed for a key and an LSI 13 stores the encrypted data to the EEPROM 12 with the updated seed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an encryption processing apparatus and an encryption processing method for performing encryption processing using device-specific data uniquely set for each device.

[0002]

2. Description of the Related Art As is well known, an encryption processing apparatus as described above is conventionally configured as shown in FIG.
That is, the device main body 11 of this encryption processing device includes E
EPROM (Electrically Erasable and Programmable
Read Only Memory (12) and LSI (Large Scale Int)
egrated circuit) 13.

On the other hand, a factory for manufacturing the encryption processing apparatus is provided with a memory 14 for storing device-specific data uniquely set for each device. This device individual data is
It is composed of secret data including a seed that serves as a seed for random number generation and public data.

In this manufacturing plant, the device individual data stored in the memory 14 is
It is stored in the EEPROM 12. In this case, the encryption circuit 15 adds a certain key f (k) to the secret data including the seed.
, And the public data is passed as it is.

[0005] For this reason, the encryption processing apparatus stores the secret data encrypted with the seed by the function key f (k) in the EEPROM 12 of the device main body 11 and the secret data stored in the memory 14 of the manufacturing factory. The public data as it is is stored and shipped.

[0006] In such a state, when the encryption processing device is requested to perform encryption processing, the LSI 13 executes the EEPRO.
The secret data and the public data encrypted together with the seed are read from M12, and RA
It is stored in an M (Random Access Memory) unit 13b.

In this case, the decryption unit 13a stores the key f (k) only in the secret data encrypted with the seed.
, And the public data is passed as it is. For this reason, the device individual data in the state stored in the memory 14 is stored in the RAM unit 13b.

Then, based on the decoded seed stored in the RAM 13b, the random number generator 13
c generates a random number, and performs an encryption process using the random number, the secret data and the public data stored in the RAM unit 13b.

When the encryption process is completed in this manner, the random number generated by the random number generation unit 13c is used as a seed for the next random number generation as a RAM unit 13c.
b. That is, the seed of the RAM unit 13b is
The seed read from the EEPROM 12 and decrypted is changed to a new value.

Thereafter, the device individual data stored in the RAM unit 13b is transferred to the EEPROM 1 via the encryption unit 13e.
2 and the encryption process ends. In this case, the encryption unit 13e performs encryption processing on the secret data including the seed using the key f (k), and passes the public data as it is.

[0011]

However, in the above-described conventional encryption processing apparatus, a key f (k) for decrypting secret data including a seed read from the EEPROM 12 and a secret key decrypted together with the seed are used. The key f (k) for encrypting data is the same, and only the seed is updated with a random number.

For this reason, from the EEPROM 12 to the LSI 1
3 and EEPR from LSI 13
When the secret data transferred to the OM 12 is read and compared, only the seed has a different value, so that the position of the seed in the secret data can be easily searched.

As described above, when the position of the seed in the confidential data is detected, "0" is input to the position of the seed each time, so that the encryption process is performed with "0". As a result, there is a problem that the state is substantially the same as the state where the encryption processing is not performed.

Therefore, the present invention has been made in view of the above circumstances, and it is possible to prevent the position of a seed in confidential data from being searched from the outside, thereby realizing highly reliable encryption. It is an object of the present invention to provide an encryption apparatus and an encryption method which are very good.

[0015]

According to the present invention, there is provided an encryption processing apparatus comprising: a memory in which a seed, secret data encrypted by using the seed as a key are stored, and a seed and a secret from the memory. A decryption unit that reads the data and decrypts the secret data using the seed as a key,
A storage unit that stores the secret data decrypted by the decryption unit and the seed read from the memory, a random number generation unit that generates a random number based on the seed stored in the storage unit, and a random number generation unit. An encryption processing unit that performs an encryption process based on the generated random number; an updating unit that updates a seed stored in the storage unit based on a random number generated by the random number generation unit; Encrypt the secret data stored in the storage unit using the seed as a key,
An integrated circuit having an encryption unit that stores the updated seed in a memory together with the updated seed.

Further, the encryption processing method according to the present invention provides:
A first step of reading the seed and the confidential data from a memory in which the seed and the confidential data subjected to the encryption processing using the seed as a key are stored, and performing decryption processing on the confidential data using the seed as a key; A second step of storing the secret data decrypted in the first step and the seed read from the memory, and a third step of generating a random number based on the seed stored in the second step. A fourth step of performing an encryption process based on the random number generated in the third step, and a fourth step of updating the seed stored in the second step based on the random number generated in the third step. 5 steps,
A sixth step of encrypting the secret data stored in the second step using the seed updated in the fifth step as a key and storing the encrypted data in the memory together with the updated seed is performed. Things.

According to the above configuration and method, the seed as a key for decrypting the secret data read from the memory is different from the seed as a key for encrypting the decrypted secret data. Even if the data transferred from the memory to the integrated circuit and the data transferred from the integrated circuit to the memory are read and compared with each other, the position of the seed cannot be searched, and highly reliable encryption is performed. Can be.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. In FIG. 1, the same parts as those in FIG. 2 will be denoted by the same reference numerals. In the manufacturing factory of the encryption processing device, the device individual data stored in the memory 14 Is stored in the EEPROM 12 using the seed stored in the memory 14 as a key, the encryption circuit 15 performs encryption processing only on the secret data excluding the seed, and stores the seed and the public data as they are.

For this reason, the encryption processing device stores the secret data encrypted by the seed in the EEPROM 12 of the device main body 11 and the unencrypted seed in the state stored in the memory 14 of the manufacturing factory. And the public data are stored and shipped.

In such a state, when the encryption processing device is requested to perform the encryption process, the LSI 13 executes the EEPRO
From M12, the encrypted confidential data, the seed and the public data are read out, and RA
It is stored in an M (Random Access Memory) unit 13b.

In this case, the decrypting section 13a performs decryption processing on the encrypted confidential data using the seed stored in the EEPROM 12 as a key, and passes the seed and the public data as they are. Therefore, the RAM unit 13
In b, the device individual data in the state stored in the memory 14 is stored.

The random number generator 13c generates a random number based on the seed stored in the RAM 13b, and the encryption processor 13d stores the random number based on the random number, for example, in the RAM 13b. An encryption process limited by the confidential data after the decryption process is executed.

When all the encryption processes are completed in this way, the random number generated by the random number generation unit 13c is used as a seed for the next random number generation by the RAM unit 13c.
b. That is, the seed of the RAM unit 13b is
The seed read from the EEPROM 12 is changed to a new value.

Thereafter, the device individual data stored in the RAM unit 13b is transferred to the EEPROM 1 via the encryption unit 13e.
2 and the encryption process ends. In this case, the encryption unit 13e uses the new seed stored in the RAM unit 13b as a key to perform encryption processing only on the secret data excluding the seed, and passes the seed and the public data as they are.

According to the above embodiment, EEPRO
Since the seed as a key for decrypting the confidential data read from the M12 and the seed as a key for encrypting the decrypted confidential data are different, the confidential data transferred from the EEPROM 12 to the LSI 13 and the Even if the secret data transferred to the secret data is read and compared, the position of the seed in the secret data cannot be searched, and highly reliable encryption can be performed.

It should be noted that the present invention is not limited to the above-described embodiment, and can be variously modified and implemented without departing from the scope of the present invention.

[0027]

As described in detail above, according to the present invention,
To provide an extremely good encryption processing apparatus and encryption processing method capable of realizing highly reliable encryption by preventing the position of a seed in confidential data from being externally searched. Can be.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an encryption processing device and an encryption processing method according to the present invention;

FIG. 2 is a block diagram for explaining a conventional encryption processing device.

[Explanation of symbols]

 11: device main body, 12: EEPROM, 13: LSI, 14: memory, 15: encryption circuit.

Claims (2)

[Claims] 1. A memory in which a seed, secret data encrypted by using the seed as a key are stored, and a seed and secret data are read from the memory, and the secret data is stored in the secret data using the seed as a key. A decryption unit for performing a decryption process, a storage unit for storing the secret data decrypted by the decryption unit and a seed read from the memory, and a random number generated based on the seed stored in the storage unit A random number generation unit, an encryption processing unit that performs an encryption process based on the random number generated by the random number generation unit, and a seed stored in the storage unit based on the random number generated by the random number generation unit. Updating means for updating, and encrypting the secret data stored in the storage unit using the seed updated by the updating means as a key, and writing the encrypted data in the memory together with the updated seed. Encryption processing apparatus characterized by comprising comprises an integrated circuit having an encryption unit for. 2. A seed and secret data are read from a memory in which a seed and secret data encrypted by using the seed as a key are stored, and the secret data is decrypted using the seed as a key. A first step of applying; a second step of storing the secret data decrypted in the first step and a seed read from the memory; and a random number based on the seed stored in the second step. A fourth step of performing encryption processing based on the random number generated in the third step, and a seed stored in the second step in the third step. A fifth step of updating based on the generated random numbers; and performing encryption processing on the secret data stored in the second step using the seed updated in the fifth step as a key;
And a sixth step of storing the updated seed in the memory together with the updated seed.