JP2003032248A - Cryptographic method, decoding method, and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To verify whether or not the decoding has been carried out correctly, with small processing power in a short time. SOLUTION: When cryptographic process is started, a previously set decoding certification code is added to the original data 30 and ciphered. A cryptographic header 41 is added to the cryptographic data 42 and stored as a memory data 34 in a memory card. The cryptographic header 41 is the information used for indicating the used cryptographic algorithm. When the data is decoded, whether or not the decoding is correct can be determined, by certifying only the decoding certification code.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an encryption method and a decryption method applicable to a mobile device, and
Regarding electronic devices.

[0002]

2. Description of the Related Art PDC (Personal D) which is known as an analog cellular system or a digital cellular system.
mobile phone systems such as igital Cellular telecommunication system, and simple mobile phone systems (PHS: Pe
In the rsonal Handyphone System), the mobile phone carried by the user can download the ringing melody for notifying the user of the incoming call when there is an incoming call and the image data of the background image displayed on the display. It is becoming possible. In addition, models that can download Java applications such as games have also appeared.

[0003]

A large amount of copyrighted data is contained in various data downloaded to a mobile phone, and a memory dial (telephone directory) requiring privacy protection for the mobile phone. There is data such as. When reading these data from the mobile phone to the outside, it is necessary to encrypt them for copyright protection or privacy protection. When encrypting,
The data is encrypted using any one of a plurality of encryption algorithms prepared for the mobile phone. The encrypted data is stored in, for example, a memory card mounted on the mobile phone. In this way, the data saved in the memory card can be taken into only the device itself, and the encrypted data taken into the mobile phone again can be decrypted using a predetermined decryption algorithm. Will be done.

However, since a plurality of encryption algorithms are prepared, a plurality of decryption algorithms corresponding to them are prepared, and since it is not known which decryption algorithm should be used for decryption, the decrypted data is correct. It was necessary to confirm whether it was decrypted. However, since it has to be confirmed whether all the data has been properly decoded, it is necessary to give a lot of processing power to the confirmation process and spend a lot of time. There was a problem that it had to be.

Therefore, the present invention provides an encryption method and a decryption method, and an electronic device, which can confirm whether or not they are correctly decrypted with a small processing power and a short time. Has an aim.

[0006]

In order to achieve the above object, the encryption method of the present invention uses the original data to be encrypted,
An addition step of adding a predetermined decryption confirmation code for confirming that the decryption has been performed correctly, and the original data to which the decryption confirmation code has been added is subjected to a predetermined encryption algorithm by the addition step. And an encryption header adding step of adding an encryption header containing information necessary for decryption to the encrypted data encrypted by the encryption step. The encrypted processing data subjected to the encryption processing is obtained from the step of adding the encrypted header. Further, in the encryption method of the present invention, the information of the encryption header may be information that can specify the encryption algorithm.

Next, the decryption method of the present invention that can achieve the above object is an encryption method that removes an encryption header from encrypted data and obtains information necessary for decryption from the encryption header. Decrypting the encrypted data from which the encrypted header has been removed from the encrypted data by the encrypted header removal step and a predetermined decryption algorithm based on the information necessary for decryption obtained in the encrypted header removal step And a removing step for confirming whether the decoding confirmation code of the decoded data decoded by the decoding step is correctly decoded and for removing the decoding confirmation code. Therefore, the decoded original data is obtained from the removing step.

Further, in the above decoding method of the present invention,
The information of the encryption header may be information that can specify the decryption algorithm. further,
In the above decoding method of the present invention, if the decoding confirmation code is not correctly decoded in the removing step, the decoded data may be discarded.

Next, in the electronic device of the present invention which can achieve the above object, a predetermined decryption confirmation code for confirming that the original data to be encrypted is properly decrypted is provided. Addition means for adding, encryption means for encrypting the original data to which the decryption confirmation code is added by the addition means by a predetermined encryption algorithm, and encrypted data encrypted by the encryption means , An encryption processing means comprising an encryption header adding means for adding an encryption header containing information necessary for decryption, and an encryption processing to which the encryption processing obtained from the encryption processing means is applied. The data can be stored in the storage means. Further, in the electronic device of the present invention, the information of the encryption header in the encryption processing means may be information that can specify the encryption algorithm.

Further, another electronic device of the present invention which can achieve the above object removes the encryption header from the encrypted data read from the storage means and subjected to the encryption process, and The encryption processing is performed by an encryption header removing unit that obtains information required when decrypting from the encryption header, and a predetermined decryption algorithm based on the information required when decrypting that is obtained by the encryption header removing unit. Decryption means for decrypting the encrypted data from which the encryption header has been removed from the data, and whether or not the decryption confirmation code of the decrypted data decrypted by the decryption means is correctly decrypted, Decryption processing means including removal means for removing the decryption confirmation code is provided, and the encryption processing data stored in the storage means is decrypted by the decryption processing means. And more decoded, so as to obtain the original data before being processed encrypted.

Furthermore, in the other electronic device of the present invention, the information of the encryption header in the decryption processing means may be information that can specify the decryption algorithm. Furthermore, in the other electronic device of the present invention, the decryption data may be discarded if the decryption confirmation code is not correctly decrypted by the removal unit in the decryption processing unit.

According to the present invention as described above, the copyrighted data and the data requiring privacy protection are encrypted to maintain their security.
At this time, since a predetermined decryption confirmation code was added to the original data for encryption, only the decryption confirmation code was confirmed when decrypting to determine whether the decryption was successful or not. It becomes possible to detect such a thing with a little processing power and a little time. If the information required for decryption, for example, the information that can identify the encryption algorithm, is used as the encryption header, the decryption algorithm can be identified based on the information in the encryption header when performing the decryption. The conversion process can be executed with a small amount of processing power and a small amount of time.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a configuration example of an embodiment of an electronic apparatus according to the present invention in which the encryption method and the decryption method of the present invention are executed. FIG. 1 shows an embodiment in which the electronic device according to the present invention is applied to a mobile device. The mobile device 1 shown in FIG. 1 is a mobile phone in a mobile communication system. The mobile device 1 includes an antenna 2, which is connected to an RF circuit 11.
The RF circuit 11 includes a transmission / reception circuit and a modulation / demodulation circuit. The modulation / demodulation circuit in the RF circuit 11 includes a voice codec circuit 12 and a channel codec circuit 1.
Connected to 5. The voice codec circuit 12 voice-compresses and decodes the reception signal demodulated by the modulation / demodulation circuit into a voice signal, and also voice-compresses and codes the input voice signal into a transmission signal. That is, the voice codec circuit 12 performs high-efficiency compression encoding of a voice signal for transmission and decodes it into a voice signal for reception, and is, for example, a CELP (Code Excited LPC) type codec. The audio signal output from the audio codec circuit 12 is applied to the speaker 13, and the audio signal input from the microphone 14 is supplied to the audio codec circuit 12.

The RF circuit 11 is also connected to a channel codec circuit 15 for performing data codec processing. The channel codec circuit 15 performs data compression / decompression processing and scramble / descramble processing. For example, when the received signal is data, the data supplied from the RF circuit 11 to the channel codec circuit 15 is processed. The descramble process and the decompression process are performed, and the reproduced data is stored in the RAM 19. Further, the data input to the channel codec circuit 15 is subjected to compression processing and scramble processing, is output via the RF circuit 11, and is transmitted from the antenna 2. The memory card interface (I / O) 16 is an interface of the memory card 3 which is detachably attached to the mobile device 1. The memory card I / O 16 is provided with a slot, and the memory card 3 is attached to this slot.

Central Processing Uni
(t: CPU) 17 is a system control unit that controls the operation of each unit of the mobile device 1 by executing a telephone function program, and indicates the elapsed time during operation or generates a timer interrupt at a specific time interval. Equipped with a timer to Also,
The CPU 17 executes the encryption program and the decryption program, thereby executing the encryption process and the decryption process described later. The ROM 18 stores various telephone function programs for transmission processing and reception processing executed by the CPU 17, an encryption program and a decryption program, and a ROM (Read Only Memory) storing programs such as a plurality of encryption algorithms and a plurality of decryption algorithms. Is. Further, a decryption confirmation code described later is stored. R
AM 19 is a storage area for user setting data, a storage area for downloaded incoming melody and image data, C
RAM (Random
Access Memory). Each functional block exchanges data and commands via the bus 20. Also,
Although not shown, the mobile device 1 is equipped with a rechargeable secondary battery.

Next, an encryption method and a decryption method according to the embodiment of the present invention executed in the mobile device 1 described above will be described with reference to FIGS. 2 and 3. FIG. 2 is a diagram showing a configuration of processing means for executing the encryption method and the decryption method according to the embodiment of the present invention. Although shown as a block, the CPU 17 actually causes the encryption program and the decryption program to be executed. It is realized by executing a program. FIG. 3 shows a data structure in each step in the encryption method and the decryption method according to the present invention. The original data 30 to be encrypted is RA
It is stored in M19. The original data 30 is, for example, data of a ringing melody having a copyright downloaded in the mobile device 1, image data, or data such as a memory dial (telephone book) requiring privacy protection. When these data are stored in the memory card 3 attached to the mobile device 1, they are encrypted in order to prohibit their use by other devices.

When this encryption process is started, the RAM 1
The original data 30 to be encrypted is read from 9, and the decryption confirmation code adding means 31 adds the decryption confirmation code 40 as shown in S2 in FIG. The decryption confirmation code 40 is a predetermined code that differs for each mobile device 1, and is stored in the ROM 18 in advance. Then, by confirming whether or not the decryption confirmation code 40 decrypted at the time of the decryption processing and the decryption confirmation code 40 stored in the ROM 18 match, the decryption confirmation code 40 is correctly decrypted. It is possible to determine whether or not there is. Note that depending on the type of data to be encrypted, data that may be commonly used by all devices may be considered, and in this case, the decryption confirmation code 40 common to all devices may be used.

The data obtained by adding the decryption confirmation code 40 to the original data 30 is encrypted by the encryption means 32 having a plurality of encryption algorithms using the encryption key unique to the device itself. At this time, an optimum encryption algorithm is selected from among a plurality of encryption algorithms according to the degree of security of data and the like, and encryption is performed using the selected encryption algorithm and the own encryption key. The encrypted header 42 is added to the encrypted encrypted data 42 by the encryption header adding means 33 as shown in S3 of FIG. Information that constitutes the encryption header 41 can include information that indicates the encryption algorithm used. Further, other information can be put in the encrypted header 41, and the encrypted header 41 is expandable.

The encrypted data 42 added with the encrypted header 41 that has been encrypted in this way is transferred to the memory card 3 mounted on the mobile device 1 through the memory card I / O 16 and the memory card Will be stored in 3. That is, in the memory card 3, S4 in FIG.
The encrypted data 42 with the encrypted header 41 added thereto is stored as the storage data 34 as shown in FIG.

Next, a decryption process of decrypting the encrypted storage data 34 stored in the memory card 3 and loading it into the mobile device 1 will be described. When the decryption processing is started, the storage data 34 is read from the memory card 3 and the memory card I / I is read as shown in S11 of FIG.
It is taken into the mobile device 1 side via O16. The stored header 34 is decrypted by the encrypted header decryption / removal means 35, and the encrypted header 41 is separated and removed as shown in S12 of FIG. That is, only the encrypted data 42 is output from the encrypted header decoding / removing means 35.
The encrypted data 42 is decrypted by the decryption means 36 having a plurality of decryption algorithms using the encryption key unique to the device itself. At this time, the encryption algorithm can be specified from the information of the decrypted encryption header 41, and the corresponding decryption algorithm can be selected. Therefore, it is possible to eliminate the need to change the decoding algorithm many times to perform decoding.

For the data decrypted by the decryption means 36, the decryption confirmation code 40 is decrypted by the decryption confirmation code decryption / removal means 37, and S13 in FIG.
The decryption confirmation code 40 is separated and removed as shown in FIG. In decoding the decryption confirmation code 40, a match with the decryption confirmation code 40 stored in the ROM 18 is detected, and if it is confirmed that the decryption is correct, the decryption processing is completed, and the decryption confirmation code 40 From the removing means 37,
Only the decrypted original data 30 will be output.
The decrypted original data 30 is stored in the RAM 19. In decoding the decryption confirmation code 40, the decryption confirmation code 40 stored in the ROM 18
If no match is detected and it is determined that the data has not been correctly decoded, it is determined that the data is not data that can be decoded by the mobile device 1, and the data is discarded.

In the above description, the encryption method and the decryption method according to the present invention have been described as being applied to a mobile device such as a mobile phone, but the present invention is not limited to this, and a memory card should be attached. The present invention can be applied to electronic devices that can be used. Further, as the encryption key unique to the device itself used in the encryption process and the decryption process, either a common key system encryption key or a public key system encryption key can be used. Furthermore, although the saved data is supposed to be saved in the memory card, it is not limited to the storage means that can be detachably attached like a memory card,
It may be a storage means built in the mobile device or the electronic device. The stored data stored in the built-in storage means can be loaded into another mobile device or an external electronic device through an interface provided in the mobile device or the electronic device.

[0023]

As described above, the present invention encrypts copyrighted data or data requiring privacy protection to maintain its security. At this time, since a predetermined decryption confirmation code was added to the original data for encryption, only the decryption confirmation code was confirmed when decrypting to determine whether the decryption was successful or not. It becomes possible to detect such a thing with a little processing power and a little time. If the information required for decryption, for example, the information that can identify the encryption algorithm, is used as the encryption header, the decryption algorithm can be identified based on the information in the encryption header when performing the decryption. The conversion process can be executed with a small amount of processing power and a small amount of time. In particular, since the CPU power is low in the mobile device, the encryption method and the decryption method are suitable.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of an embodiment of an electronic apparatus according to the present invention in which an encryption method and a decryption method of the present invention are executed.

FIG. 2 is a diagram showing a configuration of processing means for executing the encryption method and the decryption method according to the exemplary embodiment of the present invention.

FIG. 3 is a diagram showing a data structure in each step in the encryption method and the decryption method according to the exemplary embodiment of the present invention.

[Explanation of symbols]

1 mobile unit, 2 antennas, 3 memory card, 11
RF circuit, 12 audio codec circuit, 13 speaker, 14 microphone, 15 channel codec circuit, 1
6 memory card I / O, 17 CPU, 18 RO
M, 19 RAM, 20 bus, 30 original data, 31
Decryption confirmation code adding means, 32 Encryption means, 33
Encryption header adding means, 34 stored data, 35 encryption header decoding / removing means, 36 decryption means, 37
Decryption confirmation code decoding / removal means, 40 decryption confirmation code, 41 encrypted header, 42 encrypted data

Continued front page    (72) Inventor Masato Fukaya             34 Shinanomachi Shinjuku-ku, Tokyo JR Shinanomachi Bi             Within Le JF East Japan Co., Ltd. (72) Inventor Akio Kikuchi             34 Shinanomachi Shinjuku-ku, Tokyo JR Shinanomachi Bi             Within Le JF East Japan Co., Ltd. F term (reference) 5J104 AA32 AA37 NA02 NA35 PA02

Claims (10)

[Claims] 1. An addition step of adding a predetermined decryption confirmation code for confirming that the decryption is correctly performed to the original data to be encrypted, and the decryption confirmation code by the addition step. An encryption step of encrypting the original data to which is added by a predetermined encryption algorithm, and the encrypted data encrypted by the encryption step,
An encryption header adding step of adding an encryption header including information necessary for decryption, and the encrypted processing data obtained by performing the encryption processing is obtained from the encryption header adding step. Encryption method. 2. The encryption method according to claim 1, wherein the information of the encryption header is information that can specify the encryption algorithm. 3. An encryption header removing step of removing an encryption header from encrypted processing data and obtaining information necessary for decryption from the encryption header, and a decryption obtained in the encryption header removing step. A decryption step of decrypting the encrypted data from which the encrypted header is removed from the encrypted data by a predetermined decryption algorithm based on the information necessary for decryption, and the decrypted data decrypted by the decrypting step. The decryption confirmation code includes a removal step for confirming whether the decryption confirmation code is correctly decoded and removing the decryption confirmation code, and the decrypted original data is obtained from the removal step. A decoding method characterized by the above. 4. The decryption method according to claim 3, wherein the information of the encryption header is information that can specify the decryption algorithm. 5. The removing step, wherein the decrypted data is discarded if the decryption confirmation code is not properly decrypted.
The described decryption method. 6. An addition unit for adding a predetermined decryption confirmation code for confirming that the decryption is correctly performed to the original data to be encrypted, and the addition unit.
An encryption unit that encrypts the original data to which the decryption confirmation code is added by a predetermined encryption algorithm, and the encrypted data encrypted by the encryption unit includes information necessary for decryption. An encryption processing means including an encryption header adding means for adding an encryption header is provided, and the encryption processing data that has been subjected to the encryption processing obtained from the encryption processing means can be stored in the storage means. An electronic device characterized by being present. 7. The electronic device according to claim 6, wherein the information of the encryption header in the encryption processing means is information that can specify the encryption algorithm. 8. The encryption header removal from the encryption processing data read out from the storage means and subjected to the encryption processing to obtain the information necessary for decryption from the encryption header. And a decryption for decrypting the encrypted data from which the encrypted header has been removed from the encrypted data, by means of a predetermined decryption algorithm based on the information necessary for decryption obtained by the encrypted header removing means. Decoding means for confirming whether the decoding confirmation code of the decoded data decoded by the decoding means is correctly decoded, and removing means for removing the decoding confirmation code. And decrypting the encrypted processing data stored in the storage means by the decryption processing means to obtain the original data before the encryption processing. Electronic devices, characterized in that. 9. The electronic device according to claim 8, wherein the information of the encryption header in the decryption processing means is information that can specify the decryption algorithm. 10. The electronic device according to claim 8, wherein the removal means in the decryption processing means discards the decrypted data when the decryption confirmation code is not properly decrypted. machine.