JPH10271107A - Data encryption method and device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide both an encryption key and encrypted data with portability to prevent leakage to the outside, and to drastically improve the strength against decryption by a third party. A data encryption method and apparatus are provided. SOLUTION: A security section 22 set inside a computer card 21, a control section 23 for generating a required encryption key (Kcd11) using random numbers, a random number generation section 25, and a generated encryption key (Kcd11). ), An encryption method storage unit 26 that previously stores an encryption method (Af11) that functions in accordance with the generated encryption key (Kcd11), and a stored encryption method (Af11). The encryption / decryption unit 24 that performs encryption processing (Pc11) on the received plaintext data (Df11) to create encrypted data (Dc11), and encrypted data that stores the created encrypted data (Dc11). And a storage unit 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data encryption method and apparatus, and more particularly, to data transmitted on an open network connected to an information terminal apparatus or stored in the information terminal apparatus itself. In encrypting and protecting the data, for example, a data encryption method in which an external device used by connecting to the information terminal device such as a computer card (so-called PC card) is given the function thereof, It relates to a data encryption device used directly for implementation.

[0002]

2. Description of the Related Art In recent years, data has been eavesdropped or altered by a third party in an open network such as a telephone line, ISDN (Integrated Services Digital Communication Network), LAN (Local Information Network), wireless communication network, or optical communication network. Various techniques for dealing with threats such as spoofing or spoofing are being studied. As the most typical example, plaintext data is encrypted by a predetermined encryption algorithm, and the encrypted data created by this encryption is used for transmission on an actual network or storage in an information terminal device. Known data encryption techniques are known.

When a system (encryption system) to which this type of data encryption technology is applied is configured, conventionally, as shown in FIG. 9, the information terminal device 1 converts plaintext data Df1 to encrypted data Dc1. Performs the encryption process Pc1 of
In addition, an application system 2 (encryption algorithm) for performing the decryption process Pd1 from the encrypted data Dc1 to the plaintext data (reconstruction) Dd1 is installed, and the encryption process Pc1 and the decryption process Pd1 are actually performed in the application system 2. At this time, an encryption key Kcd1, which is secret information unique to the user or the system, is used.

Here, the encryption processing P of the application system 2
The encrypted data Dc1 encrypted from the plaintext data Df1 via c1 is stored in the encrypted data storage unit 3 in the information terminal device 1.
The information terminal device 1 reads the encrypted data from the encrypted data storage unit 3 as necessary.
Is transmitted over an open network (not shown) connected to the Internet. On the other hand, the encryption key Kcd1, which is secret information, is, for example,
The data is further encrypted using a secret key (not shown) in the public key cryptosystem and stored in the encryption key storage unit 4 in the same information terminal device 1.

When the encryption key Kcd1 is stored, in addition to using the above-described encryption key storage unit 4 in the information terminal device 1, in order to further enhance the confidentiality, for example,
This may be performed using an external storage device 5 that is always portable, such as a computer card having a hard disk function (in the figure, the external storage device 5 is stored in an encryption key storage unit 6 in the external storage device 5). The encryption key Kcd2 is shown).

Incidentally, the form (encryption method) of the actual encryption processing Pc1 in the above-mentioned application system 2 is usually shown in FIG.
As shown in FIG. 0, in performing encryption Pcc1 on the plaintext data Df1 to obtain the encrypted data Dc1, an encryption method Af1 using one type of fixed encryption algorithm (hereinafter, also simply referred to as “fixed method Af1”). And one kind of encryption key Kcd1 or Kcd2 corresponding to this (the decryption process Pd1 not shown is a reverse procedure of the procedure).

In the case of the above-described encryption method, since the encryption Pcc1 is actually performed only once,
The confidentiality of the encrypted data Dc1 cannot be said to be sufficient, and some measures for increasing this are desired. For this reason,
As shown in FIG. 11, the above process, that is, the process of encrypting Pcc1 using the encryption key Kcd1 or Kcd2 for obtaining the encrypted data Dc1 from the plaintext data Df1 and the fixed system Af1 is performed n times (n is After repeating (an integer of 2 or more), an encryption method for extracting the encrypted data Dc2 to be actually used is often used (a decryption process Pd1 not shown is a reverse procedure of the above procedure).

[0008]

As described above, in the conventional encryption system and encryption method, the encrypted data D
Although appropriate measures have been taken to ensure the confidentiality of c1 and the encryption key Kcd1 or Kcd2, the following problems still remain.

First, as described above, the encryption key Kcd1 or Kcd2 used in the encryption system shown in FIG. 9 is encrypted with a secret key or the like in order to secure confidentiality. 1 or the encryption key storage unit 6 in the external storage device 5, but the encryption processing Pc1 is actually performed by the encryption system.
Is always decrypted once and expanded on a main memory (not shown) in the information terminal device 1.

For this reason, for example, when a person familiar with the configuration of this type of cryptographic system attempts to use the cryptographic system illegally, the cryptographic system developed on the main memory by the unauthorized user is used. The existence or meaning of the key Kcd1 or Kcd2 is easily recognized, and there is a danger that the contents thereof will be easily leaked to the outside. In particular, when the encryption key Kcd1 is stored on the side of the encryption key storage unit 4 in the information terminal device 1, there is a risk that the encryption key Kcd1 may be stolen or erased by an unauthorized user. In this regard, the encryption key Kcd is always stored on the side of the encryption key storage unit 6 in the external storage device 5.
2 can be saved, and when the cryptographic system is not used, the external storage device 5 is detached from the information terminal device 1 and is always carried, so that the above danger can be avoided. Should be actively utilized in technical improvement.

Second, in connection with the above problem, the encrypted data Dc1 created in the encryption system shown in FIG.
Is always stored in the encrypted data storage unit 3 in the information terminal device 1, so that the information is not portable at all.
As in the case described above, there is a risk that the encrypted data Dc1 may be stolen or erased by an unauthorized user.

Third, in the encryption systems shown in FIGS. 10 and 11, only one encryption system Af1 using a fixed encryption algorithm and one encryption key Kcd1 or a corresponding encryption key Kcd1 are used. Since only Kcd2 is used, there is a risk that the created encrypted data Dc1 or Dc2 may be decrypted relatively easily by information collection by a third party.

In particular, in the encryption system shown in FIG. 11, a normal process is repeated n times in order to improve confidentiality. Therefore, a simple calculation is required until the final encrypted data Dc2 is obtained. This requires n times as long as a normal process, and for example, when the encrypted data Dc2 is used for network transmission, it is extremely disadvantageous in terms of data transmission speed.

Here, the main objects to be solved by the present invention are as follows. That is, a first object of the present invention is to provide a data encryption method and apparatus in which both an encryption key and encrypted data are provided with portability to prevent leakage thereof to the outside. .

A second object of the present invention is to provide a data encryption method and a data encryption apparatus which can remarkably improve the strength of a third party against decryption.

Other objects of the present invention will become apparent from the description of the specification, the drawings, and particularly from the claims.

[0017]

In order to solve the above-mentioned problems, the present invention reciprocally transmits and receives data to and from an application system mounted on an information terminal device such as a highly portable computer card. An encryption function is assigned to an external device capable of performing the encryption function, and a required encryption key and encrypted data are generated and stored in a security area set inside the external device. Have.

More specifically, in solving the problem, the present invention achieves the above object by adopting each of the novel characteristic construction methods and means described below. .

That is, the first feature of the method of the present invention is that an external device capable of mutually transmitting and receiving data to and from an application system mounted on an information terminal device is used, and the external device is internally provided. In the set security area, a required encryption key is generated using a random number, and plaintext data received from an application system in the information terminal device using an encryption method that functions in accordance with the generated encryption key. The data encryption method is performed by applying an encryption process to generate encrypted data, storing the generated encryption key in the security area, and storing the generated encryption data in an area outside the security area. .

A second feature of the method of the present invention is that, prior to the generation of the encryption key in the first feature of the method of the present invention, the plaintext data received from the application system in the information terminal device is stored in a plurality of blocks in the security area. The encryption key generation with the same feature is performed in accordance with the number of blocks of the plurality of plaintext data after the division, and the creation of the encrypted data with the same feature corresponds to the plurality of encryption keys after the generation, respectively. The present invention employs a configuration of a data encryption method for performing encryption processing on a plurality of divided plaintext data by using a plurality of encryption schemes that function as a plurality.

A third feature of the method of the present invention resides in that the plaintext data received from the application system in the information terminal device is divided into a plurality of blocks at an arbitrary length in the second feature of the method of the present invention. An aspect of the present invention resides in adoption of a configuration of a data encryption method for storing a plurality of encrypted data after encryption processing in a feature in an external area of a security area by adding block length data to each of the plurality of encrypted data.

A fourth feature of the method of the present invention is that the plaintext data received from the application system in the information terminal device is divided into a plurality of blocks for each fixed length in the second feature of the method of the present invention. A configuration of a data encryption method for storing a plurality of encrypted data after encryption processing in the feature in an external area of the security area by adding padding data to specific encrypted data having a length less than the fixed length is adopted. It is in.

The fifth feature of the method of the present invention is that the correspondence between the plurality of encryption keys and the plurality of encryption methods in the second, third, or fourth feature of the method of the present invention is determined by the plurality of encryption methods after the encryption processing. The present invention resides in adopting a configuration of a data encryption method for storing in a security area together with a divided block number assigned to encrypted data.

A sixth feature of the method of the present invention is that when storing the correspondence between the plurality of encryption keys and the plurality of encryption methods in the above-described fifth feature of the method of the present invention, the plurality of encryption keys should be made to correspond to the functions. The present invention resides in adopting a configuration of a data encryption method for selecting a plurality of encryption methods in accordance with a user's instruction.

A seventh feature of the method of the present invention is that when storing the correspondence between the plurality of encryption keys and the plurality of encryption methods in the above-described fifth feature of the method of the present invention, the plurality of encryption keys should correspond to the respective functions. The present invention resides in adopting a configuration of a data encryption method for randomly selecting a plurality of encryption methods.

An eighth feature of the method of the present invention resides in that the security area in the first, second, third, fourth, fifth, sixth or seventh feature of the above-described method of the present invention is formed by a one-chip device. In this case, the data encryption method having a functional configuration according to the present invention is adopted.

A ninth feature of the method of the present invention resides in that the external device according to the first, second, third, fourth, fifth, sixth, seventh or eighth feature of the method of the present invention is connected to a computer card. In this case, the data encryption method having a functional configuration according to the present invention is adopted.

On the other hand, the first feature of the device of the present invention is that an external device capable of mutually transmitting and receiving data to and from an application system mounted on an information terminal device, and a setting inside the external device. Security area, encryption key generation means for generating a required encryption key using random numbers in the security area, and encryption key storage means for storing the encryption key generated by the encryption key generation means in the security area And an encryption method storage means for storing in advance in the security area, an encryption method that functions in accordance with the encryption key generated by the encryption key generation means, and information using the encryption method stored in the encryption method storage means. Encrypted data creation means for creating encrypted data by performing encryption processing on the plaintext data received from the application system in the terminal device in the security area, and created by the encrypted data creation means The in the configuration adopting the data encryption apparatus having the encrypted data storing means for storing in the external area of the security region the encrypted data.

A second feature of the apparatus of the present invention is that, in addition to the first feature of the above-described apparatus of the present invention, plaintext data division for dividing plaintext data received from an application system in an information terminal into a plurality of blocks in a security area. Means for generating a plurality of encryption keys according to the number of blocks of the plurality of plaintext data obtained by the plaintext data dividing means, wherein the encryption key storage means for the same feature comprises: A plurality of cryptographic keys generated by the cryptographic key generating means are stored, and a plurality of cryptographic schemes having the same characteristics function in correspondence with the plurality of cryptographic keys generated by the cryptographic key generating means. Are respectively stored in advance, and the encrypted data creating means having the same feature uses the plurality of encryption schemes stored in the encryption scheme storage means to store a plurality of encrypted A data encryption device that performs encryption processing on text data to create a plurality of encrypted data, and an encrypted data storage unit having the same feature stores a plurality of encrypted data created by the encrypted data creation unit. Configuration adoption.

A third feature of the present invention is that the plaintext data dividing means in the above second feature of the present invention divides plaintext data received from an application system in the information terminal into a plurality of blocks of arbitrary length. An encrypted data storage means having the same feature is characterized by adopting a configuration of a data encryption device for adding block length data to each of a plurality of encrypted data created by the encrypted data creation means and storing the same.

A fourth feature of the present invention is that the plaintext data dividing means in the above second feature of the present invention divides plaintext data received from an application system in the information terminal into a plurality of fixed-length blocks. A data encryption unit configured to add padding data to specific encrypted data less than the fixed length among a plurality of encrypted data created by the encrypted data creating unit and storing the encrypted data; Lies in the configuration of the gasifier.

A fifth feature of the device of the present invention is that, in addition to the second, third or fourth feature of the device of the present invention, encryption information indicating the correspondence between a plurality of encryption keys and a plurality of encryption methods is provided. Another aspect of the present invention resides in the adoption of a configuration of a data encryption device further including an encryption information storage means for storing in a security area together with a divided block number assigned to a plurality of encrypted data.

A sixth feature of the device of the present invention resides in that the encryption information storage means in the fifth feature of the above-described device of the present invention allows a user to specify a plurality of encryption methods to be associated with a plurality of encryption keys. The present invention is to adopt a configuration of a data encryption device that stores encryption information based on a result selected accordingly.

A seventh feature of the device of the present invention resides in that the encrypted information storage means in the fifth feature of the device of the present invention randomly selects a plurality of encryption methods to be associated with a plurality of encryption keys. In the configuration of a data encryption device that stores encryption information based on the

An eighth feature of the device of the present invention is that the security area in the first, second, third, fourth, fifth, sixth or seventh feature of the device of the present invention is a one-chip element. And a data encryption device having a functional configuration according to the present invention.

A ninth feature of the device of the present invention is that the external device according to the first, second, third, fourth, fifth, sixth, seventh or eighth feature of the device of the present invention is a computer card. And a data encryption device having a functional configuration according to the present invention.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below with reference to the accompanying drawings with reference to examples of apparatuses and methods.

(Example of Apparatus) First, as shown in FIG. 1, an entire system of a data encryption apparatus according to the present embodiment is connected to an application system 12 mounted on an information terminal apparatus 11 by an I / F (interface). ) An external device 14 capable of alternately transmitting and receiving data to and from the application system 12 is connected via software via a portion 13. The application system 12 does not have an encryption function in itself, and the function is borne by an external device 14 connected to the application. That is, the application system 12 according to the present embodiment transfers the plaintext data Df11 input to the information terminal device 11 to the external device 14 via the I / F 13 or transmits / receives the plaintext data Df11 from the external device 14 to the I / F1.
3 only has a function of outputting the plaintext data (restoration) Dd11 passed through the external device 3 to the outside.

The external device 14 includes therein a security unit 15 which is an area where physical security is possible. The security unit 15 further includes an encryption key K.
It comprises an encryption key storage unit 16 for storing cd11. In addition, the external device 14 includes an encrypted data storage unit 17 for storing the encrypted data Dc11. The above-described required encryption function includes an operation of performing encryption processing Pc11 on the plaintext data Df11 passed from the application system 12 to obtain encrypted data Dc11 inside the security unit 15, and an operation of obtaining the encrypted data Dc11. The operation of delivering the plaintext data (restoration) Dd11 obtained by applying the decryption process Pd11 to Dc11 to the application system 12 is achieved by using the encryption key Kcd11.

The above-mentioned external device 14 can be functionally constituted by a computer card inserted into a dedicated card slot (not shown) of the information terminal device 11, for example. The computer card has excellent characteristics of portability and is always under the control of the user. Therefore, it can be said that the computer card is extremely useful from the viewpoint of preventing leakage of the encryption key Kcd11 and the encrypted data Dc11.

In order to obtain the above-described functional configuration, first, as shown in FIG. 2, a security section 22 (equivalent to the security section 15 shown in FIG. The control unit 23 controls the overall operation of the computer card 21, and the encryption / decryption unit that actually performs the encryption process Pc11 and the decryption process Pd11 to create the encrypted data Dc11. 24 and the encryption key K
a random number generator 25 that generates a random number used to generate cd11;
An encryption method storage unit 26 (which will be described in detail later) that stores an encryption method that functions in accordance with the generated encryption key Kcd11, and an encryption key storage unit 27 (which will be described in detail later) that stores the generated encryption key Kcd11. , An encryption information storage unit 28 (which will be described in detail later) that stores encryption information indicating the correspondence between the encryption key Kcd11 and the encryption method, and an I / F 29 that interfaces with the outside.
Are provided.

In addition to the above components, an encrypted data storage unit 30 for storing the created encrypted data Dc11 is provided in an area outside the security protection unit 22 in the computer card 21, and an information terminal device. A terminal input / output control unit 31 for controlling input / output (data transmission / reception) between the computer card 11 and the computer card 21 is provided.

The control unit 23 in the security unit 22
It also has a function of dividing the plaintext data Df11 received from the application system 12 in the information terminal device 11 through the terminal input / output control unit 31 and the I / F 29 into a plurality of blocks of arbitrary length or fixed length. Here, the plurality of plaintext data after the division are respectively represented as “A”, “B”, and “C” (in the case of three divisions. These symbols are also used in the following description). , A plurality of plaintext data A, B, and C after the division using different encryption methods, and a plurality of corresponding encrypted data A ′, B ′,
If C 'is created, the strength against decryption by a third party can be greatly improved compared to the related art.

For this reason, as shown in FIG. 3, a plurality of plaintext data A, B,
A plurality of encryption methods A, B, and C corresponding to the number of blocks of C
Encryption method ID (identifier): algA, algB, a
It is stored in advance together with lgC. In response to this,
A plurality of encryption keys aaaaaaaa, bbbbbb corresponding to the number of blocks of the plurality of plaintext data A, B, and C after the division (sufficient to make the plurality of encryption methods A, B, and C respectively function).
bb and cccccccc are randomly generated by the control unit 23 and the random number generation unit 25. These are, as shown in FIG.
An encryption key ID (identifier) is stored in the encryption key storage unit 27:
It is stored together with keyA, keyB, and keyC.

As shown in FIG. 5, the encryption information storage unit 28 shows the correspondence between the above-mentioned plurality of encryption keys A, B, and C and the plurality of encryption systems A, B, and C. The encryption information to be used for the search in the decryption process Pd11 of the encrypted data Dc11 is stored together with the divided block numbers (details will be described later) assigned to the plurality of encrypted data A ', B', and C '. It has become. At this time, a plurality of encryption keys A,
The selection of a plurality of encryption methods A, B, and C to be made to correspond to the functions of B and C, respectively, may be performed by instructing a user (user), or the function of the random number generation unit 25 is used. For example, it may be performed at random.

The above-mentioned divided block number is sequentially assigned to each header portion of a plurality of encrypted data A ', B', and C 'which are finally created, as shown in FIG. The plurality of encrypted data A ', B', and C 'to which the divided block numbers are assigned are in accordance with the data order of the original plaintext data Df11 (that is, in the order of the divided block number numbers). They are arranged again and stored collectively in the encrypted data storage unit 30. At this time, in the control unit 23, the received plaintext data Df1
When 1 is divided into a plurality of blocks of arbitrary length, the block length data (not shown) of each of the generated encrypted data A ', B', C 'is added immediately after each divided block number. When the encrypted data is stored in the encrypted data storage unit 30 and divided into a plurality of blocks of a fixed length, the specified encrypted data A ', B', and C ', which are less than the fixed length, are specified. It is preferable that padding data (not shown) is added to the encrypted data and stored.

As described above, the data encryption device according to the embodiment of the present invention has been described as an example. However, the security section 22 in the computer card 21 described above uses its corresponding individual components to correspond to each component. Although it can be configured, it may be configured by a one-chip element integrating these functions. When this one-chip element configuration is employed, the security unit 22 is completely black-boxed, which is advantageous in obtaining an area where physical security can be secured.

(Example of Method) Next, a description will be given of an implementation procedure of an example of a method applied to the above-described apparatus example.

First, the encryption method in the data encryption method according to the present embodiment will be described with reference to FIG.
As shown in the figure, the plaintext data Df11 is converted to the encrypted data Dc1.
In order to obtain 1, as described in the previous example of the apparatus, different encryption methods A (for two divisions) are obtained for each of the plurality of plaintext data A and B (in the case of two divisions) obtained by dividing the plaintext data Df11 into a plurality of blocks. Af11) and B (Af12) and the corresponding encryption keys Kcd11 and Kcd12 are used to perform encryption Pcc11 and Pcc12, respectively, so that a plurality of corresponding encrypted data A 'and B' are created. .

The above process will be specifically described in relation to the above-described apparatus example. First, as shown in FIG.
The plaintext data Df11 passed from the application system 12 in the information terminal device 11 is received by the terminal input / output control unit 31 in the computer card 21 (ST1), and the received plaintext data Df11 is stored in the security unit 22. Control unit 2
3 and is divided into a plurality of blocks of arbitrary length, that is, a plurality of plaintext data A, B, and C (in the case of three divisions) (ST2).

It should be noted that the division of the plaintext data Df11 into a plurality of blocks performed here does not necessarily need to be divided into three as shown in the example, but may be divided into any other number of blocks. Further, as described above, instead of dividing the received plaintext data Df11 into a plurality of blocks of an arbitrary length, a method of dividing the received plaintext data Df11 into a plurality of blocks of a fixed length may be adopted.

Next, when a plurality of plaintext data A, B, and C are obtained by the control unit 23, a random number is generated by the random number generation unit 25 under the control of the control unit 23, and the generated random number is used. , A plurality of encryption keys aaaaa corresponding to the number of blocks of the plurality of plaintext data A, B, and C after division.
aaa, bbbbbbbb, and cccccccc are generated (ST3), and these are respectively encrypted key IDs: k as shown in FIG.
It is stored in the encryption key storage unit 27 together with eyA, keyB, and keyC.

Next, a plurality of required encryption keys aaaaaaaa, bb
When bbbbbb and cccccccc are generated, the encryption system storage unit 26 shown in FIG. B and C are
Encryption method IDs corresponding to these: algA, algB, alg
Along with C, it is selected according to the user's instruction or randomly (ST4).

When the plurality of encryption methods A, B, and C are selected in accordance with a user's instruction, the instruction is input from a keyboard (not shown) of the information terminal device 11. Is performed at random, a random number may be generated by the random number generation unit 25 in the computer card 21.

When the above processing is completed, the encryption / decryption unit 24 actually performs the encryption processing Pc11 (ST5). For example, the encryption key aaaaaaaa (keyA)
Is performed using the encryption method A (algA) while using the encryption method A (algA (keyA [A])) in the figure. The same applies to notations related to.

Finally, when the above-described encryption processing Pc11 is performed, the required encryption data Dc11 including a plurality of encryption data A ', B', and C 'is created in the control unit 23 (ST6). Further, here, encryption information to be used for retrieval at the time of the decryption processing Pd11 of the encrypted data Dc11 is also created, and this is stored in the encryption information storage unit 28 in the form shown in FIG. ST7) The previously created encrypted data Dc11 is collectively stored in the encrypted data storage unit 30 in the form shown in FIG. 6 (ST8).

That is, in the above-described series of processing from ST6 to ST8, the control unit 23 sequentially assigns the divided block number to each header portion of the plurality of encrypted data A ', B', and C 'created in the preprocessing. And these are the original plaintext data D
They are arranged again in accordance with the data order of f11, and are collectively stored in the encrypted information storage unit 28 as required encrypted data Dc11. At this time, in the process of ST2 described above,
When the plaintext data Df11 is divided into a plurality of blocks of an arbitrary length, the block length data of each of the encrypted data A ', B', and C 'is added immediately after each of the divided block numbers. When the data is divided into padding data, padding data is added to specific encrypted data less than the fixed length among the encrypted data A ', B', and C '.

As a result, instead of the conventional simple encrypted data (Dc1) using one kind of fixed encryption system as shown in FIG. 10, various encrypted data using a plurality of encryption systems are used. Dc11 can be obtained, thereby realizing a cryptographic system with extremely high confidentiality that is not easily deciphered by, for example, collection of information by a third party. In addition, the process for obtaining the encrypted data Dc11 does not include the repetitive process as shown in FIG.
It is possible to create the encrypted data Dc11 in substantially the same time as the process in the encryption method shown in (1). For example, even when the encrypted data Dc11 is used for network transmission, the data transmission speed is reduced. This is extremely advantageous.

Although the embodiments of the present invention have been described with reference to the example of the apparatus and the example of the method, the present invention is not necessarily limited to the above-described means and methods, and achieves the object of the present invention. Within the range having the effects described below,
Changes can be made as appropriate.

[0060]

As described above, according to the present invention,
An encryption key is generated and encrypted / decrypted in a secure area set in an external device such as a computer card, and the obtained encrypted data is stored in the external device. When not in use, it is possible to remove the external device from the information terminal device and carry it at all times. As a result, the risk of leakage of the encryption key or the risk of theft or erasure of the encrypted data is greatly increased. Will decrease.

Further, the encrypted data is created in accordance with a user's instruction or by using a plurality of encryption methods selected at random, and the encrypted information at this time is stored in a security area set in the external device. So, for example,
It is impossible for a person or the like who tries to use the cryptographic system illegally to determine which part of the encrypted data is created using which encryption method, and as a result, Will be dramatically improved.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a data encryption device according to an embodiment of the present invention.

FIG. 2 is an internal block diagram of a computer card as an example of a functional configuration of the external device shown in FIG.

FIG. 3 is a configuration diagram of each data stored in an encryption method storage unit illustrated in FIG. 2;

FIG. 4 is a configuration diagram of each data stored in an encryption key storage unit shown in FIG. 2;

FIG. 5 is a configuration diagram of each data stored in an encryption information storage unit shown in FIG. 2;

FIG. 6 is a configuration diagram of each data stored in an encrypted data storage unit shown in FIG. 2;

FIG. 7 is a conceptual diagram of an encryption method in a data encryption method according to an embodiment of the present invention.

FIG. 8 is a flowchart showing a procedure of a data encryption method according to an embodiment of the present invention.

FIG. 9 is a configuration diagram of a conventional encryption system.

FIG. 10 is a conceptual diagram of a conventional encryption method applied to the encryption system shown in FIG.

11 is a conceptual diagram of an encryption method obtained by improving the conventional method shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Information terminal device 12 ... Application system 13 ... I / F (interface) 14 ... External device 15 ... Security protection part 16 ... Encryption key storage part 17 ... Encrypted data storage part 21 ... Computer card 22 ... Security protection part 23 ... Control unit 24 ... Encryption / decryption unit 25 ... Random number generation unit 26 ... Encryption method storage unit 27 ... Encryption key storage unit 28 ... Encryption information storage unit 29 ... I / F (interface) 30 ... Encryption data storage unit 31 ... Terminal Input / output control unit Df11: plain text data Dc11: encrypted data Dd11: plain text data (restoration) Kcd11, Kcd12: encryption key Pc11: encryption process (process) Pd11: decryption process (process) Pcc11, Pcc12: encryption (process) Af11 , Af12 ... encryption method (encryption algorithm A, B)

Claims (18)

[Claims] An external device capable of mutually transmitting and receiving data to and from an application system mounted on an information terminal device is used. In a security area set inside the external device, required A cryptographic key is generated using a random number, and plaintext data received from an application system in the information terminal device is subjected to cryptographic processing by using a cryptographic method that functions in accordance with the generated cryptographic key, thereby generating encrypted data. Wherein the generated encryption key is stored in the security area, and the generated encrypted data is stored in an area outside the security area. 2. Prior to generation of the encryption key, the plaintext data received from an application system in the information terminal device is divided into a plurality of blocks in the security area, and the generation of the encryption key is performed after the division. Is performed according to the number of blocks of the plurality of plaintext data.
2. The data encryption method according to claim 1, wherein encryption processing is performed on each of the plurality of plaintext data after the division. 3. The division of the plaintext data received from the application system in the information terminal device into a plurality of blocks is performed at an arbitrary length, and the plurality of encrypted data after the encryption processing is outside the security area. The data encryption method according to claim 2, wherein the storage in the area is performed by adding block length data to each of the plurality of encrypted data. 4. The division of the plaintext data received from the application system in the information terminal device into a plurality of blocks is performed for each fixed length, and the plurality of encrypted data after the encryption processing is outside the security area. The data encryption method according to claim 2, wherein the storage in the area is performed by adding padding data to the specific encrypted data having a length less than the fixed length. 5. The security relationship between the plurality of encryption keys and the plurality of encryption methods is stored in the security area together with a divided block number assigned to the plurality of encrypted data after the encryption processing. The data encryption method according to claim 2, 3, or 4. 6. When storing the correspondence between the plurality of encryption keys and the plurality of encryption methods, selection of the plurality of encryption methods to be functionally associated with the plurality of encryption keys in accordance with a user's instruction. The method according to claim 5, wherein the method is performed. 7. The method according to claim 1, wherein, when storing the correspondence between the plurality of encryption keys and the plurality of encryption methods, the plurality of encryption methods to be functionally associated with the plurality of encryption keys are selected at random. The data encryption method according to claim 5, wherein 8. The security area according to claim 1, wherein said security area is functionally constituted by a one-chip element.
Data encryption method described in 1. 9. The data encryption method according to claim 1, wherein the external device has a function configured by a computer card. 10. An external device capable of mutually transmitting and receiving data to and from an application system mounted on an information terminal device, a security area set inside the external device, and a required encryption. Encryption key generation means for generating a key in the security area using random numbers; encryption key storage means for storing the encryption key generated by the encryption key generation means in the security area; and encryption key generation means An encryption method storage means for storing in advance in the security protection area an encryption method functioning in correspondence with the encryption key generated in the above, and the information terminal device using the encryption method stored in the encryption method storage means Means for encrypting the plaintext data received from the application system in the security area to create encrypted data; and generating the encrypted data. Having an encrypted data storage means for storing the encrypted data created by the step in the outer region of the security area, the data encryption apparatus characterized by. 11. A plaintext data dividing unit for dividing the plaintext data received from an application system in the information terminal device into a plurality of blocks in the security area, wherein the encryption key generating unit includes the plaintext data dividing unit. Means for generating a plurality of encryption keys in accordance with the number of blocks of the plurality of plaintext data obtained by the means, wherein the encryption key storage means stores the plurality of encryption keys generated by the encryption key generation means, The encryption method storage means stores in advance a plurality of encryption methods which correspond to the plurality of encryption keys generated by the encryption key generation means, respectively, and the encrypted data creation means stores the encryption method storage means in the encryption method storage means. Using the plurality of stored encryption methods, the plurality of plaintext data obtained by the plaintext data dividing means are respectively subjected to encryption processing to create a plurality of encrypted data. The data encryption device according to claim 10, wherein the encrypted data storage unit stores the plurality of encrypted data created by the encrypted data creation unit. 12. The plaintext data dividing unit divides the plaintext data received from an application system in the information terminal device into a plurality of blocks of an arbitrary length, and the encrypted data storage unit includes the encrypted data creating unit. The data encryption device according to claim 11, wherein block length data is added to each of the plurality of encrypted data created in (1) and stored. 13. The plaintext data dividing unit divides the plaintext data received from an application system in the information terminal device into a plurality of fixed-length blocks, and the encrypted data storage unit includes the encrypted data creating unit. The data encryption apparatus according to claim 11, wherein padding data is added to specific encrypted data having a length less than the fixed length among the plurality of encrypted data created in (1) and stored. 14. Encryption information for storing, in the security area, encryption information indicating a correspondence between the plurality of encryption keys and the plurality of encryption schemes, together with a divided block number assigned to the plurality of encrypted data. 14. The data encryption device according to claim 11, further comprising a storage unit. 15. The encryption information storage means stores the encryption information based on a result of selecting the plurality of encryption systems to be made to correspond to the plurality of encryption keys in accordance with a user's specification. The data encryption device according to claim 14, wherein: 16. The encryption information storage means stores the encryption information based on a result of randomly selecting the plurality of encryption schemes to be made to correspond to the plurality of encryption keys, respectively. The data encryption device according to claim 14, wherein: 17. The security area according to claim 10, wherein the security area is functionally constituted by a one-chip element.
17. The data encryption device according to 4, 15, or 16. 18. The apparatus according to claim 10, wherein said external device has a function configured by a computer card.
The data encryption device according to 1, 12, 13, 14, 15, 16 or 17.