JPH103431A - Secret information storage method and system - Google Patents

Abstract

(57) [Summary] [Problem] To increase secret information managed by a user, and eliminate the need for conventional processing between a center and a user based on authentication. A user has a physical protection processing mechanism and an auxiliary storage device. The processing mechanism 100 uses the key L
Keep K secret and physically secure. When storing the message M, the processing mechanism 100 generates a key DK for each message, outputs information eLK (DK) obtained by encrypting the DK with LK, and outputs information eDK obtained by encrypting M with DK.
(M) is output. The auxiliary storage device 200 stores the encrypted information eLK (DK) and eDK (M). At the time of message retrieval, the processing mechanism 100 inputs eDK (DK) and eDK (M) from the storage device 200,
K is decoded, the message M is decoded by the DK, and the message M is given to the processing unit 130.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method and system for storing secret information, which enables a device with a small memory capacity to use a seemingly confidential large-capacity information.

[0002]

2. Description of the Related Art With the development of an electronic information society, prepaid cards and credit cards have become widespread. In the future, ID cards such as licenses containing personal electronic information, and the value of money as electronic information It is expected that an electronic cash system will be introduced. Thus, the opportunity for individuals to carry confidential information that must be kept secret from others increases.

Conventionally, it has been sufficient to store important information in a database of a center device and strictly control who can access it. However, electronic cash stores some kind of important information in personal belongings. Need arises. Further, as ID cards become more widespread, the chances of being used for confirmation means other than the intended purpose increase, and the need to accumulate personal use histories increases. In addition, it is necessary to cope with a case where it is preferable that an individual has a large amount of secret data for management. For example, management of radiographic information of individuals in the medical field.

FIG. 4 shows a conventional management system based on authentication. Here, C is a secret key (challenge) of the center, and K is a secret key for user confirmation that differs for each user. The user device 420 is limited to a function of authenticating the validity of the user to the center device 410, receives the challenge C from the center device 410, and
In step 2, the challenge C is decrypted with the key K, and a response R as an output result is returned to the center device 410. In the center unit 410, the decoding unit 412 sends the response R
Is encrypted with the key K corresponding to the user,
In the above, it is confirmed whether or not the original challenge C is decrypted, and if it is determined to be valid, a process based on the user's request is executed.

However, in the case of this conventional method, the key K of the user is also known to the center, so that if the management of the center device is poor, it may be possible to access the personal information of the user.

In the description of FIG. 4, a description has been given on the assumption that the key to be decrypted and the key to be encrypted are the same secret key cryptosystem.
There is a public key cryptosystem. That is, the key K of the center user is a public key PK, and the key K of the user is a secret key SK. Due to the nature of public key cryptography, PK to SK
Is difficult to calculate by analogy, so that the problem of the center device does not occur.

[0007] However, in the case of a public key encryption method such as the RSA method, which is generally used, the amount of decryption processing dK increases. Originally, it is assumed that the user carries the card, and the device is inexpensive and has only a small amount of processing.

[0008] Further, although the individual should be managed by the individual, the user device does not have a storage means, so that the center device may store a large amount of data which does not need to be stored, which may be uneconomical. .

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to mainly manage the right to access confidential information by expanding the amount of confidential information that the user has to handle and manage in the prior art. This eliminates the need for authentication-based processing that has been introduced for the purpose, and as a result, eliminates the need for public key encryption processing that may be required for management between the center device and the user device. .

[0010]

FIG. 1 is a conceptual diagram of the present invention. According to the present invention, the user can use the physical protection processing mechanism 100.
And the auxiliary storage device 200. The physical protection processing mechanism 100 includes encryption / decryption units 110 and 120,
In addition to the processing unit 130, the key LK is kept secret and physically secure. The auxiliary storage device 200 includes a storage device 210, stores information (encrypted information) input from the physical protection processing mechanism 100, and reads out (extracts) the encrypted information from the physical protection processing mechanism 100. Processing is performed.

In the physical protection processing mechanism 100, a message M as secret information which must be kept secret as a whole is encrypted by an encryption / decryption unit 120 using a key DK corresponding to the message. Storage device 2
00 is stored in the storage device 210. Further, the key DK is encrypted by the encryption / decryption unit 110 using the key LK which is securely held, and the encrypted message information eDM
It is stored in the storage device 210 together with (M). FIG.
(A) shows this. Here, the message M
May be externally provided to the physical protection processing mechanism 100, or may be generated in the auxiliary storage device 200 and provided to the physical protection processing mechanism 100.

When decrypting an encrypted message,
The associated encrypted key information eLK (DK) is read from the storage device 210 of the auxiliary storage device 200 together with the encrypted message information eDK (M). In the physical protection processing mechanism 100, first, the encryption / decryption unit 110 encrypts the encrypted key information e with the key LK held securely.
LK (DK) is decrypted to obtain key DK, and then encrypted /
The message key information e encrypted by the decryption unit 120
DK (M) is decrypted with the key DK to obtain a message M. The output result of the encryption / decryption unit 120 is input to the processing unit 130 and is subjected to a desired process. FIG.
(B) illustrates this. Here, what is created from the message M is arbitrary.

In FIG. 1, the encryption and decryption required on the way are processed in the physical protection processing mechanism 100, and the result on the way cannot be observed. Although only the input / output result can be observed from the outside, security can be ensured due to the nature of the encryption algorithm employed. In addition, when the key DK is randomly generated and the decrypted message M is also processed and output afterwards, since the observed input information is small,
Since only the output information is known, a cipher suitable for a ciphertext alone attack may be selected.

As described above, the present invention utilizes an auxiliary storage device having a storage device that can be handled by an individual, and a physical protection processing mechanism that locally stores secret information based on physical security. Thus, while the physical protection processing mechanism can be realized with a simple configuration, the auxiliary storage device does not have a specialized secret information processing function, and therefore can be realized by general-purpose components. Further, the physical protection processing mechanism can be composed of only a secret key cryptographic processing function in terms of arithmetic processing, so that the processing is simple. Here, as the physical protection processing mechanism, an IC card can be assumed to be available. It is effective when it is assumed that it is difficult to analyze an IC loaded on a card with ordinary technical capabilities. On the other hand, since the auxiliary storage device can use general-purpose components as a memory, a small computer such as a personal computer equipped with a hard disk or the like can be assumed.

[0015]

FIG. 2 is a block diagram showing an embodiment of the present invention. In FIG. 2, the physical protection processing mechanism 10
0 is an encryption / decryption unit 11 also used for a key message
0, a processing unit 130, a key holding unit 140 in which the key LK is kept secretly and physically securely, and a key including a random number generator that generates a key DK for changing each time the message M changes. It comprises a generator 150 and selectors 160 and 170. The encryption / decryption unit 11 is selected by the selection unit 160.
With the output of 0, either LK or DK is selected. In addition, the selector 170 controls the encryption / decryption unit 110
Of the message M, the generated key DK, or an external device such as the auxiliary storage device 200 is selected. The output of the encryption / decryption unit 110 is output from the outside of the auxiliary storage device 200 or to the processing unit 130. Auxiliary storage device 20
0 has a storage device 210 for storing the encrypted message eDK (M) and the associated encrypted key eLK (DK).

FIG. 3 shows a flowchart of the entire process in FIG. Hereinafter, description will be made in accordance with this.

Initial setting 310 of the physical protection processing mechanism; whether it is written externally or given a random value,
The key LK is safely stored in the key holding unit 140. On the other hand, the message M to be processed is already generated or introduced from outside.

Process 320 in the physical protection processing mechanism; a key DK is generated by a key generator 150 such as a random number device. Then, first, the key LK and the key DK are input to the encryption / decryption unit 110 through the selector 160, and the encryption / decryption unit 110 encrypts the DK with the LK to obtain the key encryption information eLK (DK )
Is output. Next, the message M and the key DK are selected by the selector 17.
0 is input to the encryption / decryption unit 110, and the encryption / decryption unit 110 encrypts M with DK and outputs message encryption information eDK (M).

Auxiliary storage device storage processing 330; storage device 2
10 stores the key encryption information eLK (DK) output from the physical protection processing mechanism 100 and the message encryption information eDK (M).

Auxiliary storage device reading process 340: The key encryption information eLK (DK) and the message encryption information eDK (M) are read from the storage device 210 and output to the physical protection processing mechanism 100.

Process 350 in the physical protection mechanism: The key encryption information eLK (DK) and the message encryption information eDK (M) from the auxiliary storage device 200 are input to the encryption / decryption unit 110 through the selector 17. Further, the key LK of the key holding unit 140 is transmitted to the encryption / decryption unit 110 through the selector 160.
Enter In the encryption / decryption unit 110, first, LK
Decrypts the eLK (DK) and sets the decrypted key DK as a key for the next decryption process. Next, this DK uses eD
K (M) is decoded, and the decoded message M is output or given to the processing unit 130. The processing unit 13
What is done at 0 is an application of the present invention and is not directly related to the present invention and will be omitted.

Here, it is assumed that users access each other via the Internet, for example, using the auxiliary storage device 200 as a personal computer. In this case, it is impossible to read the content of the message M that requires secret since it is encrypted. Also, the physical protection processing mechanism 10
Although an IC card is generally used as 0, the security is guaranteed because the key LK is physically and completely kept secret and only the input / output result can be observed from the outside.

[0023]

As described above, according to the present invention, the amount of secret information handled and managed by the user can be increased, and in particular, the conventional method based on authentication between the center and the user becomes unnecessary. .

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of the present invention.

FIG. 2 is a configuration diagram of one embodiment of the present invention.

FIG. 3 is a processing flowchart of FIG. 2;

FIG. 4 is a schematic diagram of a conventional method based on authentication.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 Physical protection processing mechanism 110, 120 Encryption / decryption unit 130 Processing unit 140 Key storage unit 150 Key generator 160, 170 Selector 200 Auxiliary storage device 210 Storage device

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location H04L 9/00 641

Claims (2)

[Claims] 1. A secret information storage method using a physical protection processing mechanism and an auxiliary storage device, wherein a key LK is secretly and physically securely stored in the physical protection processing mechanism, The physical protection processing mechanism generates a key DK for the secret message M to be processed, encrypts the generated key DK with the key LK, and outputs key encryption information eLK (DK). , The generated key D
K to output the message encryption information eDK (M) by encrypting the message M, and the auxiliary storage device stores the key encryption information eLK (DK) and the message encryption information output from the physical protection processing mechanism. When reading out the message, the physical protection processing mechanism inputs the key encryption information eLK (DK) and the message encryption information eDK (M) from the auxiliary storage device. ,
A method for storing secret information, comprising: decrypting the eLK (DK) with the key LK to obtain a key DK; decrypting the eDK (M) with the decrypted key DK; and outputting a message M. 2. A secret information storage system comprising a physical protection processing mechanism and an auxiliary storage device, the physical protection processing mechanism comprising: a key holding unit for physically holding a key LK in secret; Key generation means for generating the key DK of
The generated key DK is encrypted with the key LK to output key encryption information eLK (DK), and the message M is encrypted with the generated key DK to output message encryption information eDK (M). And the key encryption information eLK (DK) and the message encryption information eDK (M).
(DK), and decrypts the eDK with the decrypted key DK.
(M) decrypting means for decrypting the message M, and processing means for processing the message M, wherein the auxiliary storage device stores the key encryption data output by the physical protection processing mechanism. Information eLK (DK) and the message encryption information eDK (M) are input and stored, and storage means is provided for outputting the stored encryption information to the physical protection processing mechanism. Secret information storage system.