JPH10214026A - Electronic signature method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To flexibly control the complicatedness of a signature. SOLUTION: Signature object information is sectioned by 128 bits and exclusively ORed (XOR) to obtain 120-bit modified information X (S2), and logical operations f(X,Y)=(=X+T), g(X,Y)(=X XOR Y) including X and secret information Y on this signer as variables are found to generate pieces of initial information f(X,Y) and g(X,Y) (S4). Then g(X,Y) is stored in a work area and the other f(X,Y) is sectioned by 4 bit in order and decoded into decimal numbers to generate operation sequences... (S6). Then logical operations corresponding to respective numerals of the operation sequences are performed for f(X,Y) on the basis of a predetermined numeral and logical operations (left shift, right shift, OR between high-order and low-order halves,...) to generate (S8, S9) signature information, and the sum of this information and signature object information is sent out (S10).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for a signer to digitally sign information to be signed.

[0002]

2. Description of the Related Art A conventional digital signature method will be described with reference to FIG. The signer's secret information is stored in the secret information storage unit 11 in advance, and when performing the signature, the control unit 12 reads out the signature target information from the signature target information storage unit 13 such as the contents of mail, The modified signature target information generation unit 14 to be supplied to the information generation unit 14 generates information for signature (modified signature target information), for example, 128-bit information generated from the entire signature target information. For this generation, for example, modified signature target information is obtained by dividing the signature target information in units of 128 bits and taking an exclusive OR of them. In this way, it is possible to realize a method in which the modified signature target information after generation changes even if any one bit changes.

[0003] The modified signature target information is sent to the signature unit 15. The signature unit 15 reads the secret information stored in the secret information storage unit 12, and generates signature information based on the secret information and the modified signature target information. This generation is realized by encrypting the modified signature target information by using a secret information as a key by a predetermined encryption algorithm. The signature information and the signature target information are transmitted from the communication processing unit 16 via the network 17. Only the recipient who knows the signer's secret information can verify the validity of the signature.

[0004]

The conventional digital signature method uses an encryption method, and the processing is complicated, and the complexity cannot be changed to a simple signature or an advanced signature. In addition, the length of the originally designed information is restricted, and it is impossible to process other information having a length. Also, since a method such as encryption is used, there is a disadvantage that a network programming language that transfers and implements a logical operation operation over a network is slow.

[0005]

According to the first aspect of the present invention, the information to be signed and the secret information (of the signer) are mutually processed to generate a plurality of different pieces of initial information.
Is divided into sections of a predetermined number of bits, and each section is converted into a logical operation operation according to the content thereof to obtain an operation sequence, and each operation of the operation sequence is sequentially performed on the rest of the plurality of initial information. To obtain signature information.

According to the second aspect of the present invention, the information to be signed and the secret information are mutually processed to generate at least one piece of initial information, and the predetermined information is determined in advance from the initial information and at least one of the information to be signed and the secret information. The selected one is divided into sections of a predetermined number of bits, and each section is converted into a logical operation operation according to the content thereof to obtain an operation sequence. In order to obtain signature information.

According to the fourth aspect of the present invention, one of the signature target information and the secret information is divided into sections of a predetermined number of bits, and each section is converted into a logical operation operation according to the content to form an operation sequence. Then, the converted logical operation operations are sequentially performed on the other of the signature target information and the secret information to obtain signature information. Further, a pseudo random number is generated, and the pseudo random number is included in the generation of the initial information, or the pseudo random number is included in the logical operation operation, and the random number is added to the signature information.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The functional configuration of an electronic signature apparatus to which the embodiment of the first aspect of the present invention is applied is shown by attaching the same reference numerals to parts corresponding to those in FIGS. In this embodiment, the secret information in the secret information storage unit 11 and the deformed signature target information are processed with each other to generate a plurality of different initial information in the initial information generation unit 21, and the initial information is stored in the work information storage unit 22.
Is stored, and the one piece of initial information is divided into sections of a predetermined number of bits, and each of the divided sections is determined in advance.
For example, the data is decoded into a decimal number by the information decoding unit 23, and the logical operation stored in the operation storage unit 25 is sequentially read out by the information operation unit 24 in accordance with the decoded content, and the logical operation is performed. A row is created.

When each section is decoded into a decimal number in accordance with the contents by the information decoding unit 23, if the decoded value is "1" as shown in FIG.
If "2", right shift, "3", exclusive OR (XOR) of upper half and lower half of target information, "4"
If so, the logical product of the upper half and the lower half is associated with the logical operation to be executed in advance, and the correspondence is stored in the operation storage unit 25.

Next, an embodiment of the present invention will be described with reference to FIG. When signing, the control unit 12 is instructed to sign. When the control unit 12 receives the signature instruction (S1),
The signature target information is read from the signature target storage unit 13 and supplied to the modified signature target information generation unit 14, and the generation unit 14 generates, for example, 128-bit modified signature target information X in the same manner as in FIG. 3 (S2). . The modified signature target information X changes even if the original signature target information changes even by one bit.

Next, the secret information Y of the signer is read from the secret information storage unit 11 (S3), and the secret information Y and the modified signature target information X are sent to the initial information generation unit 21. The initial information generation unit 21 processes the secret information Y and the modified signature target information X to generate a plurality of mutually different initial information (S
4). That is, for example, f (X, Y) = X + Y, g (X,
Y) = X XOR Y and calculate f (X, Y)
And g (X, Y). In order to complicate this initial information generation processing, f (X, Y) and g (X, Y) may be rotated rightward in accordance with the upper 4 bits of Y. Performing the logical operation with f () and g () makes it difficult to estimate the secret information Y.

One of the generated initial information f () and g (), g (X, Y) is stored in the work information storage unit 22 (S
5) The other side f (X, Y) is supplied to the information decoding unit 23.
The information decoding unit 23 divides f (X, Y) by predetermined bits, for example, 4 bits or 8 bits, to obtain an interval sequence, decodes each interval into a decimal number, and performs an operation sequence, for example, 1,10,
Are made (S6). One operation (decimal number in this example) is sequentially fetched from the beginning of the operation sequence (S8), and a corresponding logical operation operation is respectively performed from the operation storage unit 25 by g (X,
Y) (S9), and perform each logical operation until there is no operation number in the operation sequence created by the information decoding unit 23 (S7).

A series of logical operation results for g (X, Y) obtained as described above is used as signature information, and this and the information to be signed in the storage unit 13 are transmitted through the communication processing unit 16. If the receiver who has received the information knows the signer's secret information Y and has the same storage content as the operation storage unit 25, the receiver obtains f (X, Y), g in the same manner from the received information.
(X, Y), an operation sequence is further formed from f (X, Y), and a corresponding logical operation is sequentially performed on g (X, Y), and the result matches the signature information in the received information. If so, it can be verified that the information is the signature target information signed by the true signer.

In the above description, the initial information is f (X, Y),
Although g (X, Y) is two, three or more may be used, and one of them may be used for generating an operation sequence, and the other may be subjected to a logical operation based on the decoding result. In this case, f (X, Y), g (X, Y), p (X,
In the case of generating Y), if g (X, Y) is used to generate an operation sequence, f (X, Y) XOR p (X, Y), for example, as shown in FIG. Can be performed, and complicated processing can be performed. As a more complicated logical operation sequence, three parameters p1 and p
For (2, p3), LOL is left logical shift, LOR is right logical shift, mod is modulo operation, EXOR is exclusive OR, ((p1LOR (p2mod8)) + 1) EXOR
((P3 + 1) LOL ((p2EXORp3) mod
8)) may be performed.

Further, at least one piece of initial information based on a function using X and Y as variables is created, and the information including at least one of the object X and the secret information Y is determined in advance.
One of them may be used for generating an operation sequence, and the rest may be used as a target of a logical operation operation based on the operation sequence to generate signature information.
Further, without generating the initial information, signature information may be generated by using one of the modified signature target information X and the secret information Y for generating an operation sequence and the other as a target of a logical operation operation based on the operation sequence. .

In the above description, if the same person signs the same document (information) a plurality of times, they become the same. The same signature may be different each time the signature is performed. In that case, a pseudo-random number R is generated and included in the generation of the initial information, that is, f (X, Y, R), g (X, Y,
R), and the processing after the generation of the initial information is the same as in the above-described embodiment. However, a random number R is also added to the signature information and transmitted.

As a method of using the random number R,
This may be included in the logical operation. For example, f (X, Y), g (X, Y), p (X, Y) are generated as initial information, and an operation sequence is created by one of them, g (X, Y).
(X, Y), p (X, Y) and a random number R are represented by, for example, a logical operation using decoding operation number “2” as shown in FIG. 1C.
(X, Y) × R, f (X, Y) + p (X, Y) at “3”
A logical operation including R and XR may be performed. Also in this case, the random number R is added to the signature information and transmitted. In the above description, original signature target information may be used instead of the modified signature target X.

[0018]

As described above, according to the present invention,
Using the information to be signed and the secret information (of the signer), using the information itself or the initial information obtained by mutually processing them, one is divided into sections of a predetermined number of bits, and each section is decrypted (this Not only numerical values but also logical operations may be added), the operation sequence is obtained, and the logical operations corresponding to each operation are processed for the remaining ones, so that the secret information and the modified signature target information appear directly. Instead, only the recipient who knows the secret information can verify the validity of the signature. If the logical operation operation for each decryption result stored in the operation storage unit 25 is relatively simple, the signature processing can be performed in a simple process and in a short time, and the logical operation operation can be complicated. In addition, an unauthorized signature can be reliably prevented.

In each case, f (X,
If the most significant bit of the operation result of Y) and g (X, Y) is 1, if the operation is performed in one direction, such as inverting the bits of f (X, Y) and g (X, Y), the original It's easy to make it harder to get back, and it's more fraudulently stronger.
In addition, the method of the present invention is not limited to a specific algorithm of encrypting information, but in the method of the present invention, the information itself represents a combination of various logical operation operations, thereby greatly improving the flexibility of signature, That is, the complexity can be controlled according to the importance of the signature target information.

Further, initial information or X
Alternatively, it is only necessary that the bit length of Y is divisible by the number of bits of the divided section. Once the signature device is determined, the processing to be used is not limited to 8 bits, 16 bits, or 32 bits.

[Brief description of the drawings]

FIG. 1A is a block diagram showing an example of a functional configuration of an electronic signature device capable of implementing the method of the present invention, and FIGS. 1B and 1C are diagrams showing examples of contents stored in an operation storage unit 25;

FIG. 2 is a flowchart showing a processing procedure according to the embodiment of the present invention.

FIG. 3 is a block diagram showing a functional configuration of a conventional electronic signature device.

Claims (5)

[Claims] 1. An initial information generating step of processing signature object information and secret information to generate a plurality of different initial information, and a dividing step of dividing one of the plurality of initial information into sections of a predetermined number of bits. A conversion step of converting each of the divisions into a logical operation according to the content thereof to obtain a logical operation sequence; and sequentially applying each of the converted logical operation to the rest of the plurality of initial information and signing A digital operation method for obtaining information. 2. An initial information generating step of processing at least one of the signature target information and the secret information by mutually processing the signature target information and the secret information; and determining in advance the initial information, the signature target information, and at least one of the secret information. A dividing step of selecting the determined one and dividing it into sections of a predetermined number of bits; a converting step of converting each of the sections into a logical operation according to the content thereof to obtain an operation sequence; A logical operation step of sequentially performing operation operations on the rest of the selection to obtain signature information. 3. The method according to claim 1, further comprising the step of generating a random number for generating a pseudo random number, including the pseudo random number in initial information generation of the initial information step, and adding the pseudo random number to the signature information. Or the electronic signature method according to 2. 4. A dividing step of dividing one of the signature target information and the secret information into sections of a predetermined number of bits, and a converting step of converting each of the sections into a logical operation operation according to the content to obtain an operation sequence. A logical operation step of sequentially applying each of the converted logical operation operations to the other of the signature target information and the secret information to obtain signature information. 5. The method according to claim 1, further comprising the step of: generating a pseudo-random number, including adding the pseudo-random number to the signature information during the logical operation in the conversion step, including an operation using the pseudo-random number. The digital signature method according to claim 1, 2 or 4, wherein: