JPH0757017A - Electronic voting system - Google Patents

Abstract

PURPOSE:To provide the system which allows a voter to make an objection to illegal totalization open without letting other voters and a center which hold arrival vote sentences know for whom the voter votes. CONSTITUTION:This system consists of a voting device consisting of a vote sentence generating means 310 which generates a vote sentence, a signature generating means 312 which generates an undeniable signature for the vote sentence, a voting means 208 which sends the vote sentence with a blind signature to an election administration device without any name, and the election administration device consisting of a blind signature generating means 204 which gives the blind signature to the vote sentence, a signature officially announcing means 203 which makes the undeniable signature open, and a vote officially announcing means 211 which makes the received vote sentence open.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention proposes a system that minimizes the content of one's own vote that is leaked to the center when an objection is made in an electronic vote in which the voter can make an objection to fraudulent aggregation. The purpose is to

[0002]

A conventionally known electronic voting method is Ohta's method. This is disclosed in JP-A-1-177164 and 1988 IEICE Spring National Convention A-294 "Electronic Voting System Using a Single Election Administrator". In this method, a voter obtains a blind signature of an election manager for his or her own voting text and then sends this blindly to the center to realize an anonymous vote. Each voter confirms that his / her vote has been accepted and totaled in the list of voting contents announced by the center. Here, the blind signature is to obtain the signature of the center for the voting contents converted by random numbers, and then create the signature of the center for the original voting contents by removing the random number component on the voter side.

According to this Ota's method, the center's signature can be obtained only for the voting contents reflecting his own opinion.
If the center does not count the votes, it must publish its votes and challenge it.

In order to solve this problem, even when making an objection, the voter makes an objection without disclosing the content of his / her vote, so that only the tag votes that do not depend on the content of the vote are blindly signed in advance. , A method of sending a tag tag with a signature and a voting text reflecting one's opinion to the center is Japanese Patent Application No. 4-108069 and Japanese Patent Application No. 4-108069.
No. 222580 and Japanese Patent Application No. 4-292854. In these methods, the election manager publishes the list of accepted voting texts and tag votes. If your vote is not accepted, disclose the tag vote and appeal that there is a valid tag vote that was not accepted.

[0005]

[Means for Solving the Problems] Japanese Patent Application No. 4-108069
Japanese Patent Application No. 4-222580 and Japanese Patent Application No. 4-2928.
In No. 54, the center has a problem that the content of the vote of the opponent may be revealed. For example, it is assumed that the set of voting texts received by the center and the set of publicized voting texts are different due to the intention or mistake of the center. At this time, if the tag vote published by the opponent is included in the set of received voting texts, the center may find that the voting text sent with the tag vote is the content of the vote of the opponent. Recognize.

According to the present invention, even if the difference between the set of voted texts received by the center and the set of accepted voted texts is known, a method of not leaking information for specifying the content of the vote of the objector by the objection is disclosed. suggest.

[0007]

According to a first aspect of the invention, there is provided an electronic voting system in which an electronic voting system uses a cipher to vote between a plurality of voting devices and an election management device. And a voting means for transmitting a blind signature-attached voting text anonymously, wherein the election management device is configured to convert the voting text into a voting text. Blind signature generating means for performing the blind prominence,
It is characterized by comprising a signature publication means for publishing an undeniable signature and a vote publication means for publishing all accepted voting texts.

An electronic voting system according to a second aspect of the invention is characterized in that, in the first aspect of the invention, the vote disclosure means publishes a vote text encrypted with a public key that has been disclosed in advance.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the first and second inventions will be described with reference to FIGS.

As shown in FIG. 2, the electronic voting system of the present invention is used for m voter subsystems 101 (1) to 101.
(M) and one election management center 100 are connected to each other by a secure communication channel (for example, a data line) 105, which can be used in a registered form or in an anonymous form, and is a bulletin board that only the election management center 100 can write. , Bulletin board 102 readable by all voter subsystems
An example of implementation in the anonymous electronic voting system in the case where there exists is described. For the sake of simplicity, the election management center will be called the center, and the voter subsystem will be called the voter.

This voting system comprises a preparation phase, a signature generation phase, a voting phase and a result publication phase.

The first invention relates to a signature generation phase, and the second invention relates to a result publication phase.

First, the preparation phase of the first invention will be described with reference to FIG.

As a preparation for implementing this anonymous electronic voting system, the center 100 sets a constant for signature,
The constant is posted on the electronic bulletin board 102. For example, RSA encryption is used as a blind signature method, and Fujioka, who was announced at the Information Security Symposium in 1992 as an undeniable well-known (hereinafter abbreviated as U signature) method.
The Okamoto-Ota method is used. Therefore, let n _{C be} the product of two prime numbers p _c and q _c , and let e _c and d _c be e _c · d _c = 1
It is an integer that satisfies mod (p _c -1) (q _c -1).
Next, let p be a prime number and g be g ⁱ modp (i = 1,
2 ,. ． ． Let p-1) be constants that all have different values. At this time, the center sets e _c , n _c , p, and g as constants. (Step 11). These constants are written on the electronic bulletin board 102 (step 12). This constant e in the future
_{Since c} , n _c , p, and g are frequently used, the constant holding means 201 can be easily written and accessed (step 13). On the other hand, d _c is stored in its own secret information holding means 202 (step 14).

Next, the center 100 defines rules regarding voting. First, clarify the agenda for voting. Next, the following voting formats are possible, for example. Connected opinion x and random number y

[0016]

And its hash value

[0018]

Concatenation of

[0020]

Let be a voting sentence v. At this time, v is smaller than n _c as a value. The opinion x may be a choice number given in advance, or may be a text in free form replaced with an ASCII character string (step 15).

Next, the names of subsystems (hereinafter referred to as voters) who have the right to vote are listed (step 16). The deadline for the signature generation and voting phase is set and announced (step 17), and the start of the signature generation phase is signaled (step 18).

The above is the preparation phase.

Next, the signature generation phase and the voting phase will be described. In both phases, the election management center 100
Takes the same procedure for each voter, so the description will be continued by taking the procedure for a specific voter or subsystem 101 (i) as an example.

As shown in FIG. 1, in the anonymous electronic voting system, the center 100 writes a fixed number and voting rules on the electronic bulletin board 102, a secure communication channel 103, and a voter 101.
(I) is composed of a secure communication channel 104 (i) for reading the contents written on the electronic bulletin board 102 and a secure communication channel 105 (i) for communicating with the voter and the sensor.

First, referring to FIG. 1, the voter 101
The signature creation phase of (i) will be described.

The voter 101 (i) uses the bulletin board reading means 301 to read the contents written on the bulletin board 102 and stores the constants e _c , n _c , p and g in the constant holding means 302 while reading them. A voting sentence v conforming to the format is created by the voting sentence creator 310. That is,
According to the voting format, the voting v reflecting the voting content x of the user is generated as follows.

[0028]

Here, the random component y is the output of the generator 303.

Next, the voting sentence converter 304 uses the output r of the random number generator 303 and the constants e _c and n _c ,

[0031]

Then, the converted voting text s is output. Further, the output r of the random number generator 303 at this time is stored in the random number holder 309.

Next, to generate a signature u corresponding to v in U signature generation unit 312 as described below, using the output k of the generator 303, a u ₁ = g ^k modp as u _1, as u ₂ , U ₂ = v ^k modp is generated, and u = (u ₁ , u ₂ ).

The signed communication means 305 transmits s and u to the center 100 through the safety channel 105 (i).

The center 100 receives the converted voting text s and the U signature u from the legitimate voters received by the U signature receiving means 206.

The blind signature generator 204 uses d _c and n _c read from the secret holding means 201 and the constant holding means 202,

[0037]

Calculate and output The blind signature transmitting means 205 transmits D to the voter 101 (i).

The center 100 also receives the received U signature u together with the name of the voter 101 (i) and the U signature publishing means 203.
The center declares that it will shift to the voting phase if it sends blind signatures to all voters who have created the U-signature announced in. The above is the signature generation phase.

Next, the voting phase will be described.

The signature converting means 306 uses D received from the center 100 by the blind signature receiving means 311 and e _c and n _c read from the constant holding means 302.

[0042]

It is verified whether or not is satisfied. If confirmed, T = D / rmodn _c is calculated using the integer r read from the random number holder 309 and n _c read from the constant holding unit 302.

The T is the public key e _c , n _{c of the} center.
Is a signature sentence of the voting sentence v that can be verified by. That is,

[0045]

Is snarling. Obtaining the signature of the converted voting text and obtaining the signature of v without showing the voting text v itself to the center is called a blind signature, and a series of voting text converter 304, blind signature generator 204, and signature conversion means. 306 is a voting text authentication means.

The anonymous transmission means 308 sends the voting text T with the signature of the center obtained by the voting text authentication means to the center 100 without adding the sender name.

The center 100 uses the received T

[0049]

Calculate α is equal to v if the voter is not cheating. If α is a predetermined tag format, x is extracted from this and tabulated.

When everyone has voted, the center publishes the results. That is, a list of all voting texts is posted on the bulletin board. Each voter can view the list to see if their votes have been aggregated. If not, you can point out that your vote is overdue by the method of objection described below, and at this time other voters will know what you voted for There is no such thing.

The method of objection will be described. Suppose voter 101 (i) challenges. At this time, the center 100 uses the U signature u = (u ₁ , of the voter 101 (i),
Since u ₂ ) has been received by the U signature receiving means 206 in advance, the following protocol is performed based on this. Hereinafter, the voter 101 (i) is referred to as the claimant.

The claimant indicates that none of the published acceptance ballots correspond to his U-signature. Therefore, the set of published acceptance voting sentences is set as v _j (j = 1, 2, ...), and the following is performed for each v _j .

The sovereign authority generates a random number a from a random number generator,

[0055]

Create and send to the center.

The center arbitrarily selects 0 or 1 as h,
Reply h to the sovereign.

The sovereign person replies with f = a + h · k.

The center is

[0060]

Check whether or not When h is 0 both are true, when h is 1

[0062]

Only one should hold. The above protocol is repeated a predetermined number of times (for example, 20 times) using different a and h for each v _j .

If all v _j can be confirmed as expected, the center considers the opponent's assertion to be correct. That is, the center acknowledges that the opponent's voting text has been disclosed and leaked.

Regarding the correctness of this protocol, refer to the document "Interactive Bi-proof and Undeniable Signature Method".
(Fujioka, Okamoto, Ota, 1991 Symposium on Cryptography and Information Security 2B).

By doing as described above, it is possible to prove that the vote of the opponent is not counted, while hiding what the opponent has voted for other voters. In addition, even the Center, which may have a collection of ballots that have not been aggregated, does not know which of the voter's ballots are.

Next, an embodiment of the second invention will be described with reference to FIG.

In the preparation phase, the embodiment of the first invention is carried out in the same manner as in the preparation phase, but in step 11, the center further generates RSA encryption keys n ₂ , e ₂ , d ₂ and in step 12, the public key. In addition to posting e ₂ and n ₂ , in step 13, a place where d ₂ is written in its own constant holding means 201 is added.

Also, the U signature generation phase is performed in the same manner as in the first embodiment of the invention, but the reading and storing of e ₂ and n ₂ are added in the bulletin board reading means 313.

The voting phase is performed in the same manner as in the first embodiment of the invention, but the voting text encryption means 307 which receives the output V of the name conversion means 306 in the voting phase is provided. In this voting text encryption means, the voting text V is encrypted as follows. Using n ₂ and e ₂ read from the constant holding means 302,

[0071]

By calculating, the anonymous transmission means 408 sends V ′ to the center 100 without adding the sender name.

The center 100 uses the received V'in the acceptance slip verification means 417.

[0074]

Calculate α is equal to v if the voter is not cheating. If α is a predetermined voting text format, verify this and whether the voting text has been used previously. If it is not used, x is extracted from this and this is totaled.

As the publicizing means, V'that remains encrypted is used.
You can check whether or not each person's voting text is totaled by posting. Further, when an objectionist is issued, the encryption of all voting texts may be decrypted and the objection protocol may be executed as in the first embodiment.

In the above second embodiment, the voter sends the encrypted voting text in advance, but the voter sends it without encryption as in the first embodiment, and the center 100 sends it. Each voted text may be encrypted and disclosed together with the public keys e ₂ and n ₂ . At this time, each voter may confirm whether or not the vote texts sent by himself / herself are encrypted by e ₂ and n ₂ and are properly counted.

Referring to FIG. 4, the system described in any of the embodiments has a terminal unit (TMU) 401 such as a personal computer having a communication processing function, a read-only storage unit (ROM) 402, and a random access storage. Device (RAM) 403, (RNG) 404, signal processor (SP) 406, TMU 401, ROM 40
2, a RAM 403, an RNG 404, and a common bus 405 interconnecting the SP 406.

The RNG 404 generates a random number according to a command from the SP 406. This is used when the center 100 sets a constant, and the random number generator of each voter 101 (i) uses 303
Used as. In the case of the center 100 in the ROM 407,
It becomes the constant holding means 202 or the secret information holding means 201. The secret information may be stored in the RAM from the TMU as needed. In the case of the voter subsystem 101 (i), the ROM 407 includes a constant holding unit 302, a random number holder 309, and the like. The above operation is realized based on the program stored in the ROM. RAM403
Is used to temporarily store the intermediate calculation results during the execution of these steps.
01 (i) is a data processing device such as a general-purpose electronic calculator or an IC
It may be a card.

[0080]

As described above in detail, according to the present invention, a voter can open an objection to an illegal count without letting other voters know what he / she voted for. In addition, it is possible to realize an electronic voting system that minimizes the amount of information leaked to the center about the contents of its vote. In this electronic voting system, it is not necessary to set options in advance, and it can be easily applied to a free-filled questionnaire.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an electronic voting system of the first invention.

FIG. 2 is a diagram showing an anonymous electronic voting system.

FIG. 3 is a diagram showing an example of a preparation phase.

FIG. 4 is an example of a system used in an embodiment of the present invention (a diagram showing the configurations of a center 100 and a voter subsystem 101 (i)).

FIG. 5 is a block diagram showing an embodiment of an electronic voting system of the second invention.

[Explanation of symbols]

 100 Election Management Center 101 (i) Voter Subsystem 102 Electronic Bulletin Board

Claims (2)

[Claims] 1. An electronic voting system for voting between a plurality of voting devices and an election management device using encryption, wherein the voting device is a voting sentence generating means for creating a voting sentence, and an answer to the voting sentence. A signature generating means for generating a niable signature, and a voting means for transmitting a blind signature-voted text with a blind name, the election management device, a blind name generation means for performing the blind signature on the voting text, and An electronic voting system comprising: a public name publicizing means for publicizing the undeniable prominent name; and a vote publicizing means for publicizing all accepted voting sentences. 2. The electronic voting system according to claim 1, wherein the vote publishing means publishes a voting text encrypted with a public key that has been published in advance.