KR101740956B1 - Method of secure public auditing using self-certified signature in cloud storage and system of the same - Google Patents

Abstract

The present invention relates to a public audit method and system based on a self-certification signature, wherein a public audit method according to an embodiment includes issuing a private key from a TA (Trust Authority) server to a user terminal, Generating a witness based on a self-authenticating public key corresponding to the issued private key at a trust agent (TA) server and transmitting the generated witness to a third party auditor (TPA) server through the user terminal; Generating a signature for the data corresponding to the witness transmission at the user terminal, transmitting the data and the generated signature to the cloud server, and transmitting the signature to the cloud server by the third party auditor (TPA) Generates a challenge message corresponding to the transmission, and based on a response to the generated challenge message, And a step to determine whether the.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a public audit method and system based on self-certification signatures,

The present invention relates to a public audit technique based on a self-certification signature, in which a cloud service user uploads his or her data to cloud storage and transmits the data from the malicious behavior of a cloud server or other attacker through TPA (Third Party Auditor) And a technical idea for confirming whether there is modulation or not.

In the cloud environment, frequent cases of damage due to unreasonable access are frequent. To this end, security issues in the cloud environment are highlighted, and a variety of technologies are being developed.

Of these, the Self-Certified Signature Scheme is based on a self-authenticating public key. It does not need to store or verify a separate public key certificate, and instead of a certificate, . Anyone with an identifier of a particular user and a corresponding witness pair can obtain the public key and verify the signature. The self-certification signature scheme includes four steps: a setup process, a key generation process, a witness generation process, and a proof process.

First, in the setup process, the TA (Trust Authority) receives the security parameters as input values and generates the system parameters and the master secret key. In the key generation process, the user receives a security parameter as an input value to generate a public key and a private key pair. In the process of creating a witness, a TA (Trust Authority) creates a witness using a public key, which is a user's identifier, and a zero-knowledge proof of the user's private key. In addition, in the proof process, a signature for a message held by a user is generated, and a signature, a signature, a user identifier, and a witness are received as input values to verify the validity of the signature.

Korean Patent Publication No. 10-0529594 Korean Patent Publication No. 10-0561847

According to the embodiment, after a cloud service user uploads his or her data to the cloud storage, the third party auditor (TPA) checks whether data is tampered with from malicious behavior of a cloud server or other attacker.

According to the embodiment, the user's agent audits the integrity of the data uploaded to the cloud.

According to an embodiment, a new public audit protocol is provided that is secure against malicious attacks while reducing computational complexity.

A public audit method according to an exemplary embodiment of the present invention includes the steps of issuing a private key to a user terminal from a Trust Authority (TA) server, receiving a private key corresponding to the issued private key from the Trust Authority (TA) Generating a public key based witness and transmitting the generated witness to a third party auditor (TPA) server through the user terminal; generating a signature for data corresponding to the witness transmission at the user terminal; And generating a challenge message corresponding to the transmission of the signature at the third party auditor (TPA) server, and transmitting the generated challenge to the cloud server, ) Message based on a response to the message.

The step of verifying whether or not the data is modulated may include transmitting the generated challenge message to the cloud server in the third party auditor (TPA) server, Generating a response value corresponding to the challenge message in the server and transmitting the response value to the third party auditor (TPA) server, and transmitting the response value to the third party auditor (TPA) And checking whether the data is modulated based on the response value.

The step of verifying whether or not the data is modulated according to an exemplary embodiment is a step in which the third party auditor (TPA) server substitutes the response value into a predetermined verification expression to check whether or not the data is modulated do.

The step of generating the witness in the Trust Authority (TA) server according to an exemplary embodiment of the present invention includes the steps of generating a variable reflecting the generator information of the multiplication cyclic group having a prime number in the user terminal as the private key, Authenticating the user based on the generated private key and returning it to the Trust Authority (TA) server; confirming whether a validation expression is established in the authentication authority (TA) server; Verifying the zero-knowledge proof if the zero-knowledge proof is verified at the authentication authority (TA) server, generating a witness, transmitting the witness to the user terminal, and storing the witness in the database .

The step of generating the witness at the Trust Authority (TA) server according to an embodiment includes terminating the protocol if the verification expression does not hold.

The step of generating a response value corresponding to the challenge message according to an exemplary embodiment of the present invention includes performing a mode operation on all the elements constituting the challenge message, Calculating a proof value using the public key and the hash function in the result of generating the response value, and generating the response value by reflecting the calculated proof value.

The public audit method according to an embodiment of the present invention includes the steps of generating a variable reflecting a generator information of a multiplication cyclic group having a prime number in a user terminal as the private key, (TA) to the Trust Authority (TA) server; verifying that a validation expression is established in the Trust Authority (TA) server; verifying the zero-knowledge proof if the validation expression is established; When the proof-of-knowledge is verified at the TA (Trust Authority) server, a witness is generated, transmitted to the user terminal, and stored in a database.

The step of generating the witness at the Trust Authority (TA) server according to an embodiment includes terminating the protocol if the verification expression does not hold.

The public audit system according to an embodiment includes a private key issuing unit for issuing a private key from a TA (Trust Authority) server to a user terminal, a TA (Trust Authority) server for issuing a private key corresponding to the issued private key A witness generating unit for generating a witness based on a self-authentication public key, and a transmitting unit for transmitting the generated witness to a third party auditor (TPA) server through the user terminal, A third party auditor (TPA) server generates a challenge message corresponding to the transmission of the signature, and when the signature of the generated challenge is transmitted to the cloud server, ) Message based on the response to the message.

The third party auditor (TPA) server according to an embodiment transmits the generated challenge message to the cloud server, and transmits a response message corresponding to the challenge message to the cloud server Response to the third party auditor (TPA) server, and transmits the generated response to the third party auditor (TPA) server based on the response value Based authentication signature.

The third party auditor (TPA) server according to an exemplary embodiment of the present invention substitutes the response value into a predetermined verification expression to check whether or not the data is tampered with.

The third party auditor (TPA) server according to an exemplary embodiment performs a mode operation on all the elements constituting the challenge message, and performs a mode operation on all the elements constituting the challenge message. A proof value is calculated using a key and a hash function, and the response value is generated by reflecting the calculated proof value.

The public audit program according to one embodiment includes a set of instructions for issuing a private key from a TA (Trust Authority) server to a user terminal, a self-authentication (TA) certificate corresponding to the issued private key Generating a public key based witness and transmitting the generated witness to a third party auditor (TPA) server through the user terminal; generating a signature for data corresponding to the witness transmission in the user terminal; Generates a challenge message corresponding to the transmission of the signature at the third party auditor (TPA) server, and transmits the generated challenge to the third server (TPA) And a command set for confirming whether or not the data is modulated based on a response to a challenge message.

According to embodiments, after a cloud service user uploads his or her data to the cloud storage, the third party auditor (TPA) can check the tampering of the data from the malicious behavior of the cloud server or other attackers.

According to an embodiment, a user's agent can audit the integrity of data uploaded to the cloud.

According to the embodiment, a new public audit protocol can be provided that is safe against malicious attacks while reducing computational complexity.

1 is a flow diagram illustrating a public audit method based on a self-authenticating signature in accordance with one embodiment.
FIG. 2 is a flowchart illustrating an example of checking whether data is modulated based on a response value in a third party auditor (TPA) server.
3 is a flow chart illustrating an embodiment of generating a witness according to one embodiment.
4 is a flow chart illustrating an embodiment for generating a Response value.
5 is a view for explaining a public audit system according to an embodiment.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, the scope of the rights is not limited or limited by these embodiments. Like reference symbols in the drawings denote like elements.

The terms used in the following description are chosen to be generic and universal in the art to which they are related, but other terms may exist depending on the development and / or change in technology, customs, preferences of the technician, and the like. Accordingly, the terminology used in the following description should not be construed as limiting the technical thought, but should be understood in the exemplary language used to describe the embodiments.

Also, in certain cases, there may be a term chosen arbitrarily by the applicant, in which case the meaning of the detailed description in the corresponding description section. Therefore, the term used in the following description should be understood based on the meaning of the term, not the name of a simple term, and the contents throughout the specification.

1 is a flow diagram illustrating a public audit method based on a self-authenticating signature in accordance with one embodiment.

The public audit method according to an exemplary embodiment assumes a total of four parties: a user terminal of a cloud service, a trust authority (TA) server, a third party auditor (TPA) server, and a cloud server. In addition, the public audit method according to an embodiment includes a key generation process, a witness generation process, a tag generation process, a challenge message generation process of a third party auditor (TPA) server, A process of generating a response value to the challenge message, and finally, a process of confirming the validity of the response value received from the cloud server by the third party auditor (TPA) server.

Specifically, the public audit method according to an embodiment issues a private key to a user terminal (101) in a trust authority (TA) server.

와

를 랜덤하게 선택하여

와

를 계산한다. 여기서 개인키는

, 공개키는

로 설정한다.The user terminal of the cloud

Wow

At random

Wow

. Here, the private key

, The public key is

.

는 겹선형 함수이다. 인증기관(TA, Trust Authority) 서버는

를 랜덤하게 선택하고

를 계산하여

를 각각 마스터 개인키, 공개키로 설정한다. 뿐만 아니라 인증기관(TA, Trust Authority) 서버는 암호학적으로 안전한 해시(Hash) 함수

와

를 선택한다. 최종적으로 생성된 시스템 파라미터는

이다G ₁ and G ₂ are multiplicative cyclic groups with q as the power, q ₁ is the constructor of G ₁ ,

Is a folded linear function. The Trust Authority (TA) server

Randomly < / RTI >

To calculate

As a master private key and a public key, respectively. In addition, a Trust Authority (TA) server uses a cryptographically secure hash function

Wow

. The final generated system parameters are

to be

The public audit method according to an embodiment generates a witness based on a self-authentication public key corresponding to the issued private key (102) and transmits the witness to a third party auditor (TPA) server through a user terminal 103).

A public audit method according to one embodiment generates a signature for data corresponding to a witness transmission (104). In addition, the public audit method according to an embodiment transmits the data and the generated signature to the cloud server (105).

The public audit method according to an exemplary embodiment of the present invention generates (106) a challenge message corresponding to the transmission of a signature at a third party auditor (TPA) server, and transmits a response to the generated challenge message Whether or not the data is modulated is checked (107).

FIG. 2 is a flowchart illustrating an example of checking whether data is modulated based on a response value in a third party auditor (TPA) server.

In order to confirm whether data is tampered, a public audit method according to an embodiment transmits a challenge message generated in a third party auditor (TPA) server to a cloud server (201).

Next, a public audit method according to an exemplary embodiment generates a response value corresponding to a challenge message in the cloud server (202) and transmits the response value to a third party auditor (TPA) server (203).

In the public audit method according to an embodiment, the third party auditor (TPA) server checks whether the data is modulated based on a response value (204).

For example, in a public audit method, a third party auditor (TPA) server may check the data to see if the data is tampered by substituting a response value into a predetermined verification formula .

In order to verify the data integrity of the data file M of the user uploaded to the cloud, the third party auditor (TPA) server generates a challenge message for verification.

개의 샘플 블록들을 랜덤하게 선택한다. 랜덤하게 선택된 블록의 집합은 L로 표현된다. 그리고 나서

를 랜덤하게 선택한다.The third party auditor (TPA) server, instead of validating every block of the file,

Random sample blocks. The set of randomly selected blocks is represented by L. Then the

.

를 생성하여 클라우드 서버에게 전송한다.The third party auditor (TPA) server sends a challenge message

And transmits it to the cloud server.

를 받은 클라우드 서버는 이에 대한 정당한 증명 값을 계산하기 위해 다음의 절차를 수행한다. Challenge message

, The cloud server performs the following procedure to calculate a valid proof value.

에 대해

를 계산하고,

를 생성한다. 위에서 생성한 증명 값

를 제3 감사자(TPA, Third Party Auditor) 서버에 전송한다. First of all

About

Lt; / RTI >

. Proof value generated above

To a third party auditor (TPA) server.

가 검증식을 통과하는지 확인한다. The third party auditor (TPA) server uses the public parameters and UL to receive from the cloud server

Is passed through the verification equation.

와

를 계산한다.The third party auditor (TPA) server first

Wow

.

이 성립하는지 확인한다.Witness, public parameters, and verification values received from the cloud server.

.

When the verification expression is established, the integrity of the file M uploaded by the user to the cloud server can be guaranteed. Otherwise, it can be confirmed that the data has been tampered with.

3 is a flow chart illustrating an embodiment of generating a witness according to one embodiment.

A public audit method according to an embodiment generates a variable reflecting a generator information of a multiplication cyclic group with a private key to generate a witness (301).

Next, the public audit method according to an exemplary embodiment of the present invention returns zero-knowledge based on the generated private key to the Trust Authority (TA) server (302).

The public audit method according to an exemplary embodiment checks whether a validation expression is established in the TA (Trust Authority) server (303).

For example, assuming that the id _user is the user's identity, the user terminal and the TA (Trust Authority) server perform the following procedure to create the witness.

를 생성하고 이에 대한 영-지식 증명

을 계산하여 인증기관(TA, Trust Authority) 서버에

를 전송한다.The user terminal uses its own private key as a V variable,

And a zero-knowledge proof

To the Trust Authority (TA) server.

.

도 검증한다. The TA (Trust Authority) server that received the certificate verifies that the verification expression is established,

.

The public audit method according to one embodiment verifies the zero-knowledge proof when the verification equation is established (304).

In the public audit method according to an embodiment, when the zero-knowledge proof is verified at a TA (Trust Authority) server, a witness is generated, transmitted to the user terminal, and stored in the database (305).

를 생성하여

를 사용자 단말기에게 전송하며, 동시에 본인의 데이터베이스에 저장한다. 성립하지 않으면 위트니스를 생성하지 않으며 프로토콜을 종료한다. Once the validation expression is established, the Trust Authority (TA)

To generate a

To the user terminal, and at the same time stores it in the user's database. If not, the witness is not created and the protocol is terminated.

를 받으면 사용자 단말기는 정당한 위트니스인지 검증하기 위해 다음의 검증식

이 성립하는지 확인한다. 검증식이 성립한다면

는 사용자 단말기의 위트니스가 되며, 추후 무결성 검증 검사를 위해

를 제3 감사자(TPA, Third Party Auditor) 서버에 전송한다.From a Trust Authority (TA) server

The UE verifies the authenticity of the witness by using the following verification formula

. If a validation expression is established

Becomes a witness of the user terminal, and for the integrity verification test

To a third party auditor (TPA) server.

If the zero-knowledge proof is not verified at the Trust Authority (TA) server, that is, if the verification expression is not established, the public audit method ends the protocol.

4 is a flow chart illustrating an embodiment for generating a Response value.

The public audit method according to an exemplary embodiment generates a response value corresponding to a challenge message (401).

The public audit method according to an embodiment performs a mode operation (402) on all elements constituting a challenge message (402), and calculates a proof value using the public key and the hash function on the mode-calculated result (403).

The public audit method according to an embodiment generates a response value by reflecting the calculated certification value (404).

으로 구성된다. 각각의 데이터 블록

에 대한 인증 태그를 생성하기 위해 사용자는 다음과 같은 절차를 수행한다. For example, M is a data file to be uploaded to the cloud, n blocks

. Each data block

In order to generate an authentication tag for the user, the user performs the following procedure.

모든 에 대하여, 랜덤

을 선택한 후,

와

를 계산한다. 따라서 데이터 블록

에 대한 인증 태그는

이 된다.The public audit method according to one embodiment

For all, random

And then,

Wow

. Therefore,

The authentication tag for

.

를 클라우드 서버에 전송한다.The user can input the data file M to be uploaded to the cloud by himself and the corresponding authentication tag

To the cloud server.

리스트(UL)를 생성하여 제3 감사자(TPA, Third Party Auditor) 서버에게 전송한다.Of the generated authentication values,

Generates a list (UL) and transmits it to a third party auditor (TPA) server.

5 is a diagram illustrating a public audit system 500 according to an embodiment.

The public audit system 500 according to one embodiment provides a self audit signature based public audit protocol that is secure against malicious attack while ensuring the same computational efficiency.

To this end, the public audit system 500 according to an embodiment includes a private key issuing unit 510, a witness generating unit 520, and a transmitting unit 530.

The private key issuing unit 510 according to an embodiment issues a private key to a user terminal from a Trust Authority (TA) server.

The witness generating unit 520 according to an embodiment generates a witness based on a self-authenticating public key corresponding to the issued private key at an authentication authority (TA) server.

The transmitting unit 530 according to an embodiment transmits the witness generated through the user terminal to a third party auditor (TPA) server.

Thereafter, when a signature for the data generated corresponding to the witness transmission is transmitted to the cloud server, the third party auditor (TPA) server generates a challenge message corresponding to the transmission of the signature, Based on the response to the challenge message.

At this time, the third party auditor (TPA) server transmits the generated challenge message to the cloud server, generates a response value corresponding to the challenge message in the cloud server, (TPA) server, and the third party auditor (TPA) server checks whether or not the data is altered based on the response value.

The third party auditor (TPA) server replaces the response value with a predefined verification expression to check whether the data is tampered with. At this time, the third party auditor (TPA) server performs a mode operation on all the elements constituting the challenge message, and uses the public key and the hash function Calculates a proof value, and generates the response value by reflecting the calculated proof value.

The method according to an embodiment of the present invention can be implemented in the form of a program command which can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and configured for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.

Claims (13)

The Trust Authority (TA) server sends a random number (

) To select the master private key (

), Master public key (

) And system parameters (

);
When the user terminal receives an arbitrary random number (

,

) Is selected, and the arbitrary random number (

,

) ≪ / RTI > and the system parameter

) And the public key

);
The user terminal calculates the calculated value using the private key and the master public key

Proof of knowledge for

), And the calculated value (

), The public key and the zero-knowledge proof

) To the certification authority server;
Verifying that the certification authority server has established a validation formula and a zero-knowledge proof;
When the zero-knowledge proof is verified, the certification authority server sends the calculation value (

), The master private key, and the system parameters,

) And transmitting the witness to the user terminal;
Verifying the witness using the second verification equation;
(N is a natural number of 2 or more) data blocks

) And the n data blocks (

) Authentication tags (

To the cloud server;
The user terminal transmitting the witness to a third party auditor (TPA) server; And
Wherein the third auditor server receives the message (< RTI ID = 0.0 >

And generating a challenge message based on a response to the challenge message received from the cloud server,

Verifying the integrity of the < RTI ID = 0.0 >
remind

And

Quot;

As a multiplicative cyclic group,
remind

(

) Is a bilinear map,
remind

Gt;

≪ / RTI >
remind

(

) And the above

(

) Is a cryptographic hash function,
The verification equation

ego,
remind

Is an identifier of the user terminal,
The second verification equation

sign,
Public audit method.
The method according to claim 1,
The authentication tags (

) Each include a first authentication tag and a second authentication tag,
The authentication tags (

) To the cloud server comprises:
Any random number (

); And
The first authentication tag (

And the second authentication tag

≪ / RTI >
Public audit method.
The method according to claim 1,
The message (

Verifying the integrity of the < RTI ID = 0.0 >
Wherein the third party auditor (TPA) server verifies the integrity of the message by substituting the response into a predefined verification expression,
Public audit method.
delete delete The method according to claim 1,
The cloud server includes:
Performing a mode operation on all elements constituting the challenge message;
Calculating a proof value using the public key and the hash function in the performed mode computed result; And
And generating the response by reflecting the calculated authentication value to generate a response to the challenge message.
Public audit method. delete delete delete delete delete delete delete

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