KR20060074805A - Method for temporal privilege management in untrusted network storage - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method for managing time-based rights in untrusted network storage and a computer-readable recording medium having recorded thereon a program for realizing the method.

2. The technical problem to be solved by the invention

The present invention manages the authority (decryption of data) of a reader by time unit (key management) by using an asymmetric key method to solve the separation of authority between reader and writer in network storage. The purpose of the present invention is to provide a computer-readable recording medium recording a time unit authority management method and a program for realizing the method.

3. Summary of Solution to Invention

The present invention provides a method for managing rights in shareable network storage, the method comprising: providing a public key to a terminal (client) of a writer by a terminal of a storage owner; A writing step of allowing the writer's terminal to encrypt and upload data to the storage based on the public key; Providing, by the owner's terminal, to a terminal (client) of a reader, a time unit right asymmetric key that is not the same as the public key; And a reading step of causing the terminal of the reader authorized for a predetermined period based on the time unit authority to decrypt and read the encrypted data stored in the storage based on the time unit authority asymmetric key (decryption key). do.

4. Important uses of the invention

The present invention is used for the management of time unit authority in untrusted network storage.

Network Storage, Rights Management, Private Key, Public Key, Signature

Description

Method for temporal privilege management in untrusted network storage

1 is an explanatory diagram showing a key management method of Plutus according to the prior art;

2 is an exemplary explanatory diagram showing a service model of time unit authority management according to the present invention;

FIG. 3 is a diagram illustrating an embodiment of a time unit authority management method of a symmetric key based reader and writer using a hash chain according to the present invention;

4 is a flowchart illustrating an embodiment of a method for managing time unit rights of an asymmetric key based reader according to the present invention;

FIG. 5 is a detailed flowchart illustrating an initialization process in a method for managing time units of an asymmetric key based reader according to the present invention; FIG.

6 is a detailed flowchart illustrating a key distribution process in a method for managing time units of an asymmetric key based reader according to the present invention;

7 is a detailed flowchart illustrating an encryption process in a method for managing time units of an asymmetric key based reader according to the present invention;

8 is a detailed flowchart illustrating an embodiment of a decryption process in a method for managing time units of an asymmetric key based reader according to the present invention;

9 is a flowchart illustrating a method of managing time unit rights of a writer using an ID-based signature scheme according to the present invention.

The present invention relates to a method for managing time-based rights in untrusted network storage and a computer-readable recording medium having recorded thereon a program for realizing the method. In other words, untrusted network storage uses asymmetric keying to separate writers and readers, allowing anyone who has passed the access control of the storage server to write data. Time-based authority management method that enables encryption, and the authority (decryption of data) of a reader (time management), and a computer-readable recording program for realizing the method. It relates to a recording medium.

In addition, the present invention efficiently manages the authority (decryption of data) of the reader and the writer in units of time by using a symmetric key method using a hash chain in an unreliable network storage (key And a computer-readable recording medium having recorded thereon a program for realizing the method.

In addition, the present invention provides a time unit authority that can efficiently manage the authority of the writer (encryption of data) by unit of time by using an ID-based signature scheme in untrusted network storage (key management). A management method and a computer-readable recording medium having recorded thereon a program for realizing the method.

One of the biggest advantages of network storage is the sharing of data.

Therefore, because the data is not stored on my personal hardware, anyone can access my data with proper procedures if they are connected to the network. Because of this easy data sharing, network storage is becoming more and more widely available.

However, as the importance of stored data increases, the server becomes completely unreliable. In this case, encryption should ensure the safety of the data. However, in order to share data by encrypting data, decryption is required, and various problems arise in efficiency in generating, transferring, and decrypting a decryption key.

Of course, if you want to use the network storage only to store the data of the owner (Owner), there is no problem of efficiency at all, because you only need to store the encrypted key alone and update it properly, but if you share the network storage, Readers who want to read my stored data (hereinafter referred to as "readers") and writers who want to write data to my network storage (hereinafter referred to as "writers") The existence of a key management problem arises.

If a legitimate reader accesses the data through the access control of the server, only the encrypted data can be read. To decrypt the data, the reader must be directly given a decryption key from the owner. In addition, in the case of a writer, it may be necessary to directly obtain a right from the owner in order to upload meaningful data in the owner's space.

Therefore, the owner can no longer arbitrarily update the key and use it and must securely send the key to the reader (or writer) each time the key is updated.

Accordingly, the present invention basically assumes unreliable network storage, and proposes a method for efficiently and securely storing and sharing data in such an environment.

An example of how keys are managed in untrusted storage servers is "Plutus [KRSWF03]".

"Plutus" uses a key rotation scheme for efficient key management.

Basically, "Plutus" adopting the symmetric key method efficiently manages the lockbox key by using the key rotation method of the authority of the reader.

On the other hand, the authority of the writer is achieved through a signature, and basically, a signing key and a verifying key are different from each other by adopting an asymmetric key method.

The key management scheme of "Plutus" is as shown in FIG.

First, the authority management method of a reader is as follows.

이다. K₀를

초기화키(Initial key)라고 할 때, 키(Key)의 무효화(Revocation)가 일어날 때마다 다음과 같이 키 로테이션(Key rotation)을 한다.Owners of network storage use the public key (e, N) and secret key d of the Rivest-Shamir-Adleman (RSA) cryptosystem. Where N is the product of two large prime numbers, for the "Euler" function

to be. K ₀

In the case of an initialization key, each time a key revocation occurs, the key rotation is performed as follows.

According to the key rotation method as described above, if one lockbox key is known, all of the previous lockbox keys can be calculated. That is, a reader that obtains a lockbox key at any moment can read all data before revocation. However, due to the RSA assumption, lockbox keys for later data cannot be obtained. Therefore, the owner has a problem in that the updated lockbox key must be transmitted to the readers at every revocation.

Next, a description will be given of the authority management method of the writer.

In "Plutus", Writer's rights management is done by signing. There is no mention of encryption of the data that Writer uploads, only signing and Verifying. The process takes place.

As described above, the author's authority management method uses an asymmetric key method in which a signing key and a verifying key are different, and the owner whenever a revocation occurs. (Owner) updates.

The reader can obtain the updated verifying key using the data attached to the lockbox key and the file header, and as previously described in the permission management method of the reader, the previous lockbox key Because you can get a lockbox key, you can also recover your previous verifying key.

On the other hand, the signing key is generated by the owner and delivered directly to the writer. However, this method has a problem of generating and transmitting a new signing key and a verifying key to every legitimate writer for every revocation. In addition, there is a problem that a writer must have the authority of a reader for encryption. That is, there is a problem that independent authority management of the reader and the writer is impossible.

The present invention has been proposed to solve the above problems, and in order to solve the separation of the authority of the reader and the writer in network storage, the authority of the reader (a decryption of data) using an asymmetric key method. It is an object of the present invention to provide a time-based authority management method for managing a time unit (key management) and a computer-readable recording medium storing a program for realizing the method.

In addition, the present invention provides a time for efficiently managing (key management) the authority (decryption and encryption of data) of the reader and the writer by time using a symmetric key method using a hash chain in network storage. Another object is to provide a unit-rights management method and a computer-readable recording medium having recorded thereon a program for realizing the method.

In addition, the present invention provides a time-based authority management method for efficiently managing (key management) the time (encryption of data) of the writer (encryption of data) by using an ID (ID) -based signature scheme in network storage; Another object is to provide a computer readable recording medium having recorded thereon a program for realizing the method.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

According to an aspect of the present invention, there is provided a method for managing rights in sharable network storage, the method comprising: providing a public key to a terminal (client) of a writer (Owner); A writing step of allowing the writer's terminal to encrypt and upload data to the storage based on the public key; Providing, by the owner's terminal, to a terminal (client) of a reader, a time unit right asymmetric key that is not the same as the public key; And reading the encrypted terminal stored in the storage based on the time unit authority asymmetric key (decryption key) by the terminal of the reader authorized for a predetermined period based on the time unit authority. Characterized in that made.

In addition, the present invention provides a method for managing rights in shareable network storage, wherein a terminal (server) of a storage owner (Owner) selects a time-based authority root secret key (symmetric key) stored in secret by the owner. Encrypting by using a hash function and providing the terminal to a reader and a writer; And encrypting or uploading data to the storage based on the time-based authority root secret key, or allowing the writer's terminal authorized for a predetermined time period based on the time-based authority, or based on the time-based authority. And a writing / reading step of allowing the terminal of the authorized reader to restore the decryption key based on the time unit authority root secret key, and then decrypt and read the encrypted data stored in the storage.

In addition, the present invention provides a method for managing rights in a shareable network storage, in which the terminal of the storage owner is based on an ID as a terminal of a writer, independently of the authority of the reader (decryption of data). Providing a secret key of the; Allowing the writer's terminal to upload and sign data in the storage based on the secret key; And uploading valid data to the storage by verifying a signature of the terminal of the owner.

On the other hand, the present invention provides a network storage server having a processor for managing time-based rights, the function of providing a public key to a terminal (client) of the storage owner (Owner) to the terminal (client) of the writer; A writing function for encrypting and uploading data to the storage by the terminal of the writer based on the public key; Providing, by the owner's terminal, a time unit right asymmetric key not equal to the public key to a terminal (client) of a reader; And reading by the terminal of the reader authorized for a predetermined period based on the time unit authority to decrypt and read the encrypted data stored in the storage based on the time unit authority asymmetric key (decryption key). A computer readable recording medium having recorded thereon a program is provided.

In addition, the present invention provides a time-based authority root secret key (symmetric) that is stored in a network storage server having a processor by the owner of the owner (server) of the owner of the storage (Owner) for the time-based authority management; Encrypting a key) using a hash function and providing the key to a terminal of a reader and a writer; And encrypting or uploading data to the storage based on the time-based authority root secret key, or allowing the writer's terminal authorized for a predetermined time period based on the time-based authority, or based on the time-based authority. A computer for writing a program for realizing a writing / reading function to allow a terminal of the authorized reader to restore a decryption key based on the time-based authority root secret key, and then decrypt and read the encrypted data stored in the storage. It provides a recording medium that can be read by.

In addition, the present invention provides a network storage server with a processor for managing time-based authority, independently of the authority of the reader (decryption of data), and the terminal of the storage owner is a terminal of the writer. Providing a private key based on ID); A function of allowing the writer's terminal to upload and sign data in the storage based on the secret key; And a computer readable recording medium having recorded thereon a program for realizing a function of uploading valid data to the storage by the terminal of the owner verifying a signature.

The present invention relates to an efficient key management scheme in network storage with an untrusted server.

If the servers in the network storage are untrusted, data encryption is essential to ensure safety. In particular, network storage has great significance in terms of data sharing as well as simple data storage.

Accordingly, in the present invention, in order to improve the inefficiency in data sharing resulting from the encryption of data, an Asymmetric Temporal Privilege Management (ATPM) method of a reader using an asymmetric key method (ie, owner ( Owner manages the authority of writer and reader independently and efficiently through key management) and time unit authority of symmetric key reader and writer using hash chain Temporal Privilege Management (TPM) method (i.e., key management method using hash chain when writer and reader have the same authority) and writer time unit using ID-based signature method We propose a rights management scheme (ie, a key management scheme that allows a writer to encrypt and authenticate users for a period of time independently of the reader using an identity-based signature scheme). .

That is, the present invention separates the authority of the reader (decryption of data) and the authority of the writer (encryption of data) in order to improve the inefficiency caused by encryption assuming an untrusted storage server. Manage. In other words, encryption can be performed by anyone and decryption by only authorized users. Therefore, a reader authorized for a certain period of time can read all data within a specific period with one key (asymmetric key that is not the same key as a key distributed to a writer).

In addition, the present invention uses the symmetric key method to equalize the authority of the reader (decryption of data) and the authority of the writer (encryption of data and writer authentication) during the same period. At this time, in terms of computational efficiency, it manages efficiently only by calculating the hash function. Using a hash function like this enables more efficient calculation in light of the calculation of "Plutus" 's modular exponentiation.

In addition, the present invention enables an writer to encrypt and authenticate a user for a period of time independently of the reader using an ID-based signature scheme. It can be used independently or in combination with the Leader's Rights Management Method (ATPM).

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

ATPM method of reader using asymmetric key method is a method that owner of network storage independently and efficiently manages the authority of writer and reader through key management. to be.

The ATPM method separately manages the authority of the reader (decryption of data) and the authority of the writer (encryption of data) in order to improve the inefficiency caused by encryption when assuming an untrusted storage server. do. At this time, anyone can encrypt and only the authorized user can decrypt. Therefore, a reader authorized for a certain period of time can read all data within a specific period with one key (asymmetric key that is not the same key as a key distributed to a writer).

As described above, in the ATPM method, anyone can encrypt and write data by using an owner's public key, but only a specific user can read and decrypt the encrypted data. The following example focuses on the authority management of the reader.

For example, in the case of an 'Internet photo studio', anyone can upload data to a storage of an internet photo studio to develop a photo taken with his digital camera. However, since the Writer does not want anyone to open a picture stored in storage, it must be encrypted and uploaded. Users who can decrypt and read the picture should be limited to the readers of the Internet photo shop.

In addition, in the case of a 'publisher', anyone who wants to publish a book can encrypt the contents of his writing and upload it to the publisher's storage, and a specific publisher employee with a private key ( Only readers should have access to this material.

The same applies to the case of 'patent examination' or 'paper examination'. Anyone (Writer) can upload a data requesting a patent examination or a paper examination to the examination agency's storage with his or her own ideas or papers, but these uploaded materials require strict security. Must be encrypted. Users who can decrypt and open these materials should be restricted to specific readers.

On the other hand, the symmetric key-based reader and writer time unit authority management (TPM) method using the hash chain uses a hash chain when the permissions of the writer and the reader are the same. It's a way to manage effectively.

The TPM method uses the symmetric key method using a hash chain to equalize the authority of a reader (decryption of data) and the authority of a writer (encryption of data and authentication of a writer) during the same period.

On the other hand, the writer's rights management method is a key management method that enables the writer to encrypt and authenticate the user for a period of time independently of the reader by using an ID-based signature method.

For example, in the case of the newspaper homepage, nobody should write an article on the newspaper homepage. As a result, newspapers have given some writers the right to post on the newspaper's homepage, and only a small number of writers can write. Should have Of course, at this point you need to have a signature that the person with the real authority wrote. On the other hand, readers can read articles on the newspaper homepage written by authorized authors.

In addition, if the newspaper company wants to operate the homepage for a fee, only writers who have been authorized beforehand can write articles by simultaneously managing the authority of the writer group and the authority of the reader group. Can only make the article available to readers. In such a scenario, the author management of the writer group and the management of the reader group are completely independent. This can be a typical application of the author's rights management.

As shown in FIG. 2, the ATPM / TPM method is a reader in units of time (for example, year, quarter, month, week, day, etc.). Manage permissions ().

First, the Asymmetric Temporal Privilege Management (ATPM) scheme will be described with reference to FIG. 4. In FIG. 4, y / m / d means Year, Month, and Day, respectively. However, in the following process, asymmetric key based time unit authority management method will be described based on the case of daily members for convenience of explanation.

By applying existing "forward secure encryption" schemes, the owner can send one key, and the reader can store only one key to decrypt all the data for the desired period through simple calculations. .

First, the configuration process 401 will be described with reference to FIG. 5. In Figure 5, " s " is a master secret key (master secret) to randomly choose from Z / lZ . In addition, " ID " is an identity of a user.

를 생각한다(501). 단, 여기서 n은 메시지 공간의 크기이다. First of all, G is a group whose prime is l with a double linear map e .

(501). Where n is the size of the message space.

Then select any element s of Z / lZ and select any source P of G to calculate P _pub = sP (502). Then, param = (ID, G, e, P, P _pub , H ₁ , H ₂ ) is disclosed (503), and the root secret key SK _ε = sH ₁ (ID) is calculated and stored ( 504). Where ID is the identity of the owner.

Now, a key distribution process 402 will be described with reference to FIG. In this process, the owner asks the reader the asymmetric key (public key and asymmetric key, that is, the writer and asymmetry to encrypt), which is the time authority key for the corresponding time unit (year, month, day, etc.). Key).

According to the status of the annual member (y), monthly member (m), daily member (d), or the period setting (three months, six months, etc.), the appropriate key is given. However, the year, month, and day of the corresponding day are substituted into y, m, and d , respectively.

를 계산하여 (R _y, S _y )를 복호화 키로 준다. First, in the case of the soft member y, an arbitrary element r _y of Z / lZ is selected and R _y = r _y P and

Calculate and give (R _y, S _y ) as the decryption key.

을 계산하여

을 복호화 키로 준다. Further, in the case of month member (m) is, Z / of lZ any element r _y (any source of Z / lZ for annual membership hydrogen) and r _m (any source of Z / lZ on May Member hydrogen ) Then R _y = r _y P , R _m = r _m P , and

By calculating

Is given as the decryption key.

를 계산하여(603)

을 복호화 키로 준다(604). In addition, daily member (d) has, also any elements of Z / lZ, as shown in 6 r _y (open registering arbitrary circle hydrogen of Z / lZ on), r _m (Z on May Member For / lZ any element), select r _d (601) to calculate R _y = r _y P, R _m = r _m P, R _d = r _d P (602)

By calculating (603)

Is given as the decryption key (604).

Meanwhile, the encryption process 403 will be described with reference to FIG. 7. This is the process by which the owner distributes the public key to the writer so that anyone can encrypt and write data using the owner's public key.

를 선택하여(701,702) 암호문

을 생성한다(703). 단, 여기서

이다. Owners or writers are given param = (ID, G, e, P, P _pub , H ₁ , H ₂ ), corresponding year (y), month (m), day (d), and Any element of Z / lZ for message M∈ {0,1} ⁿ

Select (701,702) ciphertext

Generate 703. Where

to be.

Since this algorithm is an ID-based algorithm, anyone can encrypt the desired message and upload it to storage if they know only the system's parameters, param = (ID, G, e, P, P _pub , H ₁ , H ₂ ) .

Finally, the decryption process 404, 405 will be described with reference to FIG.

에 대해(801), 회원의 상태에 따라 가지고 있는 비밀키가 다르므로 주어진 암호문을 복호화하는 방법이 다르다. Given ciphertext

For 801, since a secret key is different according to a member's state, a method of decrypting a given cipher text is different.

을 계산하여 메시지

을 구한다. That is, in the case of the soft members (y) is, and in the key distribution process 402, using the given decryption key (R _y, S _y)

Calculate the message

Obtain

을 사용하여

을 계산하여 메시지

을 구한다. In the case of the month member m, the decryption key given in the key distribution process 402.

Using

Calculate the message

Obtain

을 사용하여(802)

를 계산하여 메시지

을 구한다(803). In addition, in the case of the daily member d, the decryption key given in the key distribution process 402, as shown in FIG.

Using (802)

Calculate the message

Obtain (803).

In the ATPM method, the time unit is limited to the annual member (y), the monthly member (m), and the daily member (d), but the time unit can be further subdivided or integrated according to the required service model. For example, it can be subdivided into annual members (y), quarter members (q), monthly members (m), main members (w), daily members (d), and the like.

That is, the ATPM method can be easily modified according to the service model. The addition of a certificate also makes it possible to apply not only ID-based but also public key-based methods. The security of this scheme is based on the security of the forward secure encryption scheme [BM99, CHK03, IR01].

First, the Temporal Privilege Management (TPM) scheme will be described with reference to FIG. 3. In FIG. 3, " S " is a root secret key stored by the owner as a secret, and " H " is a hash function.

When H is called a hash function and S is a root secret that is selected and stored by the owner, the secret key corresponding to each period is designed as follows. Distribute it to the reader and writer you have.

For example, data for the third Tuesday of May Q2 2004 is encrypted with a key of H (H (H (H (H (S, 2004), Q ₂ ), May), W ₃ ), Tue) , Members in Year 2004, Members in the second quarter of 2004, Members in the second quarter of 2004, Members in the third week of May in the second quarter of 2004, Members in the third Tuesday of May in the second quarter of 2004 It is possible to recover the decryption key from the key, so that the data can be decrypted. You can also use the above key to encrypt your data and upload it to storage. In other words, the authority of the reader and the writer is the same. This TPM method can be easily applied to any environment desired by the user, as long as the safety of the hash function is guaranteed without limitations on the group where the hash function is defined.

The ATPM method encrypts and writes data using the public key of the writer owner, whereas only a specific reader can decrypt and read the data. Emphasis was placed on managing permissions of Readers.

However, depending on the service model, authorization management to write data may be required. In this case, authority management of the writer group should be performed independently of authority management of the reader group.

Thus, a description will now be made of a time unit authority management method of a writer using an ID-based signature scheme of "Cha-Cheon".

Hereinafter referred to as "gap Diffie-Hellman group" G l has a large prime and a percentile in all the schemes Unless otherwise specified, it is assumed to be done in group G.

First, the setup process 901 will be described.

Let G = 〈P〉 as the gap DH group with prime numbers.

와

를 선택한다. 또한, 시스템 파라미터(System parameter)를 param = (G, P, P _pub , H ₁ , H ₂ )으로 공개하고 마스터 키(master key) s를 비밀로 저장한다. Calculate P _pub = sP by selecting any element s of Z / lZ and selecting the source P of G. And two hash functions

Wow

Select. It also discloses the system parameter as param = (G, P, P _pub , H ₁ , H ₂ ) and stores the master key s secretly.

Next, the extraction process (key generation process) 902 will be described.

와

을 계산하고 ID의 비밀키로서 D _ID 를 출력한다. 단, 여기서 t _s 는 권한 시작시간(starting time)이고 t _t 는 권한 종료시간(terminal time)이다. For a given ID,

Wow

Computes and prints D _ID as the ID's private key. Where t _s is the authority starting time and t _t is the terminal end time.

Next, the writing process 903 will be described.

= (M, U, h, V, t _s , t _t )를 출력한다. For a given secret key D _ID and message M , draw an arbitrary element r∈Z / lZ and sign when U = rQ _ID , h = H ₁ (M, U) , and V = (r + h) D _ID

= (M, U, h, V, t _s , t _t )

Finally, the verification process 904 will be described.

= (M, U, h, V, t _s , t _t )이 주어지면, h = H ₁ (M, U)을 계산한다. 서명이 받아들여진다는 것은

을 만족하는 것과 필요충분조건이다. Signature for message M 's ID

= Calculates given the (M, U, h, V , t s, t t), h = H 1 (M, U). Accepting a signature

Satisfies the requirements and is sufficient condition

As described above, the method of the present invention may be implemented as a program and stored in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form. Since this process can be easily implemented by those skilled in the art will not be described in more detail.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

The ATPM method according to the present invention as described above has an effect that can be directly applied to all network storages that need to separately manage the authority of a reader and a writer.

In addition, the ATPM and TPM schemes according to the present invention can improve the inefficiency of key management resulting from encryption of existing data, and have various effects depending on the desired business model.

In addition, the TPM scheme according to the present invention has an effect of overcoming the computational inefficiency that may occur from key management through the application of a hash chain.

In addition, the author's authority management method according to the present invention has an effect that can be efficiently applied to various fields that require encryption and user authentication of the writer independently of the reader.

Claims (13)

In the method of managing rights in sharable network storage, Providing a public key to a terminal (client) of a storage owner (Owner) to a terminal (client) of a writer; A writing step of allowing the writer's terminal to encrypt and upload data to the storage based on the public key; Providing, by the owner's terminal, to a terminal (client) of a reader, a time unit right asymmetric key that is not the same as the public key; And A reading step of decrypting and reading encrypted data stored in the storage based on the time-based right asymmetric key (decryption key) by the terminal of the reader authorized for a predetermined period based on the time-based right. Method of managing time-based permissions in untrusted network storage, including. The method of claim 1, The writer, And an unspecified number including the reader, and having a right (encryption of data) for encrypting and uploading data to the storage based on the public key. The method of claim 1, The reader, An authorized user having authority independent of the authority (encryption of data) of the writer, and based on the time unit authority asymmetric key (decryption key), the encrypted data stored in the storage for the predetermined period can be decrypted and read. A method for managing time-based rights in untrusted network storage, characterized in that it has the right to decrypt (decrypt data). The method according to any one of claims 1 to 3, The owner (Owner), Generating a decryption key (a kind of secret key) corresponding to the predetermined period from one public key and a root secret key, and enabling decryption of data for the predetermined period with one decryption key; How to manage hourly permissions on untrusted network storage. The method of claim 4, wherein The owner (Owner), A method of managing time-based rights in network storage, wherein a time-based right asymmetric key (decryption key) is granted according to a daily, monthly, or yearly, or set period of time. The method of claim 1, Independent of the authority (decryption of the data) of the reader, the terminal of the owner provides an ID (ID) based secret key to the terminal of the writer; Allowing the writer's terminal to upload and sign data in the storage based on the secret key; And The terminal of the owner verifying the signature and uploading valid data to the storage Method of managing time-based rights in untrusted network storage further comprising. In the method of managing rights in sharable network storage, The terminal (server) of the storage owner (Owner) encrypts the time-based authority root secret key (symmetric key) selected and stored secretly by the owner to a terminal of the reader and the writer. Providing; And Allow the writer's terminal authorized for a predetermined period based on the time unit authority to encrypt and upload data to the storage based on the time unit authority root secret key, or for a predetermined period based on the time unit authority. The writing / reading step of allowing the terminal of the authorized reader to decrypt and read the encrypted data stored in the storage after restoring the decryption key based on the time unit authority root secret key. Method of managing time-based permissions in untrusted network storage, including. The method of claim 7, wherein The owner (Owner), By granting the right of the writer (encryption of data) and the authority of the reader (decryption of data) equally, a time-based right symmetric key (encrypted according to the set period of days, months, or years, or a set period of time) / Decryption key). In the method of managing rights in sharable network storage, Independently of a reader's authority (decryption of data), a terminal of the storage owner provides an ID-based secret key to a terminal of a writer; Allowing the writer's terminal to upload and sign data in the storage based on the secret key; And The terminal of the owner verifying the signature and uploading valid data to the storage Method of managing time-based permissions in untrusted network storage, including. The method of claim 9, The ID based secret key, Method for managing time-based rights in untrusted network storage, characterized in that the writer enables encryption and user authentication for a predetermined period of time. In order to manage time-based authorization, a network storage server equipped with a processor, A function of providing a public key to a terminal (server) of a storage owner (Owner) to a terminal (client) of a writer; A writing function for encrypting and uploading data to the storage by the terminal of the writer based on the public key; Providing, by the owner's terminal, a time unit right asymmetric key not equal to the public key to a terminal (client) of a reader; And A reading function that allows the terminal of the reader authorized for a predetermined period based on the time unit authority to decrypt and read the encrypted data stored in the storage based on the time unit authority asymmetric key (decryption key). A computer-readable recording medium having recorded thereon a program for realizing this. In order to manage time-based authorization, a network storage server equipped with a processor, A terminal of a storage owner (server) encrypts a time-based authority root secret key (symmetric key) selected and stored secretly by the owner by a hash function and provides the terminal to a reader and a writer terminal. Function; And Allow the writer's terminal authorized for a predetermined period based on the time unit authority to encrypt and upload data to the storage based on the time unit authority root secret key, or for a predetermined period based on the time unit authority. Writing / reading function to allow the terminal of the authorized reader to decrypt and read the encrypted data stored in the storage after restoring the decryption key based on the time unit authority root secret key A computer-readable recording medium having recorded thereon a program for realizing this. In order to manage time-based authorization, a network storage server equipped with a processor, Independent of the authority of the reader (decryption of data), the terminal of the storage owner provides the ID-based secret key to the terminal of the writer; A function of allowing the writer's terminal to upload and sign data in the storage based on the secret key; And The owner's terminal verifies the signature and uploads valid data to the storage A computer-readable recording medium having recorded thereon a program for realizing this.

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