KR101695361B1 - Terminology encryption method using paring calculation and secret key - Google Patents

Abstract

Disclosed is a terminology encryption method using pairing calculation and a private key. A terminology encryption method using pairing calculation and a private key according to an embodiment of the present invention comprises the steps of: setting up a system adapted to generate a bilinear pairing map, a master private key, and a public parameter; generating private keys for a transmitter and a receiver, and distributing the private keys; encrypting a broadcast message by using a set of attributes of the receiver and the public parameter so that the encrypted broadcast message can be decrypted by the receiver, and transmitting the encrypted broadcast message; and decrypting the received broadcast message by using a private key corresponding to a terminology set of the receiver.

Description

[0001] DESCRIPTION [0002] PERSONNELOGY ENCRYPTION METHOD USING PING CALCULATION AND SECRET KEY [

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a method for encrypting a predicate using a pairing operation and a secret key in a complicated network environment.

As messages are exchanged in a complex network environment, studies on terminology encryption have been actively conducted. Generally, for predicate ciphers, it specifies which attributes the ciphertext requires or which attributes can be decrypted.

Here, the attribute of the cipher text means a description of characteristics to be provided by the user who decrypts the cipher text, for example, name, affiliation, authority, and the like. Thus, even if the message can not be decrypted, since the encryption attribute is disclosed, indirect information can be known even if it is unknown what the encrypted message is.

Therefore, even if the message or information transmitted through the external network is encrypted, attributes related to the encryption / decryption (recipient name, title, affiliation, etc.) may be exposed in the process of being transmitted to the recipients of various paths in the internal network. Thus, an attacker such as a hacker can accumulate and interpret indirect information including these attributes to infer or understand a substantially encrypted message. Therefore, not only message content but also attribute information required for decoding can be safely stored.

On the other hand, since the concept of predicate encryption was introduced by Katz, Sahai, and Waters, various predicate encryption schemes have been proposed. This predicate encryption scheme encrypts one message in an attribute set and transmits it securely, but only a legitimate user can decrypt the ciphertext. At this time, users who do not have the correct predicate should collide and attack, and no plaintext information about the ciphertext should be obtained.

Many predicate encryption schemes have been proposed since then. Especially, the proposed scheme by Takashima group is a high security scheme using the concept of Dual Pairing Vector Spaces. However, Dual Pairing Vector Spaces itself is inefficient in terms of time. In particular, there is a problem that the number of public keys, secret keys, ciphertexts, encryption and decryption are linearly increased in proportion to the number of dimensions of the attribute.

Conventional predicate encryption techniques have been developed with an emphasis on enhancing the security of the proof. Accordingly, there has been a problem that an exponential operation on an elliptic curve proportional to the number of dimensions of a cryptographic attribute is required, a key must be stored, or a large amount of communication is generated. This also impacts actual application development using predicate-based cryptography.

Accordingly, it is an object of the present invention to provide a predicate encryption method which can encrypt and decrypt a message quickly and requires a low communication amount.

It is another object of the present invention to provide a method of encrypting a predicate by hiding an attribute of encryption so that a third party can not infer not only the content of the encrypted message but also the indirect information related to the message.

To this end, a predicate encryption method according to an embodiment of the present invention includes: setting up a system for generating a bilinear pairing map, generating a master secret key and a public parameter; Generating and distributing a secret key for the sender and the receiver; Encrypting and transmitting a broadcast message using a set of attributes and a public parameter of the recipient so that the receiver can decode the broadcast message; And decrypting the received broadcast message using a secret key corresponding to a set of predicates of the receiver.

를 산출한 다음, 공개 파라미터 및 마스터 비밀 키를 생성하는 단계를 더 포함하는 것을 특징으로 한다.In one embodiment, the step of setting comprises: selecting a group of asymmetric bilinear pairing maps; By selecting the generator of the subgroup of elliptic curves,

, And then generating a public parameter and a master secret key.

를 산출한 다음, 비밀 키를 생성하는 단계와; 생성된 비밀키를 송신자 및 수신자에게 전송하는 단계;를 더 포함하는 것을 특징으로 한다.In one embodiment, the distributing step comprises the steps of: distributing, by the key distribution center, the master secret key and the set of predicates of the recipient

And then generating a secret key; And transmitting the generated private key to the sender and the receiver.

In one embodiment, the step of encrypting and transmitting a message comprises the steps of generating a message encryption key using a public parameter after selecting any random number; And generating a cipher text using the public parameter and the attribute set of the receiver.

,

,

인 것을 특징으로 한다.In one embodiment,

,

,

.

를 산출하는 단계와; 수신자의 비밀키와 상기 D₀, 및 암호문을 이용하여,

를 산출하는 단계와; 상기 K^{- 1}를 이용하여 복호화된 평문

를 획득하는 단계;를 더 포함하는 것을 특징으로 한다.In one embodiment, the step of decrypting the message comprises using a set of predicates and a cipher text of the recipient

; Using the secret key of the receiver, the D ₀ , and the cipher text,

; The plaintext decrypted using the K ^{- 1}

The method comprising the steps of:

Also, a predicate encryption method according to an embodiment of the present invention includes: calculating a public parameter and a master secret key to be shared by a sender and a receiver of a message; Generating a secret key using a first random number, a public parameter, and a master secret key for a set of predicates of a receiver; Generating a message encryption key using a second random number and a public parameter for the attribute set of the receiver, and transmitting the message encryption key to a legitimate user; The sender of the message encrypts the message using the message encryption key to generate a cipher text; And if the generated ciphertext is received by the recipient, decrypting the ciphertext using the secret key to obtain a statement.

As described above, according to the predicate encryption method according to the embodiment of the present invention, since the number of times of pairing operations and keys required in the encryption and decryption processes have constant values, fast computation and low traffic volume are required. And thus can be provided for the development of a more efficient and secure communication application in a network environment composed of users and devices having various rights.

In addition, according to the predicate encryption method according to the embodiment of the present invention, since only a user or a device satisfying a set condition can be decrypted, the attribute of the cipher text is not exposed in an unprotected manner even in a network environment. As a result, an efficient and highly stable effect is provided.

1 is a flowchart illustrating a method of encrypting a predicate using a pairing operation and a secret key according to an embodiment of the present invention.
FIG. 2 is a diagram for easily understanding the detailed configuration of a predicate encryption method according to an embodiment of the present invention.

First, it is revealed beforehand that the embodiment of the present invention can be applied to all environments where encryption of a predicate is applied in a network environment or the like

In addition, the present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Terms including ordinals such as first, second, etc. described herein can be used to describe various elements, but the elements are not limited to these terms. That is, the terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. The term " and / or " includes any combination of a plurality of related listed items or any of a plurality of related listed yields.

Also, when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but other elements may be present in between have. On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

Also, the terms used in the present application are used only to describe certain embodiments and are not intended to limit the present invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, Should not be construed to preclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, or combinations thereof.

Also, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The description will be omitted.

The present invention proposes a predicate encryption method which can encrypt and decrypt a message exchanged in a network environment and requires a low communication amount. In addition, by hiding the attributes of the ciphertext, the third party can implement not only the contents of the encrypted message but also the indirect information related to the message.

The predicate encryption method according to the embodiment of the present invention largely comprises system setup, key generation and distribution, encryption, and decryption.

Referring to FIG. 1, a predicate encryption method according to an exemplary embodiment of the present invention includes a step of setting up a system (S10), a step of generating and distributing a user key (S20) (S30), and when the encrypted message is received, decrypting the received message (S40). A more detailed explanation of each step is as follows.

(1) The process of setting up the system

First, the key distribution center selects the bilinear map group system as follows.

는

를 만족하는 비대칭적 바이리니어 맵(asymmetric bilinear map)이다. Where p is a prime number, G ₁ and G ₂ are subgroups of elliptic curves, and G _T is a subgroup of extensions. And,

The

(Asymmetric bilinear map).

를 선택한다. Thus, When the selection is completed, the bilinear map (bilinear map), in the elliptic curve subgroup G ₁ constructor (generator) g, and the generator G ₂ h, and any random number

.

를 계산한다. next,

.

는 공개 파라미터이고, 마스터 비밀키는

이 된다.At this time,

Is the public parameter, and the master secret key is

.

(2) a process of generating and distributing a user key

에 대해서 임의의 난수

을 선택할 수 있다. When the system setup is complete, the key distribution center generates the master secret key and the public parameters generated above, and the user's predicate set

Lt; RTI ID = 0.0 >

Can be selected.

를 생성할 수 있다.Then, using the following equation (1), the secret key

Lt; / RTI >

The generated secret key and the set of predicates are securely transmitted to legitimate users. Here, the method for securely transmitting the generated secret key to a legitimate user, that is, a sender and a receiver of a message may be a method in which a legitimate user visits a key distribution center to present an identification card, receives a direct key, This is possible.

Hereinafter, a process of encrypting and decrypting a message will be described.

(3) The process of encrypting a message

The encryption of the message is done using the attribute set of the recipient and the public parameters.

이라고 할 경우, 송신자는 선택된 공개 파라미터를 이용해 다음과 같이 암호문을 생성할 수 있다.First, set the attribute set of the recipient to whom you want to send the message.

, The sender can generate a cipher text using the selected public parameter as follows.

을 선택한 다음, 선택된 공개 파라미터를 이용하여 이하의 수학식 2를 계산할 수 있다. 그러면, 헤더

가 생성된다.At this time,

And then calculates the following equation (2) using the selected public parameter. Then,

Is generated.

 Then, the message encryption key K can be calculated using the following equation (3).

을 생성한다. 그리고, 암호문

을 각 수신자에게 전송한다. Then, the message M to be transmitted is encrypted using the calculated K

. Then,

To each recipient.

(4) The process of decrypting the message

When the encrypted message is broadcast, decryption is performed using the secret key corresponding to the receiver's own set of predicates.

인 술어 집합

을 가지는 수신자가 전송받은 메시지를 복호화하는 과정은 다음과 같다.

In predicate set

The process of decrypting a message received by a receiver having the above-described structure is as follows.

과 암호문

을 이용하여 다음의 수학식 4를 계산할 수 있다.First, the user sets his predicate set

And ciphertext

The following equation (4) can be calculated.

와 위에서 계산한 D₀, 암호문 c₁, c₃를 이용해서 다음의 수학식 5를 계산한다.Then, the user's own private key

The following equation (5) is calculated using D ₀ calculated above and cipher texts c ₁ and c ₃ .

Then, the message can be decoded from c ₀ using the calculated K ^{- 1} , and the plaintext M 'can be extracted as follows.

On the other hand, the attribute vector and predicate vector used above can be generated as follows. Suppose here that the system is set to perform decoding only when the predicate and attribute match.

로 표현하면 되고, 술어는

로 표현하면 된다. For example, if you want to express whether two predicates v ₁ and v ₂ match for two properties x ₁ and x ₂ ,

And the predicate is

.

로 계산된다. 그리고, 가정에 따라

일 때만 0이 되어 복호화된다.At this time, if the attribute vector and the predicate vector are internalized

. And, depending on the assumption

0 " is decoded.

Hereinafter, FIG. 2 is a diagram for better understanding the detailed configuration of a predicate encryption method according to an embodiment of the present invention.

As shown, (1) in the system setup step, the cryptographic key system is disclosed and parameters are selected. Also, select the master secret key and then publish the public parameters. (2) In the key generation and distribution step, a secret key is generated for a user's predicate set and then transmitted to a legitimate user. (3) In the step of encrypting a message, first, a random number is generated by selecting an attribute set, and a session key is generated to encrypt and transmit the message. (5) The step of decrypting the encrypted message extracts the session key using the distributed secret key, and then decrypts the encrypted message using the session key. As a result, the predicate can be quickly encrypted and decrypted, and the attributes of the ciphertext are hidden.

As described above, according to the embodiments of the present invention, since the number of times of pairing operation and key required in the process of encrypting and decrypting a predicate has a constant value, a fast calculation and a low traffic amount are required do. And thus can be provided for the development of a more efficient and secure communication application in a network environment composed of users and devices having various rights. In addition, since only a user or a device satisfying a set condition can decrypt a message, the attribute of the cipher text is not exposed to unprotected even in a network environment. As a result, an efficient and highly stable effect is provided.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, And may be modified, changed, or improved in various forms. Further, the method according to the present invention described herein can be implemented in software, hardware, or a combination thereof. For example, a method according to the present invention may be stored in a software program that can be stored in a storage medium (e.g., terminal internal memory, flash memory, hard disk, etc.) and executed by a processor May be implemented with embedded codes or instructions.

Claims (7)

Establishing, by a key distribution center, a system for generating a bilinear pairing map, generating a master secret key and an open parameter;
Generating and distributing a secret key for a sender and a receiver by a key distribution center;
Encrypting and transmitting a broadcast message in a sender terminal using a property set and a public parameter of a receiver so that a receiver can decode the broadcast message; And
And decrypting the received broadcast message using a secret key corresponding to the set of predicates of the recipient at the recipient terminal,
Here, the step of setting up,
Asymmetric bilinear pairing map group,

, Wherein G ₁ , G ₂ are subgroups of elliptic curves, and G _T is a subgroup of extensions; And
In the subgroup of the elliptic curve, g, which is a generator of G ₁ , h, which is a generator of G ₂ ,

And then,

And then generating a public parameter and a master secret key,
Here,

, And the master secret key

ego,
Wherein the distributing comprises:
By the key distribution center, the master secret key, the public parameters, and the set of predicates of the recipient

A random number

And the following equation

Using the secret key

≪ / RTI > And
Generate secret key with predicate set

this

Transmitting only the secret key that satisfies the secret key to the requesting recipient,
The step of encrypting and transmitting the message comprises:
A set of attributes that represent public parameters and recipients.

And an arbitrary random number

, And using the selected public parameters,

And based on this,

,
The message encryption key K is computed using Equation

; And
The message M to be transmitted is encrypted using the encryption key K

And generates a ciphertext

To the recipient terminal,
Wherein the encryption key K and the cipher text C are generated using the same random number s to be associated with each other. delete delete delete delete The method according to claim 1,
The step of decrypting the message comprises:
The predicate set of the receiver

And ciphertext

Using

; Here,

Is a cipher text

Included in

about

And
The recipient's private key

And the calculated D ₀ and the ciphertexts C ₁ and C ₃ ,

; And
The plaintext decoded using K ^-1

The method comprising the steps of: acquiring a predicate of a predicate; Calculating, by a key distribution center, a public parameter and a master secret key to be shared by the sender and the recipient of the message;
Generating a secret key by a key distribution center using a first random number, a public parameter, and a master secret key for a set of predicates of a receiver;
Generating, by the key distribution center, a message encryption key using a second random number, a public parameter, for a set of attributes of the recipient;
Generating a ciphertext by encrypting a message using the message encryption key in a sender terminal; And
Receiving the generated ciphertext, decrypting the ciphertext using the secret key to obtain a plain text,
Here, the calculating may include:
Asymmetric bilinear pairing map group,

, Wherein G ₁ , G ₂ are subgroups of elliptic curves and G _T is a subgroup of extensions; And
In the subgroup of the elliptic curve, g, which is a generator of G ₁ , h, which is a generator of G ₂ ,

≪ / RTI >

And generating a public parameter and a master secret key,
Wherein G ₁ and G ₂ are subgroups of elliptic curves and G _T is a subgroup of extensions,

, And the master secret key

ego,
Wherein the generating the secret key comprises:
By the key distribution center, the master secret key, the public parameters, and the set of predicates of the recipient

A random number

And the following equation

Using the secret key

,
Generate secret key with predicate set

this

Transmitting only the secret key that satisfies the secret key to the requesting recipient,
Wherein the generating the message encryption key comprises:
A set of attributes that represent public parameters and recipients.

And an arbitrary random number

, And using the selected public parameters,

And based on this,

,
The message encryption key K is computed using Equation

And a step of calculating,
The step of generating the ciphertext includes:
The message M to be transmitted is encrypted using the encryption key K

And generates a ciphertext

To the recipient terminal, wherein the encryption key K and the cipher text C are generated using the same random number s to be associated with each other.

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