WO2021025185A1

WO2021025185A1 - Apparatus and method for encoding whitebox cryptography by using anti-inversion function

Info

Publication number: WO2021025185A1
Application number: PCT/KR2019/009701
Authority: WO
Inventors: 염용진; 김예원; 박호중; 강주성
Original assignee: 국민대학교산학협력단
Priority date: 2019-08-02
Filing date: 2019-08-05
Publication date: 2021-02-11
Also published as: KR102319699B1; KR20210015403A

Abstract

The present invention relates to an apparatus and a method for encoding whitebox cryptography by using an anti-inversion function, the cryptography encoding apparatus comprising: a plain text reception unit for receiving an encoded plain text; a cryptography calculation unit for generating, as an output, a cryptogram encoded through a whitebox cryptography process using the encoded plain text as an input; and an anti-inversion function application unit for dividing the encoded cryptogram into a plurality of cryptography blocks, and generating a final cryptogram by applying the anti-inversion function to any one of the plurality of cryptography blocks. Therefore, the present invention can safely protect a cryptographic key from various attacks when performing a cryptographic function by using software in a PC or mobile environment.

Description

White box encryption encoding device and method using anti-inversion function

The present invention relates to a white box encryption technology, and more particularly, a white box encryption using an anti-inversion function that can securely protect an encryption key from various attacks when performing an encryption function with software in a PC or mobile environment. It relates to an encoding apparatus and method.

Whitebox cryptography (WBC), which started in 2002, is a technology that provides secure cryptographic functions while protecting cryptographic keys from various attackers. It is assumed that an attacker with a whitebox password can take over all the resources of the system with techniques such as memory dumping and algorithm reversing.

In general, a technique of hiding encryption keys while implementing standard ciphers (AES, DES, etc.) in a table manner is mainly used. However, all white box encryption technologies for which design methods have been disclosed so far have a vulnerability such as exposure of encryption keys. In the case of a password developed exclusively for white box, a lot of memory is required to secure sufficient security (128-bit level), and it is difficult to prove objective safety.

Recently, the development of mobile finance-related apps (APP) is active, and the demand to perform credit card payments with only software is increasing, so interest in white box encryption technology necessary for the execution of secure passwords is increasing rapidly.

[Prior technical literature]

[Patent Literature]

Korean Patent Publication No. 10-2010-0122107 (2010.11.19)

An embodiment of the present invention is to provide an apparatus and method for encoding a white box password using an anti-inversion function capable of safely protecting an encryption key from various attacks when performing an encryption function using software in a PC or mobile environment.

An embodiment of the present invention is to provide an apparatus and method for encoding a white box password using an anti-inversion function applicable to copyright protection technologies such as preventing illegal copying by providing only an encryption or decryption function to a user.

An embodiment of the present invention is to provide an apparatus and method for encoding a white box password using an anti-inversion function that enhances the security of external encoding so that a white box attacker cannot perform an attack that obtains a decryption function from the encryption function.

Among embodiments, the apparatus for encoding a white box encryption using an anti-inversion function includes a plaintext receiving unit that receives the encoded plaintext, and encryption that generates the encrypted ciphertext as an output through a whitebox encryption process that receives the encoded plaintext. The calculation unit and the encoded cipher text are divided into a plurality of cipher blocks, and an anti-inversion function is applied to any one of the plurality of cipher blocks to generate a final cipher text, and the anti-inversion The function is an anti-inversion function that generates an output block from an input block and provides one-wayness to the white box encryption process by implementing the input block to be recoverable when a secret key is applied to the output block. It includes a function application unit.

The encryption operation unit may apply an iterative operation on a plurality of round functions implemented as a look-up table as the white box encryption process.

The encryption operation unit may apply a nonlinear encoding function as an internal encoding in steps before and after each of the plurality of round functions.

The encryption operation unit may apply an external encoding function different from the internal encoding to an output of the last round function among the plurality of round functions.

The anti-inversion function application unit may generate the final cipher text by connecting the output block of the anti-inversion function with the rest of the plurality of cipher blocks.

Among embodiments, the apparatus for encoding a white box cipher using an anti-inversion function further includes a ciphertext decoding unit for recovering the original ciphertext related to the encoded ciphertext by applying a decoding function to the final ciphertext.

The ciphertext decoding unit may recover the first cipher block by applying the inverse function of the anti-inversion function to the output block of the anti-inversion function among the final ciphertext based on the secret key.

The ciphertext decoding unit may recover the original ciphertext by applying an inverse function of an external encoding function to the entire cipher block including the first cipher text and the remaining cipher blocks of the final cipher text.

Among the embodiments, the method of encoding a white box cipher using an anti-inversion function includes receiving an encoded plaintext, generating an encoded ciphertext as an output through a whitebox encryption process taking the encoded plaintext as input, and Dividing the encoded ciphertext into a plurality of cipher blocks and applying an anti-inversion function to any one of the plurality of cipher blocks to generate a final ciphertext, the anti-inversion function And when generating an output block from an input block and applying a secret key to the output block, the input block is implemented to be recoverable, thereby providing one-wayness to the white box encryption process.

The disclosed technology can have the following effects. However, since it does not mean that a specific embodiment should include all of the following effects or only the following effects, it should not be understood that the scope of the rights of the disclosed technology is limited thereby.

The apparatus and method for encoding a white box encryption using an anti-inversion function according to an embodiment of the present invention may be applicable to copyright protection technology such as preventing illegal copying by providing only an encryption or decryption function to a user.

The apparatus and method for encoding a white box password using an anti-inversion function according to an embodiment of the present invention can enhance the safety of external encoding so that a white box attacker cannot perform an attack that obtains a decryption function from an encryption function.

1 is a diagram illustrating a white box encryption encoding system according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a physical configuration of the encryption encoding apparatus in FIG. 1.

3 is a block diagram illustrating a functional configuration of the encryption encoding apparatus in FIG. 1.

4 is a flowchart illustrating a process of encoding and decoding a white box cipher using an anti-inversion function performed in the cipher encoding apparatus of FIG. 1.

5 is an exemplary diagram illustrating a general white box encryption process.

6 is an exemplary diagram illustrating an anti-inversion function.

7 is an exemplary diagram illustrating a white box encryption process to which anti-inversion encoding is applied.

8 is an exemplary diagram illustrating an anti-inversion decoding process.

Since the description of the present invention is merely an embodiment for structural or functional description, the scope of the present invention should not be construed as being limited by the embodiments described in the text. That is, since the embodiments can be variously changed and have various forms, the scope of the present invention should be understood to include equivalents capable of realizing the technical idea. In addition, since the object or effect presented in the present invention does not mean that a specific embodiment should include all of them or only those effects, the scope of the present invention should not be understood as being limited thereto.

Meanwhile, the meaning of terms described in the present application should be understood as follows.

Terms such as "first" and "second" are used to distinguish one component from other components, and the scope of rights is not limited by these terms. For example, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component.

When a component is referred to as being "connected" to another component, it should be understood that although it may be directly connected to the other component, another component may exist in the middle. On the other hand, when it is mentioned that a certain component is "directly connected" to another component, it should be understood that no other component exists in the middle. On the other hand, other expressions describing the relationship between the constituent elements, that is, "between" and "just between" or "neighboring to" and "directly neighboring to" should be interpreted as well.

Singular expressions are to be understood as including plural expressions unless the context clearly indicates otherwise, and terms such as “comprise” or “have” refer to implemented features, numbers, steps, actions, components, parts, or It is to be understood that it is intended to designate that a combination exists and does not preclude the presence or addition of one or more other features or numbers, steps, actions, components, parts, or combinations thereof.

In each step, the identification code (for example, a, b, c, etc.) is used for convenience of explanation, and the identification code does not describe the order of each step, and each step has a specific sequence clearly in context. Unless otherwise stated, it may occur differently from the stated order. That is, each of the steps may occur in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order.

The present invention can be embodied as computer-readable codes on a computer-readable recording medium, and the computer-readable recording medium includes all types of recording devices storing data that can be read by a computer system. . Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, and optical data storage devices. Further, the computer-readable recording medium is distributed over a computer system connected by a network, so that the computer-readable code can be stored and executed in a distributed manner.

All terms used herein have the same meaning as commonly understood by one of ordinary skill in the field to which the present invention belongs, unless otherwise defined. Terms defined in commonly used dictionaries should be construed as having meanings in the context of related technologies, and cannot be construed as having an ideal or excessive formal meaning unless explicitly defined in the present application.

Referring to FIG. 1, the white box password encoding system 100 may include a user terminal 110, a password encoding device 130, and a database 150.

The user terminal 110 may correspond to a computing device that provides a plain text to the cryptographic encoding device 130 and receives an encrypted text for the plain text, and may be implemented as a smartphone, a laptop computer, or a computer, but is not limited thereto, It can be implemented in various devices such as a tablet PC. The user terminal 110 may be connected to the encryption encoding apparatus 130 through a network, and a plurality of user terminals 110 may be connected to the encryption encoding apparatus 130 at the same time.

The encryption encoding apparatus 130 may be implemented as a computer or a server corresponding to a program that receives the plain text and generates the encrypted text through a white box encryption process to which an anti-inversion function is applied. The white box cipher can be a technology that hides the encryption key used for data encryption, and can be a secure implementation method even in a strong attacker environment such as memory dump or reversing. The encryption encoding device 130 may be wirelessly connected to the user terminal 110 through Bluetooth, WiFi, a communication network, and the like, and may exchange data with the user terminal 110 through a network.

In one embodiment, the encryption encoding apparatus 130 may store information necessary in the process of encrypting plain text by interworking with the database 150. Meanwhile, unlike FIG. 1, the encryption encoding apparatus 130 may be implemented by including the database 150 inside, and may be implemented in a form that is included in the user terminal 110 and operates. In addition, the encryption encoding apparatus 130 may be implemented including a processor, a memory, a user input/output unit, and a network input/output unit, which will be described in more detail with reference to FIG. 2.

The database 150 may correspond to a storage device that stores various pieces of information necessary in a white box encryption process using an anti-inversion function. The database 150 may store information on plain texts collected from a plurality of user terminals 110, and may store information on a lookup table used for white box operation, but is not necessarily limited thereto, and an encryption encoding device In the process of encoding the white box encryption using the anti-inversion function 130, information collected or processed in various forms may be stored.

Referring to FIG. 2, the encryption encoding apparatus 130 may include a processor 210, a memory 230, a user input/output unit 250, and a network input/output unit 270.

The processor 210 may execute a procedure for receiving the plain text and processing each operation in the process of generating the cipher text through a white box encryption process using an anti-inversion function, and a memory that is read or written throughout the process. 230 may be managed, and a synchronization time between the volatile memory and the nonvolatile memory in the memory 230 may be scheduled. The processor 210 may control the overall operation of the encryption encoding device 130, and is electrically connected to the memory 230, the user input/output unit 250, and the network input/output unit 270 to control data flow between them. I can. The processor 210 may be implemented as a CPU (Central Processing Unit) of the encryption encoding device 130.

The memory 230 is implemented as a nonvolatile memory such as a solid state drive (SSD) or a hard disk drive (HDD), and may include an auxiliary storage device used to store all data required for the encryption encoding device 130, A main memory device implemented with volatile memory such as random access memory (RAM) may be included.

The user input/output unit 250 may include an environment for receiving a user input and an environment for outputting specific information to a user. For example, the user input/output unit 250 may include an input device including an adapter such as a touch pad, a touch screen, an on-screen keyboard, or a pointing device, and an output device including an adapter such as a monitor or a touch screen. In one embodiment, the user input/output unit 250 may correspond to a computing device connected through a remote connection, and in such a case, the encryption encoding device 130 may be performed as a server.

The network input/output unit 270 includes an environment for connecting to an external device or system through a network, and includes, for example, a local area network (LAN), a metropolitan area network (MAN), a wide area network (WAN), and a VAN ( Value Added Network) may include an adapter for communication.

Referring to FIG. 3, the encryption encoding apparatus 130 includes a plaintext receiving unit 310, an encryption calculating unit 330, an anti-inversion function applying unit 350, a ciphertext decoding unit 370, and a control unit 390. I can.

The plaintext receiver 310 may receive the encoded plaintext. That is, the plaintext receiving unit 310 may receive an externally encoded plaintext and provide it as an input for a white box encryption process. Here, the encoded plaintext may be obtained as a result of performing external encoding using data as an encryption target as plaintext, and may be generated by an external device through an external encoding function.

In an embodiment, the plaintext receiving unit 310 may receive the encoded plaintext and divide it into a plurality of plaintext blocks. Each of the plurality of plaintext blocks may be used as an input in the whitebox encryption process, and encryption operations for each plaintext block may be performed in parallel according to the operation mode of the whitebox encryption.

The encryption operation unit 330 may generate an encoded ciphertext as an output through a white box encryption process in which the encoded plaintext is input. The white box encryption process, for example, in the implementation of a general block encryption algorithm, implements the algorithm as a look-up table and hides the encryption key in it so that external attackers cannot easily infer the encryption key. May correspond to technique. In particular, in the white box encryption process, in order to prevent the size of the lookup table from becoming too large, the lookup table is properly separated by an encryption technique, but encoding and decoding can be performed so that the intermediate value of the encryption operation is not exposed. And, this will be described in more detail in FIG. 5.

In an embodiment, the encryption operation unit 330 may apply an iterative operation on a plurality of round functions implemented as a look-up table as a white box encryption process. The encryption operation unit 330 may implement each round function as a table reference to implement a white box, and may perform an encryption operation in which a plurality of round functions are continuously repeated. The round function may differ according to the cryptographic algorithm and may be formed of a combination of SubBytes, ShiftRows, MixColumns, and AddRoundKey functions.

In an embodiment, the encryption operation unit 330 may apply a nonlinear encoding function as an internal encoding in steps before and after each of the plurality of round functions. The encryption operation unit 330 may continuously perform encoding and decoding between round functions in order to prevent exposure of the intermediate value, and specifically, output of the previous round function in the previous step of each round function. After decoding is used as an input, the result of the round function is encoded in a later step of each round function, and then output can be provided to the next round function.

In an embodiment, the encryption operation unit 330 may apply an external encoding function different from the internal encoding to an output of the last round function among the plurality of round functions. The white box encryption process performed by the encryption operation unit 330 may consist of a plurality of round functions, and an internal encoding may be applied between each round function.

However, the first round function may be applied to the external encoding function used for encoding in order to decode the encoded plain text received by the plain text receiving unit 310, and the last round function terminates the white box encryption process and provides output. For this purpose, an external encoding function different from the internal encoding can be applied. In this case, the external encoding applied to the first round function and the external encoding applied to the last round function may be different from each other, and may be preset by the encryption encoding device 130.

The anti-inversion function application unit 350 divides the encoded cipher text into a plurality of cipher blocks and generates a final cipher text by applying an anti-inversion function to any one of the plurality of cipher blocks. can do. Here, the Anti-Inversion function is implemented to recover the input block only when an output block is generated from the input block and a secret key is applied to the output block, so that the white box encryption process is one-way. wayness) can be provided. The anti-inversion function will be described in more detail in FIG. 6.

In an embodiment, the anti-inversion function application unit 350 may generate a final cipher text by connecting the output block of the anti-inversion function with the rest of the plurality of cipher blocks. That is, the anti-inversion function application unit 350 receives the encrypted ciphertext from the encryption operation unit 330 as a result of the plurality of round functions, divides it into a plurality of cipher blocks, and divides the cipher text into a plurality of cipher blocks. The anti-inversion function can be applied only to the cipher block, and the remaining cipher blocks to which the anti-inversion function is not applied among the plurality of cipher blocks can be used as it is in the final cipher text without any separate processing.

The ciphertext decoding unit 370 may apply a decoding function to the final ciphertext to recover the original ciphertext for the encoded ciphertext. The original ciphertext may correspond to the ciphertext generated in the original encryption process, and the external encoding and the internal encoding applied in the encryption process may be obtained as a result of removing by each decoding. In another embodiment, the ciphertext decoding unit 370 may be independently implemented outside of the ciphertext encoding device 130, in this case, the ciphertext decoding unit 370 may store a preset secret key, and the encryption encoding device ( 130), a decoding operation may be performed after receiving the final encrypted text.

In an embodiment, the ciphertext decoding unit 370 may recover the first cipher block by applying an inverse function of the anti-inversion function to the output block of the anti-inversion function among the final ciphertext based on the secret key. That is, the first cipher block may correspond to a cipher block to which the anti-inversion function has been applied by the anti-inversion function application unit 350. The inverse function of the anti-inversion function may perform an operation of recovering an input block based on an output block, and a secret key may correspond to a prerequisite for the operation.

In one embodiment, the ciphertext decoding unit 370 may recover the original ciphertext by applying an inverse function of the external encoding function to the entire cipher block including the first cipher block and the remaining cipher block of the final ciphertext. As a result, after the first encryption block is recovered, the recovery process for the original ciphertext may correspond to a process of removing the external encoding by applying decoding to the externally encoded ciphertext.

The control unit 390 controls the overall operation of the cryptographic encoding device 130, and a control flow between the plain text receiving unit 310, the cryptographic operation unit 330, the anti-inversion function application unit 350, and the cryptogram decoding unit 370 Or you can manage the data flow.

Referring to FIG. 4, the encryption encoding apparatus 130 may receive an encoded plaintext through the plaintext receiving unit 310 (step S410). The encryption encoding apparatus 130 may generate the encoded ciphertext as an output through a white box encryption process in which the plaintext encoded through the encryption operation unit 330 is input (step S430).

In addition, the encryption encoding device 130 divides the encrypted text encoded through the anti-inversion function application unit 350 into a plurality of encryption blocks and applies an anti-inversion function to any one of the plurality of encryption blocks. Thus, a final ciphertext can be generated (step S450). The cipher encoding apparatus 130 may apply a decoding function to the final ciphertext through the ciphertext decoding unit 370 to recover the original ciphertext related to the encoded ciphertext (step S470).

5 is an exemplary diagram illustrating a general white box encryption process.

5, the white box encryption process (S530) is a process of generating an encoded ciphertext by inputting an encoded plaintext in the entire encryption process (S500) of generating a ciphertext 530 based on the plaintext 510 May correspond to. The plaintext encoding process (S510) applying external encoding to the plaintext and the ciphertext encoding process (S550) applying external encoding to the encoded ciphertext may be performed independently from the whitebox encryption process (S530), and each process Can be performed in an independent device or system.

In particular, the white box encryption process S530 may be implemented as a plurality of round operations (Round 1, Round 2, ..., Round n), and internal encoding may be applied between each round operations. However, F ^-1 may be applied as an inverse function of the outer encoding F to the input of the first round operation, and the outer encoding G may be applied to the output of the last round operation. In some cases, the external encodings F and G may be different from each other.

6 is an exemplary diagram illustrating an anti-inversion function.

Referring to FIG. 6, an anti-inversion layer may perform an operation of generating an output block Y from an input block X. In particular, the anti-inversion function can guarantee safety even if both the algorithm and the intermediate value are disclosed. However, in the process of recovering the input block X from the output block Y, a private key, which is private information, is essentially required, and the execution process needs to be protected through obfuscation or the like.

The anti-inversion function can provide a faster execution time than public key encryption such as RSA in terms of efficiency, and can generate an output block Y having a size relatively larger than the size of the input block X. In addition, the anti-inversion function can provide a much faster execution time than decryption of the public key encryption when recovering the input block X using the private key K. For example, the anti-inversion function may correspond to a graph-based encoding function.

Referring to FIG. 7, the encryption encoding apparatus 130 may apply an anti-inversion function to the output of the last round in the white box encryption process. In particular, the cryptographic encoding apparatus 130 may divide the output of the last round into a plurality of cryptographic blocks X1 and X2, and apply the anti-inversion function to only some of the cryptographic blocks X1. As a result, the encryption encoding device 130 is the output of the anti-inversion function (Y1) and the final cipher text (Y1 + Y2, Y2 = X2) consisting of the remaining encryption block (X2) to which the anti-inversion function is not applied. Can be provided as output.

In one embodiment, the encryption encoding apparatus 130 may further include a ciphertext decoding unit 370 that applies a decoding function to the final ciphertext to recover the original ciphertext for the encoded ciphertext. In this case, the ciphertext decoding unit 370 may be implemented independently from the cipher encoding apparatus 130. The ciphertext decoding unit 370 performs a first step of applying the inverse function of the anti-inversion function to some blocks Y1 constituting the final ciphertext (Y1+Y2) and external encoding the encoded ciphertext (X1+X2). It may consist of a second step of applying the inverse function of the function. In particular, in the case of the first step, the secret key K is required, and if there is no secret key K, recovery from the cipher block Y1 to the cipher block X1 is impossible.

8 is an exemplary diagram illustrating an anti-inversion decoding process.

Referring to FIG. 8, the encryption encoding apparatus 130 may apply an anti-inversion function in a white box encryption process. In the white box encryption process, the encrypted ciphertext may be generated as an output by applying external encoding to the ciphertext in the last round operation (S810). In this case, the external encoding G applied to the ciphertext generated as a result of the last round operation may be designed in a manner in which a linear transform is applied after nonlinear transformation in units of bytes.

In an embodiment, the encryption encoding apparatus 130 may perform anti-inversion encoding through the anti-inversion function application unit 350 (S830). Anti-inversion encoding divides the encoded ciphertext into two cipher blocks (X1, X2), applies the anti-inversion function to one cipher block (X1), and generates the final ciphertext (Y1, Y2). It may correspond to a process, and can be expressed as (Y1, Y2) = (AF(X1), X2). Accordingly, the encryption encoding apparatus 130 may provide the final encrypted text (Y1, Y2) as an output of white box encryption.

In an embodiment, the encryption encoding apparatus 130 may perform anti-inversion decoding through the ciphertext decoding unit 370 (S850). Anti-inversion decoding may correspond to the process of obtaining the original ciphertext from the outputs (Y1, Y2) of white box encryption, and more specifically, obtaining the cipher block (X1) from the cipher block (Y1) using the secret key K. The first step of performing and the second step of obtaining the encrypted text by applying the inverse function of the external encoding G (G ^-1 ) to the encoded ciphertext (X1, X2) may be performed. In particular, the first step can be expressed as X1 = AF_inv(Y1, K), and the anti-inversion decoding can be performed in an obfuscated area or a safe outside.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention within the scope not departing from the spirit and scope of the present invention described in the following claims. You will understand that you can do it.

본 발명을 지원한 국가연구개발사업National R&D project that supported the present invention

Assignment identification number: 1425133005

Department Name: Small and Medium Venture Business Department

Research and management professional institution: Small and Medium Business Technology Information Promotion Agency

Research Project Name: Industry-Academic Research Collabo R&D Project

Research Project Title: Development of security credential management technology based on WBC encryption technology for M3 MCU class IoT devices to strengthen device security credential management

Contribution Rate: 1/1

Organizer: Dream Security Co., Ltd.

Research Period: 2019.06.17~2020.02.16

[Explanation of code]

100: Whitebox encryption encoding system

110: user terminal 130: encryption encoding device

150: database

210: processor 230: memory

250: user input/output unit 270: network input/output unit

310: plain text receiving unit 330: encryption operation unit

350: anti-inversion function application unit 370: ciphertext decoding unit

390: control unit

510: plain text 530: cipher text

Claims

A plaintext receiver for receiving the encoded plaintext;

An encryption operation unit that generates an encoded ciphertext as an output through a white box encryption process using the encoded plaintext as an input; And

Dividing the encoded ciphertext into a plurality of cipher blocks and applying an anti-inversion function to any one of the plurality of cipher blocks to generate a final ciphertext, the anti-inversion function When an output block is generated from an input block and a secret key is applied to the output block, an anti-inversion function is applied that is implemented to recover the input block and provides one-wayness to the white box encryption process. White box encryption encoding device using an anti-inversion function including part.
The method of claim 1, wherein the encryption operation unit

A white box encryption apparatus using an anti-inversion function, characterized in that an iterative operation on a plurality of round functions implemented as a look-up table is applied as the white box encryption process.
The method of claim 2, wherein the encryption operation unit

A white box encryption apparatus using an anti-inversion function, characterized in that applying a nonlinear encoding function as an internal encoding in a step before and after each of the plurality of round functions.
The method of claim 3, wherein the encryption operation unit

An apparatus for encoding white box encryption using an anti-inversion function, characterized in that an external encoding function different from the internal encoding is applied to an output of the last round function among the plurality of round functions.
The method of claim 1, wherein the anti-inversion function application unit

A white box encryption apparatus using an anti-inversion function, characterized in that the output block of the anti-inversion function is connected with the rest of the plurality of encryption blocks to generate the final cipher text.
The method of claim 1,

And a ciphertext decoding unit that applies a decoding function to the final ciphertext and recovers the original ciphertext for the encoded ciphertext.
The method of claim 6, wherein the ciphertext decoding unit

Using an anti-inversion function, characterized in that the inverse function of the anti-inversion function is applied to the output block of the anti-inversion function in the final ciphertext, and is restored to the first cipher block. Whitebox cryptographic encoding device.
The method of claim 7, wherein the ciphertext decoding unit

White box encryption encoding using an anti-inversion function, characterized in that the entire cipher block including the first cipher block and the remaining cipher blocks of the final ciphertext is restored to the original ciphertext by applying an inverse function of an external encoding function Device.
In the method performed in a white box encryption encoding device,

Receiving the encoded plaintext;

Generating an encoded ciphertext as an output through a white box encryption process using the encoded plaintext as an input; And

Dividing the encoded ciphertext into a plurality of cipher blocks and applying an anti-inversion function to any one of the plurality of cipher blocks to generate a final ciphertext, the anti-inversion function When an output block is generated from an input block and a secret key is applied to the output block, the input block is implemented to be recoverable to provide one-wayness to the white box encryption process. Whitebox encryption method using inversion function.