KR102019182B1 - Method for controlling white-box cipher mode of operations which is computer-executable and apparatus of the same - Google Patents

Abstract

The present invention provides a computer-implemented lightweight whitebox encryption method comprising the steps of: (a) generating a plain text, (b) generating a whitebox cryptographic GFN (Generalized Feistel Network) generated as a lookup table with the round function internally encoded with a round key. And (c) providing the ciphertext by providing the externally encoded plaintext to the whitebox encrypted GFN.

Description

METHOD FOR CONTROLLING WHITE-BOX CIPHER MODE OF OPERATIONS WHICH IS COMPUTER-EXECUTABLE AND APPARATUS OF THE SAME}

The present invention relates to an encryption operation mode control technology, and more particularly, to a computer-implemented white box encryption operation mode control method and apparatus capable of safely and efficiently processing multiple blocks using a white box encryption.

Block cipher modes of operation refers to a procedure for repeatedly and securely using a block cipher under one key. Since block ciphers operate in units of blocks of a specific length, in order to encrypt variable length data, the ciphers must first be divided into unit blocks, and then, how to encrypt the blocks is determined. Representative examples of the block cipher operation method include electronic codebook (ECB) operation method, cipher-block chaining (CBC) operation method, counter (CTR) operation method, XEX-based tweaked-codebook operation method. mode with ciphertext stealing). The XTS operation method will be described in more detail with reference to FIG. 1.

1 is a block diagram showing an XTS operation method.

In FIG. 1, the XTS operation scheme uses an XEX (XOR-Encrypt-XOR) structure and uses two keys. The XTS operation method updates the XOR value for each block, and if the plaintext is not divided into blocks, the plaintext and the ciphertext are the same length using the structure that fills in the gap from the last ciphertext and then twists the final ciphertext. Lose. This XTS operation method is XTS mode is mainly used to encrypt the data part in disk encryption software (TrueCrypt, VeraCrypt, BestCrypt, dm-crypt, etc.) There is a characteristic.

Such a conventional XTS operation method has a disadvantage of being vulnerable to a white box attack during encryption and decryption.

The block cipher operated in the above-described block cipher operation method is based on a black box encryption mechanism operating under the assumption that the encryption key is securely maintained. In contrast, whitebox cryptography is based on a whitebox encryption mechanism that prevents an attacker from easily inferring a cryptographic key, even when internal operations are exposed. This will be described in more detail with reference to FIG. 2.

2 is a diagram illustrating a basic concept of white box encryption.

In Fig. 2, the whitebox encryption technique makes the encryption key easier even if the attacker analyzes the internal operation by hiding the algorithm into a large lookup table and hiding the encryption key therein with the software algorithm implemented in the encryption algorithm. Do not allow inference. More specifically, the whitebox encryption technique performs the encoding process (Mi) and the decoding process (Mi) ^-1 internally by using separate tables so that intermediate values are not exposed, and consequently, by offsetting encoding and decoding. The intermediate data and key of the round operation can be safely hidden from the attacker by setting the same as the result of only the encryption operation (Xi).

These whitebox ciphers can provide stronger security than block ciphers, but they have some disadvantages in terms of speed and memory.

Conventional cryptographic operation techniques can process whitebox cryptography for a single block, but there is a lack of an operation mode for efficiently processing and operating whitebox cryptography for multiple blocks, and the development thereof is required.

Korean Patent Laid-Open No. 10-2011-0042419 (2011.04.27) relates to a method for operating a block cipher applicable to multimedia, and is a mixed model using a CTR mode and a CBC mode at the same time. DCBC (Discrete CBC) mode, which operates an initial vector as a chain of counters, where, within the superblock, the decryption and steps in the same manner as the conventional CBC mode and the initial vector used for each superblock are incremented in the conventional CTR mode. It includes a rule, and because the encryption and decryption is made in the unit of the superblock, it is possible to encrypt and decrypt only the desired superblock, parallel processing, it is characterized in that the random access to the superblock unit.

Korean Patent Registration No. 10-1623503 (2016.05.17) relates to an apparatus and method for implementing a white box cryptography of an EL block cipher, and comprising a plurality of tables of cryptographic algorithms including cryptographic keys in the source code or memory area of the cryptographic algorithm. The present invention provides an apparatus and method for implementing an LEA block cipher white box cipher that can prevent a cipher key from being searched through, a plain text input unit that receives an encoded encoded plain text, and an encoding input from the plain text input unit. A round function unit for receiving a result of a round function or a previous round function unit and performing a modular addition and rotation operation based on a random table to output a result of distributed processing of round key operation positions using a linear transformation, and the round function unit Round function execution is completed for all round keys among outputs processed by There is consists to the result of encoding including a ciphertext outputted cipher text output for outputting.

Korean Patent Publication No. 10-2011-0042419 (2011.04.27) Korean Patent Registration No. 10-1623503 (2016.05.17)

An embodiment of the present invention is to provide a computer-implemented white box encryption operation mode control method and apparatus that can safely and efficiently process multiple blocks using a white box encryption.

One embodiment of the present invention can control the whitebox encryption process for multiple blocks based on the XEX-based tweaked-codebook mode with ciphertext stealing (XTS) operating mode to minimize speed degradation and to secure computer execution against whitebox attacks The present invention provides a method and apparatus for controlling a white box encryption operation mode.

According to an embodiment of the present invention, a computer-executable white box encryption operation mode that improves user convenience by determining whether to perform white box encryption on a plurality of encryption keys according to a security mode to enable adjustment between encryption speed and security. It is intended to provide a control method and apparatus.

Among embodiments, a computer-implemented whitebox cryptographic operation mode control method includes (a) receiving a plurality of encryption keys associated with a multi-block cipher, and (b) relating to one of the plurality of encryption keys in a first security mode. Encrypting the block cipher by performing whitebox encryption, (c) receiving a plurality of fragmented plaintexts, and (d) reflecting the encrypted block cipher to the remainder of the plurality of encryption keys and Generating a plurality of fragment ciphertexts by block cipher encryption.

Step (b) may include performing block cipher encryption on one of the plurality of encryption keys in a second security mode.

Step (b) may include performing whitebox encryption on one of the plurality of encryption keys having the least number of encryptions (hereinafter, referred to as a common encryption key).

Step (c) may comprise externally encoding the received plurality of split plain texts prior to the block cipher encryption.

The step (d) may include externally encoding the plurality of fragment ciphertexts after the block cipher encryption.

The step (b) further includes the step of generating an encoding conversion table defining a plurality of encoding conversion schemes in the process of performing the white box encryption, wherein the computer-implementable white box encryption operation mode control method includes (c) and In step (d), the method may include performing an external encoding on each of the plurality of split plaintext and split ciphertext based on the encoding conversion table.

The step (d) may include performing an XOR operation between each of the encrypted block cipher and the plurality of externally encoded fragmented plaintexts and providing a result of performing the operation as an input for performing the block cipher encryption. Can be.

The step (a) may include receiving two keys used in the XTS-based tweaked-codebook mode with ciphertext stealing (XTS) mode as the plurality of encryption keys.

The step (b) may include performing the white box encryption based on a white box (WB) -advanced encryption standard (AES), a data encryption standard (WB-DES), or a light weight encryption algorithm (WB-LEA). Can be.

In one or more embodiments, the apparatus for controlling a whitebox encryption operation mode may include: an encryption key receiver configured to receive a plurality of encryption keys associated with a multi-block cipher, and performing a whitebox encryption on one of the plurality of encryption keys in a first security mode. A white box encryption execution unit for encrypting a cipher, a split plaintext receiver for receiving a plurality of divided plaintexts, and the encrypted block cipher are reflected in the remaining ones of the plurality of encryption keys and the plurality of divided plaintexts are block cipher encryption. And a split ciphertext generator for generating a plurality of split ciphertexts.

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

A computer-implemented white box encryption operation mode control method and apparatus according to an embodiment of the present invention can safely and efficiently process multiple blocks using white box encryption.

A computer-implemented white box encryption operating mode control method and apparatus according to an embodiment of the present invention may control white box encryption processing for multiple blocks based on an XEX-based tweaked-codebook mode with ciphertext stealing (XTS) operating mode. It can minimize speed degradation and is safe against white box attacks.

The method and apparatus for controlling computer-implemented whitebox encryption operation mode according to an embodiment of the present invention determine whether to perform whitebox encryption on a plurality of encryption keys according to the security mode so that the control between encryption speed and security is possible. User convenience can be improved.

1 is a block diagram showing an XTS operation method.
2 is a diagram illustrating a basic concept of white box encryption.
3 is a block diagram illustrating a configuration of an apparatus for controlling a white box encryption operation mode according to an embodiment of the present invention.
FIG. 4 is a block diagram illustrating a process in which the white box encryption operation mode control device of FIG. 3 operates in a first security mode among white box encryption operation modes for multiple blocks.
FIG. 5 is a block diagram illustrating an embodiment of a process of generating a plurality of divided cipher texts according to a security mode by the apparatus for controlling a white box encryption operation mode of FIG. 3.

Description of the present invention is only an embodiment for structural or functional description, the scope of the present invention should not be construed as limited by the embodiments described in the text. That is, since the embodiments may be variously modified and may have various forms, the scope of the present invention should be understood to include equivalents capable of realizing the technical idea. In addition, the objects or effects presented in the present invention does not mean that a specific embodiment should include all or only such effects, the scope of the present invention should not be understood as being limited thereby.

On the other hand, the meaning of the terms described in the present application should be understood as follows.

Terms such as "first" and "second" are intended to distinguish one component from another component, and the scope of rights should not be limited by these terms. For example, the first component may be named a second component, and similarly, the second component may also be named a first component.

When a component is referred to as being "connected" to another component, it should be understood that there may be other components in between, although it may be directly connected to the other component. On the other hand, when a component is referred to as being "directly connected" to another component, it should be understood that there is no other component in between. On the other hand, other expressions describing the relationship between the components, such as "between" and "immediately between" or "neighboring to" and "directly neighboring to", should be interpreted as well.

Singular expressions should be understood to include plural expressions unless the context clearly indicates otherwise, and terms such as "comprise" or "have" refer to a feature, number, step, operation, component, part, or feature thereof. It is to be understood that the combination is intended to be present and does not exclude in advance the possibility of the presence or addition of one or more other features or numbers, steps, operations, components, parts or combinations thereof.

In each step, an identification code (e.g., a, b, c, etc.) is used for convenience of description, and the identification code does not describe the order of the steps, and each step clearly indicates a specific order in context. Unless stated otherwise, they may occur out of the order noted. That is, each step 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 code on a computer readable recording medium, and the computer readable recording medium includes all kinds of recording devices in which data can be read by a computer system. . Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, and the like, and are also implemented in the form of a carrier wave (for example, transmission over the Internet). It also includes. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

All terms used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. Generally, the terms defined in the dictionary used are to be interpreted to coincide with the meanings in the context of the related art, and should not be interpreted as having ideal or excessively formal meanings unless clearly defined in the present application.

3 is a block diagram illustrating a configuration of an apparatus for controlling a white box encryption operation mode according to an embodiment of the present invention.

Referring to FIG. 3, the apparatus for controlling white box encryption operation mode 300 may include an encryption key receiver 310, a white box encryption performer 320, a split plaintext receiver 330, a split ciphertext generator 340, and a controller ( 350).

The white box encryption operation mode control device 300 may correspond to a computing device capable of controlling the white box encryption operation mode for multiple blocks, and in one embodiment, is implemented as a desktop, a tablet PC, a notebook, or a smartphone. Can be.

The encryption key receiver 310 may receive a plurality of encryption keys. The following contents will be described in more detail with reference to FIG. 4.

FIG. 4 is a block diagram illustrating a process in which the white box encryption operation mode control device of FIG. 3 operates in a first security mode among white box encryption operation modes for multiple blocks.

In FIG. 4, the encryption key receiver 310 may receive a plurality of encryption keys 410 associated with a multi-block cipher. According to an embodiment, the encryption key receiver 310 may receive two keys used in the XEX-based tweaked-codebook mode with ciphertext stealing (XTS) mode as the plurality of encryption keys 410. For example, the encryption key receiver 310 may receive the first encryption key 410a and the second encryption key 410b used in the XTS mode.

The whitebox encryption performing unit 320 may encrypt the block cipher by performing whitebox encryption on one of the plurality of encryption keys 410 in the first security mode. More specifically, the whitebox encryption performing unit 320 may determine whether to perform whitebox encryption on the plurality of encryption keys 410 based on the plurality of security modes including the first and second security modes. In one embodiment, the whitebox encryption performing unit 320 may perform whitebox encryption on one of the plurality of encryption keys 410 in the first security mode, and the plurality of encryption keys 410 in the second security mode. Block cipher encryption (block cipher encryption) can be performed. In one embodiment, the whitebox encryption performing unit 320 may perform whitebox encryption on all of the plurality of encryption keys 410 in the third security mode. The white box encryption performing unit 320 may provide the divided ciphertext generation unit 340 with an encrypted block cipher in which white box encryption is performed and another encryption key in which white box encryption is not performed.

Accordingly, the white box encryption execution unit 320 may expose the remaining encryption key and encoding information even if the corresponding encryption key is exposed by an attacker in a security mode in which the white box encryption is performed only for one of the plurality of encryption keys 410. Because it is not exposed, it has a safe effect against white box attacks and does not perform white box encryption on all encryption keys, thereby preventing the degradation of the overall encryption speed. In addition, the white box encryption execution unit 320 enhances security by performing white box encryption on all encryption keys according to the security mode, or instead of lowering security by not performing white box encryption on all encryption keys. The operating mode may be selectively controlled in consideration of the direction of increasing the speed.

In one embodiment, the whitebox encryption performing unit 320 may perform whitebox encryption on one of the plurality of encryption keys 410 having the least number of encryptions (hereinafter, referred to as a common encryption key). In one embodiment, the whitebox encryption performing unit 320 may determine the encryption key having the smallest ratio used in the entire encryption process as the common encryption key, and in another embodiment, the encryption key used first in the entire encryption process May be determined as the common encryption key.

In one embodiment, the whitebox encryption performing unit 320 performs a first encryption key 410a and a second encryption key 410b used in the XTS mode in a first security mode that performs whitebox encryption on a single encryption key. May be selected, and for example, the second encryption key 410b may be determined as the common encryption key by determining the second encryption key 410b which is less frequently used as an input seed for block cipher encryption in the entire encryption process. Based on this, whitebox encryption for a single block can be performed. Accordingly, the white box encryption performing unit 320 may reduce the overall speed degradation through the white box encryption on the second encryption key 410b while providing the attacker with the first encryption key 410a (for example, Key1). Even if is exposed, the second encryption key 410b (for example, Key2) and the encoding information can be hidden to protect the attacker from being able to recognize the plain text from the cipher text.

In one embodiment, the white box encryption execution unit 320 is a white box encryption execution unit 320 is WB (White Box) -AES (Advanced Encryption Standard), WB-DES (Data Encryption Standard) or WB-LEA (Lightweight) Whitebox encryption can be performed based on Encryption Algorithm. For example, the white box encryption execution unit 320 may generate a white box table in which an encryption method for the second encryption key 410b is defined based on WB-AES, WB-DES, or WB-LEA. in the part of the identification number 420, on the basis of the white-box table by performing the white-box cryptographic about _{T 1 (G (T 1)} ) can output a T ₁ '.

In one embodiment, the whitebox encryption performing unit 320 may generate an encoding conversion table that defines a plurality of encoding conversion schemes in the process of performing whitebox encryption. The whitebox encryption performing unit 320 may perform external encoding during the entire encryption process based on the encoding conversion table. In one embodiment, the whitebox encryption performing unit 320 may generate the encoding conversion table, the XOR table necessary for the subsequent encryption process, and the α update table together during the whitebox encryption. In one embodiment, the whitebox encryption performing unit 320 may store the whitebox table, the XOR table, and the α update table for the generated second encryption key 410b in memory, and because they are random tables, It is safe even if it is stored in, so it can provide both ease of implementation and safety at the same time.

In an embodiment, the whitebox encryption performing unit 320 may determine at least one encryption key for performing whitebox encryption among the plurality of encryption keys 410 based on Equation 1 below. More specifically, the white box encryption performing unit 320 may calculate an encryption key determination index (c) with respect to a specific encryption key based on Equation 1 below, and when the encryption key determination index (c) is less than 1 Only you can decide to perform whitebox encryption on that encryption key. For example, the white box encryption execution unit 320 may assume that the following s is set to 0.3 by the user, respectively, to each of the two encryption keys 410a and 410b used in the XTS mode. The number of times the encryption key used as the input seed for the block cipher encryption in the entire encryption process can be detected as 3 and 1, respectively, and n = 3, t = 4, and s = 0.3 for the first encryption key 410a. By applying c = 2.5, it can be determined that white box encryption on the first encryption key 410a is not performed, and n = 1, t = 4, s = 0.3 on the second encryption key 410b. By applying c = 0.83 it can be determined to perform the white box encryption on the second encryption key (410b).

[Equation 1]

(Where n denotes the number of times the encryption key is used as an input seed for block cipher encryption during the entire encryption process, t denotes the total number of times of use of the entirety of the plurality of encryption keys 410, and s is set by the user) A specific reference ratio that can be (represents a value greater than 0 and less than 1, for example, 0.3)

The divided plain text receiver 330 may receive a plurality of divided plain texts. More specifically, the divided plaintext receiver 330 may receive data as an encryption target as a plurality of divided plaintexts, and in a subsequent step, a ciphertext based on whitebox encryption for multiple blocks is generated based on the plurality of divided plaintexts. You can do that. For example, the divided plaintext receiver 330 may receive a plurality of divided plaintexts P ₁ , P ₂ , and P ₃ . In one embodiment, the length of each of the plurality of split plaintexts may be the same as the ciphertext.

The split plaintext receiver 330 may externally encode a plurality of split plaintexts received before block cipher encryption, and provide the split encoded plaintexts as an input to the split ciphertext generator 340. In an embodiment, the split plaintext receiver 330 may perform external encoding on each of the plurality of split plaintexts based on the encoding conversion table. For example, the divided plaintext receiver 330 receives the plurality of divided plaintexts P ₁ , P _2, and P ₃ and defines the plurality of divided plain texts as shown in the identification number 440 based on an encoding conversion table that defines a plurality of encoding conversion schemes. Perform outer encoding on P ₁ , P ₂ and P ₃ (F (P ₁ ), F (P ₂ ), F (P ₃ )) to externally encode split plaintexts P ₁ ′, P ₂ ′ and P Each ₃ 'can be output and reflected in subsequent operations.

In one embodiment, the split plaintext receiver 330 may be secured by applying obfuscation to the encoding conversion table used in the external encoding process to be applied to the plaintext and ciphertext, and to apply the external encoding to the plaintext and the external The process of decoding the ciphertext with the encoding applied can be protected by obfuscation.

The split ciphertext generation unit 340 generates a plurality of split ciphertexts by reflecting the block cipher encrypted through the white box encryption to the rest of the plurality of encryption keys 410 and block cipher ciphering the plurality of split plaintexts. Can be.

In one embodiment, the split ciphertext generation unit 340 may operate a white box encryption operation mode for multiple blocks based on an XTS-based tweaked-codebook mode with ciphertext stealing (XTS) mode, as shown in FIG. 4. have. More specifically, the divided cipher text generation unit 340 receives a block cipher encrypted through white box encryption based on a common encryption key from the white box cipher 320, a block cipher encryption process (identification number) 430 ~ 480).

In one embodiment, the split ciphertext generation unit 340 performs an XOR operation between each of the encrypted block cipher and the plurality of externally encoded split plaintexts and provides the result of performing the operation as an input for performing block cipher encryption. Can be. For example, the split ciphertext generation unit 340 is the block cipher T ₁ 'encrypted through the white box encryption through the second encryption key 410b and the externally encoded split plaintext P ₁ ' as in the identification number 450a. The XOR operation may be performed, and the output result of the XOR operation may be provided as an input to a block cipher encryption process using the first encryption key 410a as shown in the identification number 460a.

을 출력할 수 있다. 일 실시예에서, 도 4에 표기된

은 XOR 테이블을 기초로 수행되는 XOR 연산을 의미한다.In one embodiment, the split ciphertext generator 340 may generate each of the plurality of split ciphertexts by performing block cipher encryption based on AES, DES, or LEA. For example, the split ciphertext generation unit 340 encrypts the block cipher based on the LEA based on the block cipher technology using the result output through the XOR operation such as the identification number 450a and the first encryption key 410a. C ₁ can be outputted, and the block cipher T ₁ 'encrypted through the white box encryption through the second encryption key 410 b as shown in the identification number 470a is divided by the XOR operation on the above output C ₁ . cryptogram

You can output In one embodiment, shown in FIG.

Denotes an XOR operation performed based on the XOR table.

In one embodiment, the split ciphertext generation unit 340 may be reflected in the process of performing the block cipher encryption for the next block of the multi-block by performing the α update operation on the encrypted block cipher based on the α update table. . For example, the split ciphertext generation unit 340 performs the α update primary operation on the block cipher T ₁ ′ encrypted through whitebox encryption through the second encryption key 410b, as shown in the identification number 430a. Provides the execution result (G (T ₂ ) = T ₂ ') as an input to the next block, and performs the result of the α update operation (G (T ₂₎ as in the identification number 430b during the process of block cipher encryption for the next block. The α update quadratic operation regarding) = T ₂ ′) may be performed to provide a corresponding quadratic result G (T ₃ ) = T ₃ ′ as an input to the next block.

에 관한 외부 인코딩을 수행하여 외부 인코딩된 분할 암호문을 출력할 수 있다.In one embodiment, the split ciphertext generator 340 may perform an external encoding on each of the plurality of split ciphertexts based on an encoding conversion table for externally encoding the plurality of split ciphertexts after block cipher encryption. For example, the divided cipher text generation unit 340 is divided cipher text, such as identification number 480a

An externally encoded split ciphertext may be output by performing an external encoding on the.

The control unit 350 may control the overall operation of the apparatus for controlling the white box encryption operation mode 300, and generates an encryption key receiver 310, a white box encryption performer 320, a split plaintext receiver 330, and a split ciphertext. The data flow between the units 340 may be controlled. In an embodiment, the controller 350 may be implemented as a central processing unit (CPU) of the apparatus for controlling white box encryption operation mode 300.

FIG. 5 is a block diagram illustrating an embodiment of a process of generating a plurality of divided cipher texts according to a security mode by the apparatus for controlling a white box encryption operation mode of FIG. 3. The encryption operation mode control method, which may include the following steps, is computer executable.

In FIG. 5, the encryption key receiving unit 310 may receive a plurality of encryption keys (step S505). The whitebox encryption performing unit 320 may perform whitebox encryption on one of the plurality of encryption keys 410 in the first security mode (steps S510 to S530), and the plurality of encryption keys (2) in the second security mode. 410 may perform block cipher encryption (steps S535 to S550).

In the first security mode, the whitebox encryption performing unit 320 may encrypt the block cipher by performing whitebox encryption on one of the plurality of encryption keys 410 (step S510). In one embodiment, the whitebox encryption performing unit 320 sets the second encryption key 410b having the least number of encryptions among the first and second encryption keys 410 used in the XTS mode as a common encryption key, and sets the second encryption key. Whitebox encryption may be performed on the encryption key 410b. The split plaintext receiver 330 may receive a plurality of split plaintexts and provide a plurality of externally encoded split plaintexts as input to the split ciphertext generator 340 based on an encoding conversion table (step S515). The division ciphertext generation unit 340 reflects the block cipher encrypted through the white box encryption to the rest of the plurality of encryption keys 410 (step S520), and the multi-block based on the rest of the plurality of encryption keys 410. Block cipher encryption may be performed to generate a plurality of fragment ciphertexts (step S525). The split cipher text generation unit 340 may perform external encoding on each of the plurality of split cipher texts based on the encoding conversion table after block cipher encryption (step S530).

In the second security mode, the whitebox encryption performing unit 320 may encrypt the block cipher by performing block cipher encryption on one of the plurality of encryption keys 410 (step S535). In one embodiment, the white box encryption execution unit 320 may perform block cipher encryption on the one based on AES, DES or LEA. The split plaintext receiver 330 may receive a plurality of split plaintexts and generate a plurality of externally encoded split plaintexts based on an encoding conversion table (step S540). The split ciphertext generation unit 340 may generate a plurality of split ciphertexts by performing block cipher encryption on multiple blocks (step S545). The split ciphertext generator 340 may perform external encoding on each of the plurality of split ciphertexts based on the encoding conversion table after block cipher encryption (step S550).

In one embodiment, the white box encryption operation mode control apparatus 300 may further include a third security mode for performing white box encryption on all of the plurality of encryption keys 410.

In one embodiment, the white box encryption operation mode control device 300 controls the operation mode of the white box encryption for multiple blocks to ensure safety through white box encryption that is safe against white box attack while at the same time speed according to white box encryption This can minimize degradation and memory problems that require a lot of space.

In one embodiment, the white box encryption operation mode control device 300 applies white box encryption to a low encryption key in the entire encryption process to enhance the security while operating efficiently in terms of encryption speed and memory space. Can be controlled.

In one embodiment, the white box encryption operation mode control apparatus 300 may enhance the security than using a fixed encoding scheme by forming an encoding pool for the α update operation and the XOR operation to which various encodings are applied.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

300: white box encryption operation mode control device
310: encryption key receiving unit 320: white box encryption execution unit
330: Split plaintext receiver 340: Split ciphertext generator
350: control unit

Claims (10)

(a) receiving a plurality of encryption keys associated with the multi-block cipher and directly participating in the operation of the particular block cipher algorithm;
(b) encrypting a block cipher by performing whitebox encryption on one of the plurality of encryption keys in a first security mode, and generating and storing a table relating to a plurality of encoding conversion schemes in the process of performing the whitebox encryption; Doing;
(c) receiving a plurality of split plain texts; And
(d) reflecting the encrypted block cipher in an operation of the specific block cipher algorithm and block cipher encrypting the plurality of divided plain texts to generate a plurality of divided cipher texts. How to control box encryption operation mode.
The method of claim 1, wherein step (b)
And performing block cipher encryption on one of the plurality of cipher keys in a second security mode.
The method of claim 1, wherein step (b)
And performing whitebox encryption on one of the plurality of encryption keys having the least number of encryptions (hereinafter, common encryption key).
The method of claim 1, wherein step (c)
And externally encoding the received plurality of fragmented plaintexts prior to the block cipher encryption.
The method of claim 1, wherein step (d)
And externally encoding the plurality of split ciphertexts after the block cipher encryption.
The method of claim 4 or 5, wherein step (b)
Generating an encoding conversion table defining a plurality of encoding conversion schemes during the whitebox encryption;
And (c) and (d) performing external encoding on each of the plurality of split plaintext and split ciphertexts based on the encoding conversion table.
The method of claim 6, wherein step (d)
Performing an XOR operation between each of the encrypted block cipher and the plurality of externally encoded fragmented plaintexts, and providing a result of performing the operation as an input for performing the block cipher encryption. Operation mode control method.
The method of claim 1, wherein step (a)
And receiving, as the plurality of encryption keys, two keys used in an XEX-based tweaked-codebook mode with ciphertext stealing (XTS) mode.
The method of claim 1, wherein step (b)
And executing the white box encryption based on White Box (WB) -Advanced Encryption Standard (AES), Data Encryption Standard (WB-DES) or Lightweight Encryption Algorithm (WB-LEA). How to control whitebox encryption mode of operation.
An encryption key receiver for receiving a plurality of encryption keys associated with the multi-block cipher and directly participating in the operation of a particular block cipher algorithm;
A white box encrypts a block cipher by performing whitebox encryption on one of the plurality of encryption keys in a first security mode, and generates and stores a table relating to a plurality of encoding conversion schemes during the whitebox encryption. An encryption performing unit;
A divided plain text receiver for receiving a plurality of divided plain texts; And
A white box encryption operation mode including a divided ciphertext generator configured to reflect the encrypted block cipher in an operation process of the specific block cipher algorithm and generate a plurality of divided ciphertexts by block cipher encryption of the plurality of divided plaintexts controller.

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