KR20190016285A - Method for controlling white-box cipher mode of operations which is computer-executable and apparatus of the same - Google Patents

Abstract

The present invention relates to a computer-executable lightweight white-box ciphering method which comprises the steps of: (a) generating a plain text; (b) generating a white-box cipher type generalized Feistel network (GNF) generated as a lookup table where a round function is internally encoded with a round key; and (c) providing an externally encoded plain text to the white-box cipher type GNF to provide a cipher text.

Description

TECHNICAL FIELD [0001] The present invention relates to a computer-executable white-box cryptographic operation mode control method and apparatus,

The present invention relates to a cryptographic operation mode control technique, and more particularly, to a computer-executable white box cryptographic operation mode control method and apparatus capable of safely and efficiently processing multiple blocks using white box cryptography.

Block cipher modes of operation refers to the process of repeatedly and securely using block ciphers under one key. Since the block cipher operates in block units of a specific length, in order to encrypt variable-length data, it is necessary to divide them into unit blocks and determine how to encrypt the blocks. At this time, the encryption method of blocks is referred to as an operation method. Typical examples of the block cipher maneuvering method include an electronic codebook (ECB) operating method, a cipher-block chaining (CBC) operating method, a counter (CTR) operating method, an XEX-based tweaked- mode with ciphertext stealing). The XTS operation method will be described in more detail with reference to FIG.

1 is a block diagram illustrating an XTS operation method.

In FIG. 1, the XTS operating scheme uses an XOR (XOR-Encrypt-XOR) structure and uses two keys. The XTS operation method updates the XOR value for each block. If the plaintext is not divided into block units, it uses the structure that twists the final ciphertext after filling the missing part from the last ciphertext, Loses. In XTS mode, XTS mode is mainly used for encrypting data in disk encryption software (TrueCrypt, VeraCrypt, BestCrypt, dm-crypt, etc.), and even if the same data is used, Feature.

Such a conventional XTS operation method is vulnerable to a white-box attack during encryption and decryption.

The block cipher operating in the above-described block cipher maneuvering scheme is based on a black box cipher mechanism operating under the assumption that the cipher key is securely maintained. In contrast, white-box cryptography is based on a white-box cryptographic mechanism that prevents an attacker from easily guessing a cryptographic key even if its internal behavior is exposed. This will be described in more detail with reference to FIG.

2 is a diagram for explaining the basic concept of white-box encryption.

In FIG. 2, the white-box encryption technique makes an algorithm a large look-up table and hides the encryption key in an obfuscation state with a software-implemented encryption algorithm, so that even if the attacker analyzes the internal operation, Avoid analogy. More specifically, the white box encryption technique internally performs encoding (Mi) and decoding (Mi) ^-1 on a separate table so that the intermediate value is not exposed, and as a result, The intermediate data and the key of the round operation can be safely hidden from the attacker.

Such a white-box password can provide more security than a block cipher, but has a disadvantage in terms of efficiency and speed in terms of speed and memory.

Conventional cryptographic operation techniques can handle a white-box cipher for a single block, but there is no operating mode for efficient processing and operation of a white-box cipher for multi-blocks, and development thereof is required.

Korean Patent Laid-Open No. 10-2011-0042419 (Apr. 27, 2011) discloses a block cipher method applicable to multimedia. It is a mixed model using both CTR mode and CBC mode and is divided into super blocks. A DCBC (Discrete CBC) mode in which the initial vector is operated as a chain counter, wherein in the super block, the encryption decoding and the step in the same manner as the conventional CBC mode, and the initial vector used in each super block, Rules are included and the encryption / decryption is performed in units of the above superblocks. Therefore, only the desired superblock can be decrypted, parallel processing is possible, and random access is possible in units of superblocks.

Korean Patent No. 10-1623503 (2016.05.17) relates to an apparatus and method for implementing a white-box encryption of an LEA block cipher. The encryption algorithm including the encryption key is composed of a plurality of tables, The present invention provides an apparatus and method for implementing a white-box cipher of an LEA block cipher that can prevent a cipher key from being searched for through a search of a plaintext input unit, a plain text input unit that receives an encoded plain text, A round function unit for receiving a result of the round function performed in the plain text or immediately before and performing a modular addition and a rotation operation based on the random table and outputting a result of the round key operation position dispersion processing using the linear transformation; The round function part for all the round keys among the output values processed in There is consists to the result of encoding including a ciphertext outputted cipher text output for outputting.

Korean Patent Publication No. 10-2011-0042419 (Apr. 27, 2011) Korean Patent No. 10-1623503 (May 2015)

One embodiment of the present invention seeks to provide a computer-executable white-box cryptographic operating mode control method and apparatus that can safely and efficiently process multiple blocks using white-box cryptography.

An embodiment of the present invention can control the white-box encryption processing for multiple blocks based on the XEX-based tweaked-codebook mode with ciphertext stealing (OSS) operating mode, thereby minimizing the speed degradation, And to provide a possible white-box encrypted operating mode control method and apparatus.

One embodiment of the present invention provides a computer-executable white-box cryptographic operation mode that improves user convenience by allowing the white-box encryption of a plurality of encryption keys to be performed according to a security mode, And to provide a control method and apparatus.

Among the embodiments, a computer-executable white-box cryptographic operating mode control method comprises the steps of: (a) receiving a plurality of cryptographic keys associated with a multi-block cryptographic key; (b) (C) receiving a plurality of split plaintexts; and (d) reflecting the encrypted block cipher to the rest of the plurality of encryption keys, and transmitting the plurality of split plaintexts And block cipher encryption to generate a plurality of divided ciphertexts.

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

The step (b) may include performing white-box encryption on one of the plurality of encryption keys having the smallest encryption number (hereinafter referred to as a common encryption key).

The step (c) may include the step of externally encoding the received plurality of divided plain texts before the block encryption.

The step (d) may include the step of externally encoding the plurality of divided ciphertexts after the block ciphering.

Wherein the step (b) further comprises generating an encoding conversion table that defines a plurality of encoding conversion schemes in the process of performing the white-box encryption, and the computer-executable lightweight white- ) Performing an outer encoding on each of the plurality of divided plain texts and the divided ciphertexts based on the encoding conversion table in the step (b).

The step (d) includes performing an XOR operation between the encrypted block cipher and each of the externally encoded plurality of divided plain texts to provide a result of performing the operation as an input for performing the block cipher encryption .

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

The step (b) includes performing the white-box encryption based on a WB (White Box) -AES (Advanced Encryption Standard), a WB-DES (Data Encryption Standard) or a WB-LEA (Lightweight Encryption Algorithm) .

In embodiments, the white-box cryptographic operating mode control device comprises an encryption key receiver for receiving a plurality of encryption keys associated with a multi-block cryptographic key, a white-box encryption mode for performing one of the plurality of encryption keys in the first security mode, A division plaintext receiving unit for receiving a plurality of divided plaintexts; and a memory unit for storing the encrypted block cipher on the rest of the plurality of encryption keys, and dividing the plurality of divided plaintexts into block cipher encryption ) To generate a plurality of divided ciphertexts.

The disclosed technique may have the following effects. It is to be understood, however, that the scope of the disclosed technology is not to be construed as limited thereby, as it is not meant to imply that a particular embodiment should include all of the following effects or only the following effects.

A computer-executable white-box cryptographic operating mode control method and apparatus according to an embodiment of the present invention can safely and efficiently process multiple blocks using white-box cryptography.

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

A computer-executable white-box cryptographic operation mode control method and apparatus according to an exemplary embodiment of the present invention determines whether to perform white-box encryption of a plurality of encryption keys according to a security mode, So that the user convenience can be improved.

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

The description of the present invention is merely an example for structural or functional explanation, and the scope of the present invention should not be construed as being limited by the embodiments described in the text. That is, the embodiments are to be construed as being variously embodied and having various forms, so that the scope of the present invention should be understood to include equivalents capable of realizing technical ideas. Also, the purpose or effect of the present invention should not be construed as limiting the scope of the present invention, since it does not mean that a specific embodiment should include all or only such effect.

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

The terms "first "," second ", and the like are intended to distinguish one element from another, and the scope of the right should not be limited by these terms. For example, 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.

It is to be understood that when an element is referred to as being "connected" to another element, it may be directly connected to the other element, but there may be other elements in between. On the other hand, when an element is referred to as being "directly connected" to another element, it should be understood that there are no other elements in between. On the other hand, other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

It is to be understood that the singular " include " or "have" are to be construed as including the stated feature, number, step, operation, It is to be understood that the combination is intended to specify that it does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

In each step, the identification code (e.g., a, b, c, etc.) is used for convenience of explanation, the identification code does not describe the order of each step, Unless otherwise stated, it may occur differently from the stated order. That is, each step may occur in the same order as described, may be performed substantially concurrently, or may be performed in 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 for storing data that can be read by a computer system . Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like, and also implemented in the form of a carrier wave (for example, transmission over the Internet) . In addition, the computer-readable recording medium may be distributed over network-connected computer systems so that computer readable codes 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 art to which this invention belongs, unless otherwise defined. Commonly used predefined terms should be interpreted to be consistent with the meanings in the context of the related art and can not be interpreted as having ideal or overly formal meaning unless explicitly defined in the present application.

3 is a block diagram illustrating a configuration of a white-box cryptographic operation mode control apparatus according to an embodiment of the present invention.

3, the white box cryptographic operation mode control apparatus 300 includes an encryption key receiving unit 310, a white box encryption performing unit 320, a divided plain text receiving unit 330, a divided cipher text generating unit 340, 350).

The white-box cryptographic operating mode control device 300 may correspond to a computing device capable of controlling a white-box cryptographic operating mode for multiple blocks, and in one embodiment may be implemented as a desktop, tablet PC, notebook, .

The encryption key receiving unit 310 can receive a plurality of encryption keys. The following contents will be described in more detail with reference to FIG.

4 is a block diagram illustrating a process in which the white-box cryptographic operation mode control apparatus shown in FIG. 3 operates in a first security mode among white-box cryptographic operation modes for multiple blocks.

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

The white-box encryption performing unit 320 may encrypt the block encryption by performing white-box encryption on one of the plurality of encryption keys 410 in the first security mode. More specifically, the white-box encryption performing unit 320 may determine whether to perform white-box 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 white-box cryptographic implementer 320 may perform white-box encryption on one of the plurality of cryptographic keys 410 in the first secure mode, and may perform the white-box encryption on the plurality of cryptographic keys 410 (Block cipher encryption). ≪ / RTI > In one embodiment, the white-box cryptographic implementation unit 320 may perform white-box 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 block encryption unit 340 with the encrypted block encryption in which the white box encryption is performed and the other encryption key in which the white box encryption is not performed.

Accordingly, even if the encryption key is exposed by the attacker in the security mode in which white-box encryption is performed for only one encryption key among the plurality of encryption keys 410, the white- The white box attack is safely effected, and the white box encryption is not performed on all the encryption keys, thereby preventing a decrease in the overall encryption speed. In addition, the white-box encryption performing unit 320 may perform white-box encryption on all the encryption keys according to the security mode, thereby enhancing security or not performing white-box encryption on all encryption keys, The operating mode can be selectively controlled in consideration of the direction of increasing the speed.

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

In one embodiment, the white-box encryption performing unit 320 may include a first encryption key 410a and a second encryption key 410b used in the XTS mode in a first security mode for performing white-box encryption on a single encryption key, For example, the second encryption key 410b, which is used less frequently as the input seed for the block encryption in the entire encryption process, is determined as the common encryption key, and the second encryption key 410b You can perform white-box encryption on a single block as a basis. Accordingly, the white-box encryption performing unit 320 can reduce the overall speed reduction through white-box encryption with respect to the second encryption key 410b, and send the first encryption key 410a (for example, Key1) The second encryption key 410b (e.g., Key2) and the encoding information can be hidden even if the second encryption key 410b is exposed, so that the attacker can protect the plaintext from the cipher text.

In one embodiment, the white-box cipher performing unit 320 performs a white-box cipher performing unit 320 such that the white-box cipher performing unit 320 performs encryption using a white box (AOB) -AES (Advanced Encryption Standard), a WB-DES (Data Encryption Standard) Encryption Algorithm). For example, the white-box encryption performing 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, (G (T ₁ )) T ₁ 'by performing white-box encryption on T ₁ in the part of identification number 420 based on the white box table.

In one embodiment, the white-box encryption performing unit 320 may generate an encoding conversion table that defines a plurality of encoding conversion schemes in the course of performing white-box encryption. The white-box encryption performing unit 320 may perform external encoding during the entire encryption process based on the encoding conversion table. In one embodiment, the white-box encryption performing unit 320 may generate the encoding conversion table, the XOR table and the alpha update table necessary for the subsequent encryption process in the process of performing white-box encryption. In one embodiment, the white-box encryption performing unit 320 may store in the memory a white-box table, an XOR table, and an alpha update table for the generated second encryption key 410b, It is possible to provide both ease of implementation and safety at the same time.

In one embodiment, the white-box encryption performing unit 320 may determine at least one encryption key for performing white-box encryption among the plurality of encryption keys 410 based on Equation (1) below. More specifically, the white-box encryption performing unit 320 can calculate the 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 Box encryption of the encryption key. For example, assuming that the following s is set to 0.3 by the user, the white-box cryptographic execution unit 320 may perform encryption and decryption on the two cryptographic keys first and second encryption keys 410a and 410b used in the XTS mode 3 and t = 4 and s = 0.3 with respect to the first encryption key 410a can be detected as 3 and 1, respectively. 1, t = 4, s = 0.3 for the second cryptographic key 410b can be determined to be c = 2.5 by computing c = To determine c = 0.83 to perform white-box encryption on the corresponding second encryption key 410b.

[Equation 1]

(Where, n represents the number of times the encryption key is used as an input seed for the block encryption in the entire encryption process, t represents the total number of times of use for the entire plurality of encryption keys 410, (Which is greater than 0 and less than 1, for example, 0.3)

The divided plain-speech receiving unit 330 can receive a plurality of divided plain texts. More specifically, the divided plain-text receiving unit 330 can receive data as an object of encryption with a plurality of divided plain texts, and at a later stage, generates a white-box-based ciphertext based on a plurality of divided plain texts . For example, the divided plain-text receiving unit 330 may receive a plurality of divided plain texts P ₁ , P ₂ , P ₃ . In one embodiment, the length of each of the plurality of split plains may be the same as the ciphertext.

The divided plain text receiving unit 330 may encode a plurality of divided plain texts received prior to the block cipher encryption and may provide an input to the divided cipher text generation unit 340 as a plurality of divided plain texts that are externally encoded. In one embodiment, the split plain-text receiving unit 330 may perform outer encoding on each of the plurality of divided plain texts based on the encoding conversion table. For example, the dividing plain-text receiving unit 330 receives a plurality of divided plain texts P ₁ , P _2, and P ₃ and generates a plurality of divided plain texts, such as an identification number 440, based on an encoding conversion table defining a plurality of encoding conversion schemes by doing the external encoding on P _1, P ₂ and P _3, respectively _{(F (P 1), F} (P 2), F (P 3)) of the divided plain text an outer encoding P ₁ ', P _2' and P ₃ 'can be output and reflected in the next operation.

In one embodiment, the divided plain-text receiving unit 330 may securely protect the encoding conversion table used in the external encoding process applied to the plain text and the cipher text by using obfuscation, The process of decoding the encoded ciphertext can be protected by obfuscation.

The divided cipher text generation unit 340 generates a plurality of divided ciphertexts by block ciphering the plurality of divided plain texts by reflecting the encrypted block cipher through the white box encryption on the rest of the plurality of cipher keys 410 .

In one embodiment, the divided cipher text generator 340 can operate a white-box cryptographic operation mode for multiple blocks based on a XEX-based tweaked-codebook mode with ciphertext stealing (XTS) mode, have. More specifically, the divided cipher text generation unit 340 receives the encrypted block cipher through the white-box encryption based on the common encryption key from the white-box cipher performing unit 320 and performs a block cipher encryption process 430 to 480).

In one embodiment, the divided cipher text generation unit 340 performs an XOR operation between the encrypted block cipher and each of a plurality of externally encoded divided plain texts, and provides a result of performing the corresponding operation as an input for performing block cipher encryption . For example, the partitioned cipher text generation unit 340 generates a partitioned cipher text P ₁ 'by encrypting the block cipher T ₁ ' through the white-box encryption through the second encryption key 410 b and the outer- XOR operation can be performed and the output result of the XOR operation can be provided as an input to the process of block cipher encryption using the first encryption key 410a as 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 divided cipher text generation unit 340 may perform block cipher encryption based on AES, DES, or LEA to generate each of a plurality of divided ciphertexts. For example, the divided cipher text generation unit 340 generates a divided cipher text based on the result output through the XOR operation such as the identification number 450a and the encryption result of the corresponding block cipher based on the LEA based on the block cipher technology using the first cipher key 410a by doing can output a C _1, and the encrypted blocks password via the white-box encrypted using the second encryption key (410b), such as identification numbers 470a T ₁ 'and divided by an XOR operation on the output C ₁ of the above cryptogram

Can be output. In one embodiment,

Means an XOR operation performed on the basis of an XOR table.

In one embodiment, the divided cipher text generation unit 340 may perform the a update operation on the encrypted block cipher based on the alpha update table to reflect the process of performing the block cipher encryption for the next block among the multiple blocks . For example, the divided cipher text generation unit 340 performs an alpha update primary operation on the encrypted block cipher T ₁ 'through white-box encryption through the second encryption key 410b as in the identification number 430a, (G (T ₂ ) = T ₂ ') is input to the next block, and in the process of performing the block cipher encryption for the next block, the result (G (T ₂ ) = T ₂ ') to provide the corresponding secondary performance result (G (T ₃ ) = T ₃ ') as input to the next block.

에 관한 외부 인코딩을 수행하여 외부 인코딩된 분할 암호문을 출력할 수 있다.In one embodiment, the divided cipher text generation unit 340 may perform an outer encoding on each of the plurality of divided ciphertexts based on an encoding conversion table that externally encodes a plurality of divided ciphertexts after block cipher encryption. For example, the divided cipher text generation unit 340 generates a divided cipher text

Lt; RTI ID = 0.0 > ciphered < / RTI > ciphertext.

The control unit 350 can control the entire operation of the white box cryptographic operation mode control apparatus 300 and includes an encryption key receiving unit 310, a white box encryption performing unit 320, a divided plain text receiving unit 330, Unit 340 can control the data flow. In one embodiment, the control unit 350 may be implemented as a central processing unit (CPU) of the white-box cryptographic operation mode control device 300.

FIG. 5 is a block diagram showing an embodiment of a process in which the white-box cryptographic operation mode control device shown in FIG. 3 generates a plurality of divided ciphertexts according to a security mode. The cryptographic operating mode control method that may include the following steps is computer executable.

5, the encryption key receiving unit 310 can receive a plurality of encryption keys (step S505). The white-box encryption performing unit 320 may perform white-box encryption on one of the plurality of encryption keys 410 in the first security mode (steps S510 to S530), and may encrypt the plurality of encryption keys 410) (steps S535 to S550).

In the first security mode, the white-box encryption performing unit 320 may encrypt the block encryption by performing white-box encryption on one of the plurality of encryption keys 410 (step S510). In one embodiment, the white-box encryption performing unit 320 sets the second encryption key 410b having the smallest encryption number among the first and second encryption keys 410 used in the XTS mode as a common encryption key, And perform white-box encryption on the encryption key 410b. The divided plain-text receiving unit 330 can receive a plurality of divided plain texts, and can externally encode based on the encoding conversion table to provide a plurality of externally-encoded divided plain texts as input to the divided encrypted text generating unit 340 S515). The divided cipher text generation unit 340 reflects the encrypted block cipher through the white-box encryption on the rest of the plurality of cipher keys 410 (step S520) A plurality of divided ciphertexts can be generated by performing block cipher encryption for the first block (step S525). The divided cipher text generation unit 340 may perform outer encoding on each of the plurality of divided ciphertexts based on the encoding conversion table after the block cipher encryption (step S530).

In the second security mode, the white-box encryption performing unit 320 may encrypt the block encryption by performing block encryption on one of the plurality of encryption keys 410 (step S535). In one embodiment, the white-box cryptographic implementation unit 320 may perform block cipher encryption on the one based on AES, DES or LEA. The divided plain-speech receiving unit 330 may receive a plurality of divided plain texts and generate a plurality of outer-encoded divided plain texts based on the encoding conversion table (step S540). The divided cipher text generation unit 340 may generate a plurality of divided cipher texts by performing block cipher encryption for multiple blocks (step S545). The divided cipher text generation unit 340 may perform outer encoding on each of the plurality of divided ciphertexts based on the encoding conversion table after the block cipher encryption (step S550).

In one embodiment, the white-box cryptographic operating mode control device 300 may further include a third security mode for performing white-box encryption on all of the plurality of cryptographic keys 410. [

In one embodiment, the white-box cryptographic operating mode control device 300 controls the operation mode of the white-box encryption for multiple blocks to ensure security through white-box encryption that is safe for white-box attacks, It is possible to minimize the memory problem requiring degradation and a lot of space.

In one embodiment, the white-box cryptographic operating mode control device 300 applies white-box encryption to encryption keys with lower ratios in the entire cryptographic process, thereby enhancing security and at the same time efficiently operating in terms of encryption speed and memory space Can be controlled.

In one embodiment, the white-box cryptographic operating mode control apparatus 300 may enhance the security rather than using a fixed encoding scheme by forming an encoding pool for alpha update operations and XOR operations applying various encodings

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims It can be understood that

300: White Box Cryptographic Operating Mode Control Device
310: encryption key receiving unit 320: white box encryption performing unit
330: Divide plain-text receiving unit 340:
350:

Claims (10)

(a) receiving a plurality of encryption keys associated with a multi-block cipher;
(b) performing white-box encryption on one of the plurality of encryption keys in a first security mode to encrypt a block cipher;
(c) receiving a plurality of split plaintexts; And
(d) reflecting the encrypted block cipher to the rest of the plurality of encryption keys and block cipher encryption of the plurality of split clear texts to generate a plurality of divided ciphertexts, Cryptographic operating mode control method.
2. The method of claim 1, wherein step (b)
And performing block encryption on one of the plurality of encryption keys in a second security mode.
2. The method of claim 1, wherein step (b)
And performing white-box encryption on one of the plurality of encryption keys having the smallest number of encryption (hereinafter referred to as a common encryption key).
2. The method of claim 1, wherein step (c)
And external encoding the received plurality of split plain texts prior to the block cipher encryption.
2. The method of claim 1, wherein step (d)
And external encoding the plurality of divided ciphertexts after the block cipher encryption. ≪ Desc / Clms Page number 19 >
6. The method of claim 4 or 5, wherein step (b)
Further comprising generating an encoding conversion table in which a plurality of encoding conversion methods are defined in the performing of the white-box encryption,
And performing outer encoding on each of the plurality of divided plain texts and divided ciphertexts based on the encoding conversion table in the steps (c) and (d).
7. The method of claim 6, wherein step (d)
And performing an XOR operation between the encrypted block cipher and each of the externally encoded plurality of divided plain texts to provide a result of performing the operation as an input for performing the block cipher encryption, Encryption method.
The method of claim 1, wherein step (a)
And receiving the two keys used in the XEX-based tweaked-codebook mode with ciphertext stealing mode with the plurality of encryption keys.
2. The method of claim 1, wherein step (b)
Performing white-box encryption based on a WB (White Box) -AES (Advanced Encryption Standard), WB-DES (Data Encryption Standard) or WB-LEA (Lightweight Encryption Algorithm) Possible white-box cryptographic operating mode control methods.
An encryption key receiver for receiving a plurality of encryption keys associated with a multi-block cipher;
A white box encryption unit for encrypting a block cipher by performing white box encryption on one of the plurality of encryption keys in a first security mode;
A divided plain text receiving unit for receiving a plurality of divided plain texts; And
And a divided cipher text generator for reflecting the encrypted block cipher to the rest of the plurality of encryption keys and generating a plurality of divided cipher texts by block cipher encryption of the plurality of divided plain texts, Device.

Images