KR101282653B1 - Data substitution encryption device and method - Google Patents

Abstract

PURPOSE: A data substitution encoding device and a method thereof are provided to convert plain text data into substitution data which reduces a size based on a predetermined substitution table when the plain text data which needs improved security is encoded and encode the substitution data, thereby strengthening security of data encoding. CONSTITUTION: A substitution table management unit (111) stores a substitution table that characters correspond to selected data codes which express the characters as selected bit strings. When plain text data is inputted, a selection unit (112) selects a data code corresponding to a character based on the substitution table. A data conversion unit (113) substitutes the characters for the data code and converts the plain text data into substitution data. An encoding unit (114) encodes the substitution data by using a selected encoding key. [Reference numerals] (111) Substitution table management unit; (112) Selection unit; (113) Data conversion unit; (114) Encoding unit; (115) Ratio calculation unit; (116) Grouping unit; (117) Data encoding unit; (118) Output data generation unit; (119) Multiple determination unit; (120) Coefficient calculation unit; (121) Data correction unit

Description

DATA SUBSTITUTION ENCRYPTION DEVICE AND METHOD}

Embodiments of the present invention are directed to techniques associated with encryption of plain text data that requires security, such as personal information.

Recently, with the widespread use of the Internet, more and more users are shopping through e-commerce sites or using web-based financial transactions such as Internet banking.

In general, users need to register as a member of a web site for security reasons in order to use such a web-based service.

In addition, in recent years, most web sites encourage users to join as members, so that only the subscribed members can use all the information or functions provided by the web site.

In general, a general web site collects personal information such as social security numbers of users at the time of membership registration. The collected personal information is often stored and managed in the personal information database of each site operator.

As a result, recently, hacking technologies such as keylogging, sniffing, phishing, and the like are increasingly being used to increase personal information and cause economic and social damage.

Accordingly, in order to prevent leakage of the personal information of members stored in the personal information database, the operator of each site often encrypts the personal information of the members by using various encryption techniques and stores the personal information in the personal information database.

In general, in order to encrypt and store data on a database, it is necessary to encode the data so as to match the storage standard of the database.

For example, if only data that has been subjected to base64 encoding on the database can be stored, the data to be stored in the database is 24 bits in that base64 encoding supports input data having a size of 24 bits. It should be changed to data having a size of.

Therefore, there is a need for a study on a data encryption technique that can efficiently store various security data on a database while preventing damage caused by personal information leakage.

Embodiments of the present invention, when encrypting the plain text data that requires security, such as personal information to be stored in a database, etc., converts the plain text data into the replacement data reduced in the size of the data using a predetermined substitution table and then converting By performing encryption and encoding on the replaced data, it is possible to further enhance security in data encryption.

In a data substitution encryption apparatus according to an embodiment of the present invention, a plurality of characters and a plurality of predetermined data codes representing each of the plurality of characters in a predetermined number of bit strings are recorded so as to correspond to each other. Substitution table management unit for storing and maintaining a table, when plain text data composed of at least one of the plurality of characters is input, referring to the substitution table, selecting at least one data code corresponding to each of the at least one character A selection unit to convert the data code for each of the at least one character into the selected at least one data code to convert the plain text data into replacement data comprising the selected at least one data code and the replacement data Encrypt using a selected encryption key and encrypt It includes a portion encoded for performing data encoding (encoding) for the replacement data.

In addition, the data substitution encryption method according to an embodiment of the present invention is a substitution table in which a plurality of characters and a plurality of predetermined data codes representing each of the plurality of characters represented by a predetermined number of bit strings are recorded so as to correspond to each other. Maintaining at least one of the plurality of characters, and selecting at least one data code corresponding to each of the at least one character by referring to the substitution table, when plain text data including at least one of the plurality of characters is input. Converting the data code for each character into the selected at least one data code, converting the plain text data into substitution data composed of the selected at least one data code, and converting the substitution data using a selected encryption key. Encrypt the data encoding for the encrypted replacement data. And a step of performing.

Embodiments of the present invention, when encrypting the plain text data that requires security, such as personal information to be stored in a database, etc., converts the plain text data into the replacement data reduced in the size of the data using a predetermined substitution table and then converting By performing encryption and encoding on the substituted data, security can be further enhanced in data encryption.

1 is a diagram showing the structure of a data substitution encryption apparatus according to an embodiment of the present invention.
2 is a view for explaining the operation of the data substitution encryption apparatus according to an embodiment of the present invention.
3 is another diagram for describing an operation of a data substitution encryption apparatus according to an embodiment of the present invention.
4 is a flowchart illustrating a data substitution encryption method according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

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

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram showing the structure of a data substitution encryption apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the data substitution encryption apparatus 110 according to an embodiment of the present invention includes a substitution table manager 111, a selector 112, a data converter 113, and an encoder 114. .

The substitution table management unit 111 stores and maintains a substitution table in which a plurality of characters and a plurality of predetermined data codes representing each of the plurality of characters in a predetermined number of bit strings correspond to each other. .

In this case, the selected number is a value smaller than the number of bit strings included in the data code for each of the at least one character, and the plurality of the plurality of selected characters are selected based on the number of the plurality of characters. A value selected to be represented by data codes.

In relation to this, the substitution table is described by way of example as follows.

In general, since characters such as alphabets and numbers are 8 bits of data, the number of bit strings included in the data code for the characters is eight.

However, considering only English letters and numbers, only 62 letters and numbers are used. Therefore, if only English letters and numbers are used as data, only English letters and numbers can be represented even if a data code having only 6 bit strings is used. Can be.

That is, in the case of using only English letters and numbers as data in a microprocessor-based computing device, it is sufficient to represent a character as a data code having a size of 6 bits rather than a data code having a size of 8 bits.

Thus, assuming that the data substitution encryption apparatus 110 supports only the characters corresponding to the alphabet and the number as the data to be encrypted, the user may have a value smaller than 8, which is the number of bit strings used to represent the original character data. Selects a value of '6', which is the number of bit strings capable of representing all 62 characters, and allocates a data code having a size of 6 bits represented by 6 bit strings to each of the 62 alphanumeric characters and the substitution table. It can be made, and through the substitution table management unit 111 may be stored and maintained in the substitution table.

In this regard, Table 1 below shows an example of the substitution table.

text Correspondence data code s 010100 o 010010 f 000100 t 110101 w 100000 a 010101 r 000011 e 001001 ... ...

When the plain text data including at least one of the plurality of characters is input, the selecting unit 112 selects at least one data code corresponding to each of the at least one character with reference to the substitution table.

The data converter 113 converts the data code for each of the at least one character into the selected at least one data code, and converts the plain text data into replacement data composed of the selected at least one data code.

For example, when the plain text data composed of the letters' sa 'is input to the data substitution encryption apparatus 110 and the substitution table is as shown in Table 1 above, the selection unit 112 refers to the substitution table and the' s '010100' may be selected as the data code for the character 'a', and '010101' may be selected as the data code for the character 'a'.

Then, the data conversion unit 113 replaces the data code '01110011' according to the ASCII code table for the letter 's' with '010100', and the data code according to the ASCII code table for the letter 'a'. '01100001' can be replaced with '010101' to convert plain text data '0111001101100001' composed of the letters 'sa' into substitution data composed of '010100010101'.

An encoding unit 114 encrypts the replacement data using a predetermined encryption key and performs data encoding on the encrypted replacement data.

In this case, according to an embodiment of the present invention, the data substitution encryption apparatus 110 may further include a ratio calculator 115.

The ratio calculator 115 checks the size value of the input data supported by the data encoding and calculates a ratio of the size value of the input data to the size value of one data code represented by the predetermined number of bit strings.

In this case, according to an embodiment of the present invention, the encoding unit 114 may include a grouping unit 116, a data encoding unit 117, and an output data generation unit 118.

The grouping unit 116 groups the at least one data code constituting the substitution data by the number corresponding to the calculated ratio and at least one having a data size that matches the magnitude value of the input data. It can be divided into replacement data groups.

The data encoding unit 117 performs encryption on each of the at least one replacement data group by using the selected encryption key, and performs data encoding on each of the at least one replacement data group on which the encryption has been performed. .

The output data generator 118 merges the at least one replacement data group on which the data encoding is performed into one data to generate output data.

Hereinafter, an operation of the data substitution encryption apparatus 110 according to an embodiment of the present invention will be described in detail with reference to FIG. 2.

First, it is assumed that the substitution table manager 111 stores a substitution table in which a plurality of selected data codes expressed in six bit strings corresponding to English characters are stored, as shown in Table 1 above. Suppose we do base64 encoding on the input data.

When the plain text data composed of the letters 'software' is input to the data substitution encrypting apparatus 110, the selection unit 112 refers to the substitution table and refers to the 'software' included in the plain text data. Eight data codes corresponding to each character 'can be selected.

In this case, the selector 112 may select '010100' 221 for the letter 's', select '010010' 222 for the letter 'o', and select the letter 'f'. '000100' (223) for 't', '110101 (224) for' t ',' 100000 '(225) for' w ',' a ' You can select '010101' (226) for the letter ',' '000011' (227) for the letter 'r', and '001001' (228) for the letter 'e'. .

Then, the data conversion unit 113 may convert the plain text data into the replacement data composed of the selected eight data codes by replacing the data codes for each character of 'software' with the selected eight data codes.

In this case, the ratio calculator 115 may check the size value of the input data supported by the base64 encoding, and calculate a ratio of the size value of the input data to the size value of one data code represented by six bit strings. Can be.

base64 encoding is an encoding method that receives 3 characters in 8-bit units as input and obtains 4 characters in 6-bit units as output. It basically supports 24 bits of input data.

Therefore, the ratio calculating unit 115 has a size value of 6 bits of one data code represented by six bit strings and a size value of the input data supported by base64 encoding is 24 bits. The ratio of the size value of the input data supported by base64 encoding may be calculated as '4'.

As such, when the calculation for the ratio is completed, the grouping unit 116 displays the eight data codes constituting the substitution data as four numbers corresponding to the calculated ratio, as shown by reference numerals 231 and 232. The replacement data may be divided into a replacement data group 1 231 and a replacement data group 2 232 having a data size that matches a 24-bit size value of input data supported by base64 encoding.

Then, as shown at 240, the data encoding unit 117 may perform encryption using an encryption key selected for each of the substitution data group 1 231 and the substitution data group 2 232. In addition, base64 encoding may be performed on each of the substitution data group 1 231 and the substitution data group 2 232 on which the encryption is performed.

As shown by reference numeral 240, the output data generator 118 merges the substitution data group 1 231 and the substitution data group 2 232 on which the base64 encoding is performed into one data, and the reference numeral 250. The final output data called 'mhk4r3bn' may be generated as shown in FIG.

As a result, the data substitution encryption apparatus 110 according to an embodiment of the present invention encrypts plain text data requiring security such as personal information to be stored in a database or the like, and converts the plain text data using a predetermined substitution table. By converting to the replacement data having a reduced size and then encrypting and encoding the converted replacement data, security in data encryption can be further enhanced.

In addition, in the case of data encryption, when an encoding method such as base64 encoding is used, the base64 encoding method is an encoding method that receives 3 characters in 8-bit units as inputs and obtains 4 characters in 6-bit units as outputs. If the number of characters included in the output data is increased from the number of characters included in the plain text data, or if the 32-bit sized plain text data consisting of four characters is input, the padding character is generated through the base64 encoding process. In addition, the size of the output data may be increased than that of the input data in that output data having a total size of 48 bits consisting of eight characters in units of 6 bits may be obtained.

As such, when the size of the output data increases or the number of characters increases, management of the database may be difficult in that the capacity or format of the database in which the output data is to be stored may be limited.

However, the data substitution encryption apparatus 110 according to an embodiment of the present invention replaces the data code for the four characters with a data code of 6 bits even when 32-bit plain text data composed of four characters is input. Since the size of the plain text data can be reduced to 24 bits, when base64 encoding is performed on the replacement data reduced to the size of 24 bits, output data consisting of 4 characters having a size of 24 bits is obtained. Therefore, unlike the existing encryption method, even when using base64 encoding, the size of the output data does not increase, and the number of characters included in the output data may not increase.

The operation of the data substitution encryption apparatus 110 according to an embodiment of the present invention has been described above in detail with reference to FIG. 2. Hereinafter, the structure of the data substitution encryption apparatus 110 will be described with reference to FIG. 1.

According to an embodiment of the present invention, the data substitution encryption apparatus 110 may further include a multiple determination unit 119, a number calculation unit 120, and a data correction unit 121.

When the plain text data composed of the at least one character is input, the multiplication determining unit 119 determines whether the number of the at least one character constituting the plain text data corresponds to a multiple of a value corresponding to the calculated ratio. do.

When it is determined that the number of the at least one character does not correspond to a multiple of a value corresponding to the calculated ratio, the number calculator 120 calculates the calculated plaintext data based on the number of the at least one character. Computes the minimum number of characters that must be added to contain a character by a multiple of the value corresponding to the ratio.

The data corrector 121 selects the minimum number of padding characters from the plurality of characters and corrects the plain text data by adding the padding characters to the plain text data.

In this case, the selector 112 may select the at least one data code based on the plain text data on which the correction is completed.

Hereinafter, with reference to FIG. 3, the operation of the multiple determination unit 119, the number calculating unit 120, and the data correcting unit 121 will be described in detail.

First, it is assumed that the substitution table manager 111 stores a substitution table in which a plurality of selected data codes expressed in six bit strings corresponding to English characters are stored, as shown in Table 1 above. Suppose we do base64 encoding on the input data.

In addition, as in the embodiment described with reference to FIG. 2, the ratio calculator 115 has a size value of 6 bits of one data code represented by six bit strings, and the size value of the input data supported by base64 encoding. Since this is 24 bits, it is assumed that a ratio of the size value of the data code to the size value of the input data supported by base64 encoding is calculated as '4'.

At this time, when the plain text data composed of the letters 'softw' is input to the data substitution encrypting apparatus 110, the multiple determination unit 119 determines that the number of characters constituting the plain text data is equal to the number. It may be determined whether it corresponds to a multiple of the calculated ratio '4'.

In this regard, base64 encoding is an encoding scheme that supports input data of 24 bits, and the permutation table is a multiple of 4 in that the permutation table is a table that supports substituting 8-bit data codes with 6-bit data codes. Only when plain text data consisting of a number of characters is input, the replacement data may be divided into four groups of 24-bit data groups to match the size of the input data supported by base64 encoding, so the multiple determination unit 119 may determine the above. It may be determined whether the number of characters constituting the plain text data corresponds to a multiple of the calculated ratio '4'.

In the present embodiment, since the number of characters included in the plain text data is only five and does not correspond to a multiple of four, the number calculating unit 120 needs to be added so that the number of characters to be included in the plain text data is a multiple of four. You can calculate the minimum number of characters to do.

In the present embodiment, since the number of characters included in the plain text data is five, the minimum number of characters to be added in order for the number of characters to be included in the plain text data to be a multiple of four is three. Accordingly, the number calculator 120 may calculate the minimum number of characters as 'three'.

Then, the data correction unit 121 may correct the plain text data by selecting three padding characters among the alphabet characters registered in the substitution table and then adding the padding characters to the plain text data.

In relation to this, the data correction unit 121 selects three padding characters 'a' and adds three padding characters 'a' to the plain text data composed of 'softw' as shown at 320. You can generate corrected plain text data called 'softwaaa'.

Then, the selecting unit 112 may select eight data codes corresponding to each of the letters 'softwaaa' included in the corrected plain text data with reference to the substitution table.

In this case, the selector 112 may select '010100' 331 for the letter 's', select '010010' 332 for the letter 'o', and select the letter 'f'. '000100' (333) for 't', '110101 (334) for' t ',' 100000 '(335) for' w ',' a ' '010101' (336) can be selected for the letter 'a', '010101' (337) can be selected for the letter 'a', and '010101' (338) can be selected for the letter 'a'. .

The data conversion unit 113 may convert the corrected plain text data into replacement data composed of the selected eight data codes by substituting the selected eight data codes for the data codes for each character of 'softwaaa'. .

At this time, the grouping unit 116 replaces the eight data codes constituting the replacement data by grouping four data codes corresponding to the ratio calculated by the ratio calculating unit 115, as shown at 341 and 342. Data may be divided into Substitution Data Group 1 341 and Substitution Data Group 2 342 having a data size that matches a 24-bit size value of input data supported by base64 encoding.

Then, the data encoding unit 117 may perform encryption using the encryption key selected for each of the substitution data group 1 341 and the substitution data group 2 342, as shown at 350. In addition, base64 encoding may be performed on each of the substitution data group 1 341 and the substitution data group 2 342 on which the encryption is performed.

As shown by reference numeral 350, the output data generator 118 merges the substitution data group 1 341 and the substitution data group 2 342 in which the base64 encoding is performed into one data and 360. The final output data called 'grTw28Eb' as shown in FIG.

4 is a flowchart illustrating a data substitution encryption method according to an embodiment of the present invention.

In step S410, a plurality of characters and a plurality of predetermined data codes representing each of the plurality of characters in a predetermined number of bit strings are maintained to correspond to each other.

In this case, according to an embodiment of the present invention, the predetermined number is a value smaller than the number of bit strings included in the data code for each of the at least one character, and the plurality of the plurality of characters is based on the number of the plurality of characters. It may be a predetermined value so that all of the characters can be represented by the plurality of predetermined data codes.

In operation S420, when plain text data including at least one of the plurality of characters is input, at least one data code corresponding to each of the at least one character is selected with reference to the substitution table.

In step S430, the data code for each of the at least one character is replaced with the selected at least one data code to convert the plain text data into replacement data composed of the selected at least one data code.

In step S440, the replacement data is encrypted using the selected encryption key, and data encoding is performed on the encrypted replacement data.

At this time, according to an embodiment of the present invention, the data substitution encryption method is a data code 1 represented by the predetermined number of bit strings after checking the size value of the input data supported by the data encoding after step (S410) The method may further include calculating a ratio of the size value of the input data to the size value of the dog.

In this case, in step S440, the at least one data code constituting the replacement data is grouped by the number corresponding to the calculated ratio, and the replacement data is at least one having a data size matching the size value of the input data. Dividing into at least one substituting data group, performing encryption using the selected encryption key for each of the at least one substituting data group, and performing the data encoding on each of the at least one substituting data group on which the encryption is performed. And performing at least one substitution data group on which the data encoding is performed into one data to generate output data.

Further, according to an embodiment of the present invention, in the data substitution encryption method, if plain text data composed of the at least one character is input before step S420, the number of the at least one character constituting the plain text data is increased. Determining whether it corresponds to a multiple of the value corresponding to the calculated ratio, and if it is determined that the number of the at least one character does not correspond to a multiple of the value corresponding to the calculated ratio, the at least one Calculating a minimum number of characters to be added in order to include the characters in the plain text data by a multiple of a value corresponding to the calculated ratio based on the number of characters and the calculated minimum number of characters among the plurality of characters. Select a padding character to correct the plaintext data by adding the padding character to the plaintext data. It may further comprise the step.

In this case, in step S420, the at least one data code may be selected based on the plain text data on which the correction is completed.

The data substitution encryption method according to an embodiment of the present invention has been described above with reference to FIG. 4. Here, since the data substitution encryption method according to an embodiment of the present invention may correspond to the configuration of the operation of the data substitution encryption apparatus 110 described with reference to FIGS. 1 to 3, a detailed description thereof will be omitted. Shall be.

Data substitution encryption method according to an embodiment of the present invention is implemented in the form of program instructions that can be executed by various computer means may be recorded in a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

As described above, the present invention has been described by specific embodiments such as specific components and the like. For those skilled in the art, various modifications and variations are possible from these descriptions.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

110: data substitution encryption device
111: substitution table management unit 112: selection unit
113: data conversion section 114: encoding section
115: ratio calculator 116: grouping unit
117: data encoding unit 118: output data generation unit
119: drainage determination unit 120: number calculation unit
121: data correction unit

Claims (9)

A substitution table management unit which stores and maintains a substitution table in which a plurality of characters and a plurality of predetermined data codes representing each of the plurality of characters in a predetermined number of bit strings correspond to each other;
A selection unit for selecting at least one data code corresponding to each of the at least one character by referring to the substitution table when plain text data including at least one character among the plurality of characters is input;
A data converter for converting the data code for each of the at least one character into the selected at least one data code and converting the plain text data into replacement data composed of the selected at least one data code; And
An encoding unit for encrypting the substitution data using a predetermined encryption key and performing data encoding on the encrypted substitution data
Lt; / RTI >
The selected number is
The value is smaller than the number of bit strings included in the data code for each of the at least one character, and all of the plurality of characters may be represented by the plurality of predetermined data codes based on the number of the plurality of characters. A data substitution encryption device that is a predetermined value. delete The method of claim 1,
A ratio calculator for checking a size value of the input data supported by the data encoding and calculating a ratio of the size value of the input data to the size value of one data code represented by the predetermined number of bit strings;
Further comprising:
The encoding unit
At least one replacement data group having a data size that matches the size value of the input data by grouping the at least one data code constituting the replacement data by the number corresponding to the calculated ratio Grouping unit to divide into;
A data encoding unit performing encryption on each of the at least one replacement data group using the selected encryption key, and performing data encoding on each of the at least one replacement data group on which the encryption is performed; And
An output data generation unit for generating output data by merging at least one substitution data group on which the data encoding is performed into one data;
Data substitution encryption device comprising a. The method of claim 3,
A multiplier determination unit determining whether the number of the at least one character constituting the plain text data corresponds to a multiple of a value corresponding to the calculated ratio when the plain text data including the at least one character is input;
If it is determined that the number of the at least one character does not correspond to a multiple of the value corresponding to the calculated ratio, the value of the value corresponding to the calculated ratio in the plain text data based on the number of the at least one character A number calculating unit that calculates a minimum number of characters to be added in order to include characters by multiples; And
A data correction unit for correcting the plain text data by selecting the padding character from the plurality of characters and adding the padding character to the plain text data
Further comprising:
The selection unit
And selecting the at least one data code based on the corrected plain text data. Maintaining a substitution table in which a plurality of characters and a plurality of predetermined data codes representing each of the plurality of characters in a predetermined number of bit strings correspond to each other;
Selecting at least one data code corresponding to each of the at least one character by referring to the substitution table when plain text data composed of at least one of the plurality of characters is input;
Replacing the data code for each of the at least one character with the selected at least one data code to convert the plain text data into replacement data consisting of the selected at least one data code; And
Encrypting the substitution data using a predetermined encryption key and performing data encoding on the encrypted substitution data
Lt; / RTI >
The selected number is
The value is smaller than the number of bit strings included in the data code for each of the at least one character. A data substitution encryption method that is a predetermined value. delete The method of claim 5,
Checking a size value of the input data supported by the data encoding and calculating a ratio of the size value of the input data to the size value of one data code represented by the predetermined number of bit strings;
Further comprising:
Performing the data encoding is
At least one replacement data group having a data size that matches the size value of the input data by grouping the at least one data code constituting the replacement data by the number corresponding to the calculated ratio Dividing into;
Performing encryption using the selected encryption key on each of the at least one replacement data group, and performing data encoding on each of the at least one replacement data group on which the encryption is performed; And
Generating output data by merging the at least one substitution data group on which the data encoding is performed into one data;
Data substitution encryption method comprising a. The method of claim 7, wherein
When plain text data consisting of the at least one character is input, determining whether the number of the at least one character constituting the plain text data corresponds to a multiple of a value corresponding to the calculated ratio;
If it is determined that the number of the at least one character does not correspond to a multiple of the value corresponding to the calculated ratio, the value of the value corresponding to the calculated ratio in the plain text data based on the number of the at least one character Calculating a minimum number of characters to be added in order for the characters to be included in multiples; And
Correcting the plain text data by selecting the minimum number of padding characters from the plurality of characters and then adding the padding characters to the plain text data;
Further comprising:
Selecting the at least one data code
And selecting the at least one data code based on the corrected plain text data. A computer-readable recording medium having recorded thereon a program for performing the method of any one of claims 5 or 7-8.

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