KR100531577B1 - Device for coding/decoding document - Google Patents

Abstract

The present invention relates to an encryption method for providing security of a document, and in particular, by setting the order of the round keys used in the Rijndael encryption method according to the secret key provided to the user, the document encryption can be further improved. A document encryption / decryption apparatus.

The document encryption / decryption apparatus according to the present invention performs an initial round and N rounds, and applies to a document encryption / decryption apparatus of the Rijndael encryption method to perform document encryption and decryption processing by applying a predetermined round key. The encryption / decryption apparatus performs document encryption and decryption processing by sequentially applying N + 1 round keys composed of a secret key and an N round key for the initial round and N rounds, but a secret assigned to the corresponding device. Characterized in that it is applied sequentially from the round key corresponding to the key information.

Description

Device for coding / decoding document

The present invention relates to an encryption method for providing security of a document, and in particular, by setting the order of the round keys used in the Rijndael encryption method according to the secret key provided to the user, the document encryption can be further improved. A document encryption / decryption apparatus.

Conventional encryption methods include the DES encryption method adopted as an international standard method in 1997. The DES encryption method belongs to a repetitive block encryption system. The DES encryption method is used to increase the degree of security by appropriately using a weak cryptographic function.

However, with the rise of computer computing power, NIST decided to use Rijndael encryption method in October 2000 as the Advanced Encryption Standard (AES).

The Rijndael encryption method was developed in consideration of security against attack, processing speed, simplicity of code, and simplicity of design in various types of platforms. In addition, it takes about 148 trillion years for the current computer to decrypt the code, and 30 years for the quantum computer called the dream computer.

  Rijndael encryption method is based on the non-Feistel structure and consists of three independent round transformations. The encryption process of the Rijndael encryption method consists of an initial round, a repeat round, and a final round as shown in FIG. 1, and the initial round performs an exclusive or XOR operation on the secret key and the original text. Byte Sub), RowShift (ShiftRow), Column Synthesis (MixClumn), and RoundKey Synthesis (AddRoundKey) are repeated a predetermined number of times. ) And finally the ciphertext is outputted.

In general, the Rijndael encryption method performs nine repetitive rounds for encrypting an original text, and performs one final round. That is, a total of 10 rounds are performed, and the round key applied to each round is fixed as shown in Table 1.

Round0 Round1 Round2 Round3 Round4 Round5 Round6 Round7 Round8 Round9 RK0 RK1 RK2 RK3 RK4 RK5 RK6 RK7 RK8 RK9

Here, Round0 to Round9 represent a total of 10 round repetitions, and RK0 to RK9 represent a round key synthesized in each round key synthesis step.

Therefore, given the current technology that is developing day by day, the round key is applied in the same order to all documents, indicating the vulnerability of document encryption attack.

Accordingly, the present invention has been made in view of the above circumstances, and provides a document encryption / decryption apparatus capable of increasing the degree of ciphertext by setting the round key application order of the Rijndael encryption method according to the secret key provided to the user. Its technical purpose is.

In the document encryption / decryption apparatus according to the present invention for achieving the above object, the Rijndael encryption method is to perform the initial round and N rounds, and to perform document encryption and decryption processing by applying a predetermined round key when performing the round. In the document encryption / decryption apparatus, the encryption / decryption apparatus performs document encryption and decryption processing by sequentially applying N + 1 round keys composed of a secret key and N round keys for the initial round and N rounds. Characterized in that it is applied sequentially from the round key corresponding to the secret key information assigned to the device.

That is, according to the above, while maintaining the basic structure of the Rijndael encryption method, the application of the round key can be changed according to the secret key provided to the user, thereby increasing the secretion rate.

Hereinafter will be described an embodiment according to the present invention.

Figure 2 is a block diagram showing the functional separation of the internal structure of the document encryption / decryption apparatus according to the present invention, which illustrates the case where the document encryption / decryption apparatus is formed of a device for performing PCI communication, that is, a PCI card in particular It is.

As shown in FIG. 2, the document encryption / decryption apparatus according to the present invention includes a predetermined controller 10 coupled to the memory 30 through the PCI interface 20, and an encryption / decryption unit to be described later. And a round key sequence generation unit 40 for providing predetermined round key selection information, and an encryption / decryption unit 50 for encrypting and decrypting a predetermined document.

Here, the encryption / decryption unit 50 performs document encryption processing and decryption processing according to the Rijndael encryption method as shown in FIG. 1, and the control unit 10 controls the user's secret to the round key sequence generation unit 40. The key information is controlled to provide the encryption / decoding unit 50 with round key address information for selecting the round key used in the encryption / decoding unit 50. The encryption / decryption unit 50 reads sequentially from the round key corresponding to the round address applied from the round key order generation unit 40, and uses the same for encryption and decryption.

In addition, the memory 30 is for storing a document to be encrypted and decrypted and an encrypted and decrypted document.

3 is a block diagram illustrating a functional separation of the internal configuration of the round key sequence generation unit 40 shown in FIG.

As shown in FIG. 3, the round key order generation unit 40 may include, for example, a first modular operation unit 41 for generating a remainder obtained by dividing a 4-bit secret key by 11, which is applied from the control unit 10, and the control unit 10. Counter 42, which is incremented by "1" from 0 to 10 or decreased by "1" from 10 to 0, based on the control signal from the control unit, is output from 4-bit data, and applied from the first modular operation unit 41. Adder 43 for adding and processing 4-bit data to be applied from the counter 42 and round-bit address information that is the remainder obtained by dividing the 5-bit data applied from the adder 43 by 11; It is configured to include a second modular operation unit 44 to generate.

At this time, the counter 42 performs a count of incrementing by "1" from 0 to 10 in the case of a control signal for encryption processing from the control unit 10, and from "10 to 0" in the case of a control signal for decryption processing. Configured to perform a decrement by "".

In addition, the secret key is information set in a user terminal such as a computer on which the present encryption / decryption apparatus is installed. As described in the application number 10-2002-0010125 filed on February 26, 2002 by the present applicant, It can be provided from the document security device through. In addition, the secret key may be fixedly set in the encryption / decryption apparatus or may be arbitrarily set by a computer user.

In addition, the first and second modular operation units 41 and 44 are set to a number that divides the "total number of rounds + 1" in the Rijndael encryption method. In general, the total number of rounds of the Rijndael encryption method is 10. In the first embodiment, the dividing number of the first and second modular operation units 41 and 44 is "11". In addition, the counter 42 is also configured to count the same number of times as "total rounds + 1" performed during encryption.

On the other hand, Figure 4 is a block diagram showing the functional separation of the internal configuration of the encryption / decryption unit 50 shown in FIG.

As shown in FIG. 4, the encryption / decryption unit 50 has a predetermined round key table in which a starting round key (including a secret key) for each round key address information provided from the round key order generation unit 40 is set differently. And a round key information providing unit 51 for sequentially outputting a round key starting from a round key corresponding to the round key address information. That is, the round key providing order output from the round key information providing unit 51 is changed according to the secret key information. Table 2 shows the round key providing order according to the secret key.

Rain wheat key Early round Repeat round Final round Early round Round0 Round1 Round2 Round3 Round4 Round5 Round6 Round7 Round8 Round9 0000 Secret key Rk0 Rk1 Rk2 Rk3 Rk4 Rk5 Rk6 Rk7 Rk8 Rk9 0001 Rk0 Rk1 Rk2 Rk3 Rk4 Rk5 Rk6 Rk7 Rk8 Rk9 Secret key 0010 Rk1 Rk2 Rk3 Rk4 Rk5 Rk6 Rk7 Rk8 Rk9 Secret key Rk0 0011 Rk2 Rk3 Rk4 Rk5 Rk6 Rk7 Rk8 Rk9 Secret key Rk0 Rk1 1001 Rk3 Rk4 Rk5 Rk6 Rk7 Rk8 Rk9 Secret key Rk0 Rk1 Rk2 0101 Rk4 Rk5 Rk6 Rk7 Rk8 Rk9 Secret key Rk0 Rk1 Rk2 Rk3 0110 Rk5 Rk6 Rk7 Rk8 Rk9 Secret key Rk0 Rk1 Rk2 Rk3 Rk4 0111 Rk6 Rk7 Rk8 Rk9 Secret key Rk0 Rk1 Rk2 Rk3 Rk4 Rk5 1000 Rk7 Rk8 Rk9 Secret key Rk0 Rk1 Rk2 Rk3 Rk4 Rk5 Rk6 1001 Rk8 Rk9 Secret key Rk0 Rk1 Rk2 Rk3 Rk4 Rk5 Rk6 Rk7 1010 Rk9 Secret key Rk0 Rk1 Rk2 Rk3 Rk4 Rk5 Rk6 Rk7 Rk8 1011 Secret key Rk0 Rk1 Rk2 Rk3 Rk4 Rk5 Rk6 Rk7 Rk8 Rk9 1100 Rk0 Rk1 Rk2 Rk3 Rk4 Rk5 Rk6 Rk7 Rk8 Rk9 Secret key 1101 Rk1 Rk2 Rk3 Rk4 Rk5 Rk6 Rk7 Rk8 Rk9 Secret key Rk0 1110 Rk2 Rk3 Rk4 Rk5 Rk6 Rk7 Rk8 Rk9 Secret key Rk0 Rk1 1111 Rk3 Rk4 Rk5 Rk6 Rk7 Rk8 Rk9 Secret key Rk0 Rk1 Rk2

 That is, as shown in Table 2, the round key starting order is changed for the secret key information.

In addition, as shown in FIG. 4, the encryption / decoding unit 50 is a first multiplexer for selectively outputting the original document data of 128 bits and the document data fed back from the second multiplexer 57 to be described later. 52, the flip-flop 53 for temporarily storing the 128-bit document data output from the first multiplexer 52, the 128-bit document data output through the flip-flop 53, and the round key information providing unit 51. A round key synthesis unit 54 for performing an XOR operation on the 128-bit round key applied from the X-axis, and an encryption processing unit 55 for encrypting document data applied from the round key synthesis unit 54; A decryption processor 56 for decrypting document data applied from the round key synthesis unit 54 and the first multiplexer 52 for selectively applying document data applied from the encryption processor 55 or the decryption processor 56. It is configured to include a second multiplexer (57) for providing a feedback input.

In addition, the encryption processing unit 55 performs the data replacement (ByteSub: ST2, ST6), row shift (ShiftRow: ST3, ST7), and column synthesis (MixColumn: ST4) processes of the repeated round and the final round of FIG. In order to do so, the data output unit 551, the row shift unit 552, the column synthesizer 553, the data output from the row shift unit 552 and the data output from the column synthesis unit 553 It is configured to include a third multiplexer 554 for selectively outputting according to the predetermined control signal (Ctrl3).

Here, the data replacing unit 551 performs an operation of replacing the input a _ij data with b _ij data according to a predetermined rule (S-box) as shown in FIG.

As illustrated in FIG. 5B, the row shift unit 552 shifts the rows of the replacement data output from the data replacing unit 551 to the left by a shift offset. For example, the second row data _{"B 10, B 11, B} 12, B 13" combination is shifted to _{"B 11, B 12, B} 13, B 10" data.

In addition, as illustrated in FIG. 5C, the column synthesis unit 553 performs arithmetic processing on each column data of data output from the row shift unit 552 with a predetermined polynomial c (x).

Meanwhile, in FIG. 4, the decryption processor 56 is an inverse transform process performed by the encryption processor 55 to perform inverse thermal synthesis on data applied from the round key synthesis unit 54. For selectively outputting the thermal synthesis processing unit 561, the data applied from the round key synthesis unit 54, and the data applied from the inverse thermal synthesis processing unit 561 according to a predetermined control signal Ctrl4. From the fourth multiplexer 562, an inverse row shift processing unit 63 for inverse row shifting the data output from the fourth multiplexer 562, and an inverse row shifting unit 63. And an inverse data substitution unit 564 for inverse data substitution processing of the output data.

That is, the inverse thermal synthesis unit 561 performs an inverse transform process on the thermal synthesis unit 553 as shown in FIG. 5C, and the inverse row shift processing unit 563 is illustrated in FIG. 5. Inverse transformation processing is performed on the row shift processing unit 552 as shown in (B) of FIG. 5, and the inverse data replacing unit 564 performs inverse transformation processing on the data replacing unit 551 as shown in FIG. 5A. It is configured to perform, which is performed by using the inverse transform function of the encryption function, the detailed description thereof will be omitted.

Next, the operation of the encryption / decryption device having the above-described configuration will be described.

First, the controller 10 provides the secret key information provided to the user terminal in which the present encryption / decryption apparatus is installed to the round key order generation unit 40 to provide a round key address corresponding to the secret key information to the encryption / decryption unit 50. To be provided).

In addition, the controller 10 receives document data to be encrypted and decrypted from the memory 30 and divides the document data into predetermined size units, for example, 128 bits, and sends the document data to the encryption / decryption unit 50.

In the above state, the controller 10 performs a round operation according to the encryption / decoding based on a clock signal provided from a clock providing unit (not shown) that provides an operation clock of the encryption / decoding device.

1. The encryption operation of the encryption / decryption apparatus according to the present invention is as follows.

The control unit 10 controls the first to third multiplexers of the encryption / decryption apparatus as shown in FIG. 6 (X) during the encryption operation.

First, the second control signal Ctrl 2 having a low level (“0”) is provided to the second multiplexer 57 to control the output signal of the encryption unit 55 to be fed back to the first multiplexer 51.

In the above state, the controller 10 provides the first multiplexer 52 with the first control signal Ctrl 1 having a low level (“0”) during the first clock period so that the original document data is flip-flop 53. Will be output as At this time, the controller 10 provides the first control signal Ctrl1 so that the rising edge section of the first clock becomes the center of the low level ("0") section as shown in FIG. 6 (X). In the rising edge state of the clock, 128 bits of document data are provided to the flip-flop 53.

Then, the data output from the flip-flop 53 is processed by the round key synthesizer 54 and the round key provided by the round key information providing unit 51 (the initial round of Table 2) and the exclusive oral (XOR). Is output. At this time, the control unit 10 is to provide a third control signal (Ctrl 3) of the low level ("0") to the third multiplexer 554, the output data of the round key synthesis unit 54 is data replacement The second multiplexer 57 is applied to the second multiplexer 57 through the unit 551, the row shift unit 552, and the column synthesizer 553, and the second multiplexer 57 receives data output from the column synthesizer 553. It is applied to the input of the multiplexer 52.

That is, during the first clock period, the first data substitution (ST2), the row shift (ST3), and the column synthesis (ST4) of the initial round process and the repeat round process are performed.

Subsequently, the control unit 10 provides the first multiplexer 52 with the first control signal Ctrl 2 having a high level (“1”) to the first multiplexer 52 when the second clock cycle is reached. The finished document data is controlled to be provided to the flip-flop 53. At this time, the second to fourth control signals Ctrl 2 to Ctrl 4 maintain the previous state and control to maintain the second clock cycle state until the ninth clock period.

That is, the repetitive rounding process of data replacement, row shift, column synthesis, and round key synthesis is performed on the document data processed by the initial rounding process for the second to ninth clock periods. At this time, the round key synthesis performs an XOR processing of the data fed back to the first multiplexer 52 and the round keys provided from the round key providing unit 51 (Round 0 to Round 7 in Table 2).

When the tenth clock cycle is reached, the round key synthesizing unit 54 extracts the round key (Round8 of Table 2) provided from the round key providing unit 51 to perform the round key synthesis ST5 of the last repetitive round process. It is treated with XOR. In addition, the controller 10 provides the third multiplexer 554 with a third control signal Ctrl3 having a high level (“1”) to perform data substitution ST6 and row shift ST7 during the final round process. do.

Finally, when the eleventh clock period is reached, the round key providing unit 51 provides the final round key (Round9 in Table 2) to the round key combining unit 54, and the document data being encrypted by the round key combining unit 54. The final round key is XORed to generate a cipher text for the document.

2. The decoding operation of the encryption / decryption apparatus according to the present invention is as follows.

The control unit 10 controls the first to fourth multiplexers of the encryption / decoding apparatus as shown in FIG. 6 (Y) during the decoding operation.

First, the second control signal Ctrl 2 having a high level (“1”) is provided to the second multiplexer 57 to control the output signal of the decoding processor 56 to be fed back to the first multiplexer 51.

In the above state, the controller 10 reads the cipher text data stored in the memory 30 and reads the data in a predetermined size, for example, in 128-bit units. At this time, the controller 10 provides the first control signal Ctrl 1 having a low level (“0”) to the first multiplexer 52 during the first clock period so that the document data of the ciphertext is transmitted through the flip-flop 53. It is provided to the round key synthesizing unit 54 to control the final round key (Round 9 in Table 2) and the exclusive ores (XOR). At this time, the controller 10 provides the first control signal Ctrl1 so that the rising edge section of the first clock is the center of the high level ("0") section as shown in FIG. 6 (Y). The 128-bit encrypted document data is provided to the flip-flop 53 in the rising edge state of the clock.

The controller 10 transmits the fourth control signal Ctrl 4 having a high level (“1”) to the fourth multiplexer 562 to transmit a signal output from the round key synthesis unit 54 to an inverse row shift unit. The control unit 543 and the inverse data replacing unit 564 output the second multiplexer 57.

That is, the controller 10 controls to start from the last round process when decrypting the ciphertext data stored in the memory 30. Therefore, the final round process is performed during the first clock period.

Thereafter, the controller 10 transmits the first control signal Ctrl 1 having the high level (“1”) to the first multiplexer 52 so that the feedback data applied from the second multiplexer 57 is flip-flop 53. It is controlled to be applied to the round key synthesis unit 54 through. In addition, the controller 10 transmits the fourth control signal Ctrl 4 having a low level (“0”) to the fourth multiplexer 562 so that the output data of the round key combining unit 54 is inversely thermally synthesized. It is controlled to be applied to the inverse row shift unit 562 through the unit 561. The data applied to the inverse row shift unit 562 is provided as an input of the first multiplexer 52 through the inverse data replacing unit 564 and the second multiplexer 57. That is, the decoding process according to the repetitive round operation is performed from the second clock period to the tenth clock period. The decoded data applied from the second multiplexer 57 to the first multiplexer 52 at the end of the tenth clock period is transmitted through the round synthesizer 54 in the eleventh clock period. XOR) is processed and stored in the memory 30 as a decryption statement. This results in decryption of the ciphertext encrypted with the initial round encryption.

That is, according to the above embodiment, the document encryption / decryption apparatus can be further strengthened by automatically setting the order of the round keys applied in the Rijndael encryption method using the secret key provided to the user. can do.

Therefore, according to the present invention, while maintaining the basic structure of the Rijndael encryption method, the application of the round key can be changed according to the secret key provided to the user, thereby increasing the secretion rate.

Meanwhile, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the technical spirit of the present invention.

As described above, according to the present invention, while maintaining the basic structure of the Rijndael encryption method as described above, the order of the round keys can be changed according to the secret key provided to the user, thereby increasing the degree of security.

    1 is a diagram for explaining a Rijndael encryption process that is generally used.

Figure 2 is a diagram showing the functional separation of the internal configuration of the encryption / decryption apparatus according to the present invention.

3 is a diagram showing functionally separating the internal structure of the round key sequence generation unit 40 shown in FIG.

4 is a view showing functionally separating the internal structure of the encryption / decryption unit 50 shown in FIG.

FIG. 5 is a diagram for explaining device-specific operations of the encryption / decryption unit 50 shown in FIG.

6 is a view for explaining the operation of the encryption / decryption apparatus according to the present invention.

******* Brief description of the main parts of the drawing *******

10: control unit, 40: round key sequence generation unit,

      50: cancer / decryption unit,

      41: first modular operation unit, 42: counter,

      43: adding unit, 44: second modular operation unit,

      51: round key providing unit, 52: first multiplexer,

      53: flip-flop, 54: round key composition,

      55: encryption processing unit, 56: decryption processing unit,

      57: second multiplexer.

Claims (6)

In the document encryption / decryption apparatus of Rijndael encryption method that performs the initial round and N rounds, and performs document encryption and decryption processing by applying a predetermined round key when performing the round, The encryption / decryption device performs document encryption and decryption processing by sequentially applying N + 1 round keys consisting of a secret key and N round keys for the initial round and N rounds, but the secret key information assigned to the device. Document encryption / decryption apparatus, characterized in that to apply sequentially from the round key corresponding to the. The method of claim 1, The document encryption apparatus includes round key order generating means for generating a predetermined round key address corresponding to a secret key based on a predetermined control signal; A round key table having a different start round key for each round key address is set to generate a round key sequentially from a start round key corresponding to a round key address applied from the round key order generating means, and based on the round key. Encryption / decryption means for performing document encryption and decryption, And control means for transmitting a control signal corresponding to document encryption or document decryption to the round key sequence generation means and the encryption / decryption means. The method of claim 2, The round key sequence generating means includes: a first modular operation unit for generating a remainder obtained by dividing the secret key information by N + 1; and counting from 0 to N when encrypting based on a control signal from the control means, and decrypting Includes a counter for discounting from N to 0, an adder for adding the first modular calculator and data applied from the counter, and a second modular calculator for generating a remainder obtained by dividing the data output from the adder by N + 1. Document encryption / decryption apparatus, characterized in that configured to. The method of claim 2, The encryption / decryption apparatus includes a round key providing unit that sequentially provides round key information corresponding to a round key address applied from a round key sequence generating means, and selects data to be encrypted and decrypted and data fed back based on a predetermined control signal. A first multiplexer for outputting, a round key synthesizing unit for exclusively processing the data output from the first multiplexer and a round key applied from the round key providing unit, and data applied from the round key synthesizing unit based on a predetermined control signal An encryption processing unit for performing data substitution (ByteSub) and RowRow processing, and outputting or outputting the row-shifted character data by performing a column combining (MixColumn), and encrypting the encrypted character data applied from the round key synthesis unit. Inverse data after inverse row shift processing based on a predetermined control signal A decryption processing unit for outputting by performing a substitution process or an inverse thermal synthesis process and outputting the inverse row shift and inverse data substitution process; and from the encryption processing unit and the decryption processing unit based on a predetermined control signal. And a second multiplexer for selectively providing applied data to an input of the first multiplexer. The method of claim 4, wherein When performing document encryption, the control means controls the output data of the encryption processing unit to be applied to the first multiplexer through the second multiplexer, The first multiplexer controls to output the original data during the first clock period and to output the document data applied from the second multiplexer from the second clock period to the N + 1 clock period. The data processing, row shift, and column synthesized character data are output to the second multiplexer from the first clock period to the N-1 clock period through the encryption processing unit, and the data replacement and row shift are performed during the Nth clock period. A document encryption / decryption apparatus, characterized in that for controlling the output of the processed character data to the second multiplexer. The method of claim 4, wherein When performing document decoding, the control means controls the output data of the decoding processing unit to be applied to the first multiplexer through a second multiplexer, The first multiplexer controls to output encrypted original data during a first clock period, and outputs data applied from a second multiplexer from a second clock period to an N + 1 clock period. The encryption processing unit outputs the row shift inverse transform and data exchange inverse transform processed data during the first clock period to the second multiplexer, and performs thermal synthesis inverse transform, row shift inverse transform, and data from the second clock period to the Nth clock period. And outputting the second inverse transform-processed data to a second multiplexer.