CN1190034C - A Block Cipher Encryption Method - Google Patents

Abstract

The present invention relates to a "swing" block cipher encryption method, comprising: grouping plaintext data into plaintext group data according to a certain fixed length; setting a key, and forming an S-box consisting of 256 elements from the key (replacement table); use the plaintext group data as the initial state of the shift register; move right by a certain number of beats according to the first nonlinear logic, then move left by a certain number of beats according to the second nonlinear logic, then move right and then left It stops when the preset number of rounds is repeated like swinging on a swing; the obtained state of the shift register is output as the ciphertext group corresponding to the plaintext group. The non-linear logical relationship between the plaintext and ciphertext groups is formed by the feedback variable passing through the S-box for many times. The state change of the shift register cleverly implements the mixing and diffusion of plaintext. This method has good performance against key-related attacks, linear attacks and differential attacks, and has the characteristics of safety, speed, easy implementation, concise and rigorous logical structure.

Description

A Block Cipher Encryption Method

technical field

The present invention relates to the technical field of information encryption, and more precisely relates to a method for forming a dynamic electronic password by utilizing electronic computer technology and coding technology.

Background technique

Encrypting information to prevent illegal personnel from obtaining confidential information in the information system is an extremely important technical means to ensure information security. A reliable encryption scheme can enable some sensitive information, even confidential information, to be safely and boldly transmitted on public channels or stored on media without protective measures.

The block encryption method is one of the important technical schemes for realizing information security in the form of modern electronic ciphers. The block cipher began (according to public information) with the DES that appeared in the mid-1970s. A prominent advantage of block ciphers over sequence ciphers is that the user's key can be reused. The realization technology of the block encryption algorithm is to first divide the plaintext data into several plaintext groups with a length of n bits, and then replace each n-bit plaintext group with another n-bit symbol to form an n-bit ciphertext (ie ciphertext group). The essential feature of the block encryption method is therefore a substitution operation. The decryption process is to invert the n-bit ciphertext group into the original n-bit plaintext group. Currently, the internationally recognized packet sizes n are 128 and 64.

With the development of block cipher technology, especially in the activities of soliciting cipher encryption standards in recent years, some block cipher algorithms have been published successively. For example, after NIST initiated the call for AE8 (Advanced Encryption Standard) in April 1997, 15 block cipher schemes were eligible for candidates; in January 2000, Europe began to collect European standards, and a total of 17 block cipher schemes participated in the election. At present, countries such as South Korea, Japan, and Russia have formulated their own encryption standards, and it is imperative for China to formulate its own encryption standards.

Obviously, if an excellent encryption scheme can be designed and widely served to the society, it will be beneficial to promote the construction of information infrastructure in various important fields of the national economy, which is naturally beneficial to the country and the people. Therefore, the invention can An excellent encryption scheme with technical features has become our wish.

In the collection of AES and European encryption standards, more than 30 block cipher schemes were collected, such as RIJNDAEL, RC6, MARS, TWOFISH, IDEA, SAFER++ and so on. These schemes basically represent the level, characteristics, style and basic direction of the current international block cipher algorithm. Of course, in addition to the above-mentioned more than 30 programs, there are some other programs.

The basic premise of block cipher algorithm design is to ensure and improve security performance. Looking at the existing block cipher schemes, the existing problems are that the speed of encryption and decryption is slow, and the logical structure of many algorithms is relatively complicated, which is difficult to program or realize on a microcircuit chip. Therefore, it is necessary to tap the potential in this area.

On the other hand, with the gradual maturity of the theory of shift registers in the past half century, shift registers are widely used to generate pseudo-random sequences, especially for generating long-period sequences with good statistical properties. The shift register sequence cipher is to apply the shift register to the modern sequence electronic cipher design, and use it as the basis for generating pseudo-random key stream sequence. In recent years, with the deepening of cipher coding and analysis technology, in many block cipher schemes, some schemes can be regarded as completing the plaintext conversion process by shift registers, but there are more or less slower encryption and decryption speeds. Slow and logical structure to implement more complex problems.

Contents of the invention

The purpose of the present invention is to design a block cipher encryption method, all using shift registers to realize the transformation process of plain ciphertext, which has the characteristics of safety and reliability, fast encryption and decryption speed, and easy implementation of algorithm logic.

The technical scheme that realizes the object of the present invention is such: a kind of block cipher encryption method is characterized in that comprising the following processing steps:

A. The plaintext data is divided into plaintext groups according to each group of M bytes (M * 8 bits), and M is an even number;

B. Key K is set, and a 256-yuan replacement table (S box) is formed by key K;

C. Set a M-level shift register on the Z/(2 ⁸ ) ring, and put the M byte plaintext group data into the M-level shift register correspondingly;

D. Carry out right-shift feedback, and number the stages of the M-stage shift register from left to right in order of level 0, level 1, ..., level M-1, and the shifting method of the left half is Feedback the content of the original level 0 to level 1, the content of the original level 1 to level 2, ..., the content of the original level M/2-2 to the level M/2-1 Level, the content of the original level M/2-1 is fed back to level 0, and the shift method of the right half is to feed back the content of the original level M/2 to the level M/2+1, the original M/2+ The content of level 1 is fed back to level M/2+2,..., the content of the original level M-2 is fed back to level M-1, and the content of the original level M/2 is obtained after passing through the S box The replacement value is added to the content of the original M-1 level and the content of the original M/2-1 level, and then fed back to the M/2 level after the sum of digital and analog 256, according to the set shift range j , and move the M-stage shift register to the right for a total of j beats;

E. For left-shift feedback, number the stages of the M-level shift register from left to right in order of level 0, level 1, ..., level M-1, and the shifting method of the right half is Feedback the content of the original level M/2+1 to the level M/2, the content of the original level M/2+2 to the level M/2+1,..., the original M- The content of level 1 is fed back to level M-2, the content of the original level M/2 is fed back to level M-1, and the shifting method of the left half is to feed back the content of the original level M/2-1 to level M /2-2 level, the content of the original M/2-2 level is fed back to the M/2-3 level,..., the content of the original level 1 is fed back to the 0th level, the original M/2 level The replacement value obtained after the content of level 1 passes through the S box is added to the content of the original level 0 and the content of the original level M/2, and then fed back to the level M/2-1 after the sum of the digital model 256 , according to the set shift range j, shift the M-stage shift register to the left for a total of j beats;

F. Repeat steps D and E until the preset number of right and left shifting rounds is reached and stop;

G. Use the contents of the M-level shift register after the shift is stopped as the ciphertext group obtained by encrypting the plaintext group.

The value of M is 8, 12, 16 or 20, and the corresponding packet sizes are 64 bits, 96 bits, 128 bits and 160 bits respectively.

Described step B further comprises the following processing steps:

b1. When the length of the set key K is less than 32 bytes, it is first cyclically derived to 32 bytes, marked as the 0th to 31st bytes;

b2. Shift the 0th to 31st byte key symbol itself to the left by 1 bit, that is, move the highest bit of each character to the lowest bit to form the 32nd to 63rd byte key, and then the 32nd byte From the byte to the 63rd byte, the key symbol itself is cyclically shifted to the left by 1 bit to form the key from the 64th byte to the 95th byte, and this step is performed continuously until a key with a length of 256 bytes is formed;

b3. Establish a key array unit numbered from 0 to 255, put a key with a length of 256 bytes into each array unit, and put it into the array unit in sequence;

b4. Establish transformation array units numbered from 0 to 255, and set their values to 0 to 255 respectively;

b5. Set up a memory unit m and a counting unit i, and agree that the initial value of m is 0, take the content in the counting unit of i as the address to find out the number in the current key array unit and the number in the current transformation array unit, Add them together with the value of the memory unit m, and use the sum as the new value of the memory unit m after modulo 256;

b6. be numbered as the new value of i in the step b5 and the m that obtains, the numerical value in the unit that address is m in the conversion array unit and the address are the numerical value exchange in the 255-i unit, the address in the conversion array unit is The value in the unit i is exchanged with the value in the unit whose address is 255-m;

b7. The new value of the memory unit m obtained in step b5 is shifted one bit in the left loop;

b8. Steps b5, b6, and b7 are repeatedly executed until the value of the counting unit i is counted from 0 to 255, and finally a 256-element replacement table (S box) is formed by transforming the array unit.

Passing through the S box in the steps D and E is to query the transformation array unit numbered with the numerical value according to the input value of the S box, and use the numerical value in the transformation array unit as the output value.

In the steps D and E, in each of the right-shift and left-shift transformations, the shift magnitude j is an arbitrarily preset natural number not less than M/2.

In the step F, the number of right shifting and left shifting wheels is not less than 2.

The method of the present invention adopts moving right to feed back a fixed beat, then moving left to feed back a fixed beat, then moving right to feed back another fixed beat, and then moving left to feed back another fixed beat, just like swinging on a swing, so it is called As a "swing" block cipher encryption method.

Like the method of the present invention, the shift register is used in the block cipher scheme, and the conversion process of the plaintext is all completed by the evolution of the shift register state, which is a unique technical solution.

The method of the present invention is a block encryption method implemented based on shift register state changes, and the entire process of its plaintext conversion is realized by shift register logic, and its main links include the feedback logic of the shift register, the setting of the S box, The shift amplitude (number of beats) of the shift register state and the number of right shift and left shift rounds are controlled. The plaintext group is used as the initial state of the shift register, and the obtained state of the shift register is output as the ciphertext group after multiple feedback recursions of nonlinear logic. Among them, the non-linear logical relationship between plaintext and ciphertext is formed because the feedback variable passes through the S-box for many times. If the plaintext transformation is regarded as a large permutation, the "swing" type block cipher encryption method provides a multi-time non-linear feedback of the shift register, which can resist both linear attack and differential attack. benign large replacement. Among them, the S-box is an important part of the nonlinear feedback logic, which is determined by the key. Users who know the key can freely push forward or reverse the state of the shift register. The process of reversely pushing the state of the shift register is the process of decryption. It is difficult for an attacker to separate the nonlinear feedback logic, or the key factor, from the highly complex multi-time nonlinear composition.

The security basis of the method of the present invention is that when the attacker does not occupy the S box, the pushing and evolution of the state of the shift register will not be possible.

The algorithm flow of the present invention is easy to realize by software programming, and is suitable for realization on a microcircuit chip.

The method of the present invention is a block cipher encryption method with the characteristics of safety, fastness, and easy implementation, and its main features are: the mixing and diffusion of plaintext and ciphertext are completed by the state transformation of the nonlinear shift register; , then move to the right for feedback, and then move to the left for feedback, which is a swing-style shifting method. In a specific implementation, besides 128 bits, the packet size of the plaintext data can also have multiple options such as 64, 96, and 160 bits.

Description of drawings

Fig. 1 is a schematic diagram of a right-shift feedback structure when a 16-stage shift register is selected;

Fig. 2 is a schematic diagram of a left-shift feedback structure when a 16-stage shift register is selected;

Fig. 3 is a schematic diagram of a right-shift feedback structure when an 8-stage shift register is selected;

FIG. 4 is a schematic diagram of a left-shift feedback structure when an 8-stage shift register is selected.

Detailed ways

Taking 128-bit grouping as an example, see Fig. 1 and Fig. 2, let Q be a 16-stage shift register on the ring Z/(2 ⁸ ). The process of generating a password includes two feedback modes: the right-shift feedback logic shown in the structure shown in FIG. 1 and the left-shift feedback logic shown in FIG. 2 .

11 and 12 in the figure are modulo 256 addition, It is an S box, and the S box is a substitution table composed of 256 elements preset by a key.

The encryption process is: put 16 bytes of plaintext data into the 0th to 15th levels of the shift register Q in sequence. The user can specify the number of rounds and the number of feedback beats in each round (that is, the echo amplitude) according to their own wishes. For example, if the number of rounds is set to 3, and the number of feedback beats in each round is 10, 9, and 8 in sequence, the Q Move the feedback to the right by 10 beats, then move Q to the left for 10 beats according to the logic in Figure 2, then move the feedback to the right by 9 beats according to the logic in Figure 1, then move the feedback to the left by 9 beats according to the logic in Figure 2, and then move the feedback to the right by 8 according to the logic in Figure 1 beat, and then follow the logical left shift feedback in Figure 2 for 8 beats, and then output the obtained 16-byte state of the 16-stage shift register as a ciphertext group.

When the feedback is shifted to the right, the shift method of the left half is to feed back the content of the original level 0 to level 1, the content of the original level 1 to level 2, ..., the content of the original level 6 Feedback to level 7, the content of the original level 7 is fed back to level 0. The shifting method of the right half is to feed back the content of the original level 8 to level 9, the content of the original level 9 to level 10, ..., the content of the original level 14 to level 15 . The replacement value of the original 8th level content after passing through the S box, the content of the original 15th level and the original 7th level content are summed and modulo 256, and then fed back to the 8th level.

When the feedback is shifted to the left, the shift method of the right half is that the content of the original 9th level is fed back to the 8th level, the content of the original 10th level is fed back to the 9th level, ..., the content of the original 15th level is fed back At the 14th level, the content of the original 8th level is fed back to the 15th level. The shifting method of the left half is that the content of the original level 7 is fed back to level 6, the content of the original level 6 is fed back to level 5, ..., the content of the original level 1 is fed back to level 0, The replacement value of the original level 7 content after passing through the S box, the content of the original level 0 and the content of the original level 8 are summed and modulo 256, and then fed back to level 7.

During implementation, the user can set the number of rounds and the number of displacement feedback beats by himself. The greater the number of rounds or the greater the number of beats, the higher the security and the slower the calculation speed.

Another example is when the packet is 64 bits (8 bytes), see Fig. 3 and Fig. 4, 21 and 22 in the figure are modulo 256 addition, and Q' is an 8-stage shift register on the ring Z/(2 ⁸ ). The levels are numbered from 0 to 7 from left to right. The encryption process includes two feedback modes, the right-shift feedback shown in the structure shown in FIG. 3 and the left-shift feedback shown in the structure shown in FIG. 4 .

Users can specify the number of rounds and the number of feedback beats in each round (ie the reverberation range) according to their wishes, for example, the number of rounds is 4 and the number of feedback beats in each round is 7, 5, 6, 5 in sequence. The encryption process is: put 8 bytes of plaintext data into the 0th to 7th levels of the shift register Q' in sequence, shift Q' to the right according to the logic in Figure 3 and feed back 7 beats, and then shift Q' to the left according to the logic in Figure 4 Feedback 7 beats, then move Q′ to the right for 5 beats according to the logic in Figure 3, then move Q’ to the left for 5 beats according to the logic in Figure 4, and then move to the right for 6 beats and left feedback according to the logic in Figure 3 and Figure 4 respectively 6 beats, and then respectively according to Fig. 3 and Fig. 4 logic right shift feedback 5 beats, left shift feedback 5 beats, and then the obtained 8-byte state of the shift register Q' is output as ciphertext.

Similarly, it is also possible to design a "swing" type packet encryption situation when the block size is 96 bits or 160 bits.

In the method of the present invention, the preset of the S box is an extremely important component, because its operation is carried out by one byte, that is, 8 bits are entered and 8 bits are output, so the S box is a 256-element replacement table preset by the key (28=256). The preset steps are as follows:

1). If the length of the key is less than 32 bytes, it is firstly derived into 32 bytes through cyclic padding, and the 32 bytes are numbered as 0 to 31;

2). Shift the 0th to 31st byte key symbol itself to the left by 1 bit to form the 32nd to 63rd byte key, and shift the 32nd to 63rd byte key symbol to the left by 1 bit to form the 32nd to 63rd byte key symbol itself The 64th to 95th byte key, ..., and so on, until the 224th to 255th byte key is derived, and the 256 byte key is correspondingly put into the key array unit Key[0 ]-Key[255], set any one of the key array units as Key[i];

3). Set the transformation arrays S[0]-S[255], and preset them as values 0-255 respectively, set any one of the transformation arrays as S[i], let m be a memory unit, and Initially preset m=0, then, do the following operations for i=0 to 255:

{Assign a new value to m: m←(m+Key[i]+s[i]) mod 256;

Exchange S[m] and S[255-i];

Exchange S[i] and S[255-m];

m Left circular shift one bit;

}

The S[0]-S[255] obtained through the above operations is the S-box set by the key device, and obviously S[0]-S[255] is a reversible substitution table.

The following takes the key as the hexadecimal symbol "61 62 63 64 65 66 67 68 69 6a" as an example, that is, the keyboard enters the eight-unit ASCII character a b c d e f g h i j, and the case of grouping by 128 bits is given The basic process and intermediate results of encrypting a set of plaintext.

First generate the S-box.

Round-robin derivation of a 10-byte key into 32 bytes, i.e. "61 62 63 64 65 66 67 68 69 6a61 62 63 64 65 66 67 68 69 6a 61 62 63 64 65 66 67 68 69 6a 61 62";

Then do 2×256=512 transpositions on the S box, every 64 transpositions, shift the 32-byte key to the left by one bit, that is, the highest bit of each byte is feedback shifted to the lowest bit of the byte bit, the last generated S[0]-S[255] is:

e5 a7 eb a0 63 7e c2 e4 d0 4e f5 e1 41 0e 73 1c

c1 a6 99 c7 fe 03 4f 5a da ce 64 71 45 d6 00 6a

ee f7 e9 c6 52 d4 7b bc 48 2d 56 6d a8 a4 93 20

6f 36 85 46 9d 67 96 c5 22 1d 19 ef c8 27 b5 97

9f 82 ae 75 3f bf b2 d7 87 ac 76 42 0f 2e e7 79

50 3c 7f 0d b6 fd 21 13 e8 8b a3 b4 f6 dc fa b3

91 06 26 8f 30 5e f3 54 2c 3b 61 65 cc 15 2a 35

83 5d 6b 8d aa f4 bb ed 77 cb f8 47 32 04 e0 24

db 1f fb cd b8 07 34 88 12 44 0b 55 72 94 a2 7c

ca d5 ea 33 9a 9e c4 d3 ab 0c a1 cf 70 d9 f9 6e

4c 05 23 09 4b 5c 74 17 ec de 02 49 f2 80 c3 af

86 18 d1 f0 bd 89 53 78 28 4d 40 c0 8a 51 7d 60

68 4a d8 37 10 e6 e2 dd 3a 69 98 62 b9 7a c9 90

df 6c 5b 57 92 a9 d2 b7 43 84 2b ad 39 16 08 11

95 ff 29 ba 8e 9b 31 25 a5 b0 fc 01 38 66 59 3e

e3 8c f1 be 1e 0a b1 2f 1b 3d 81 9c 5f 14 58 1a.

Use P to represent the plaintext, use T and U to represent the intermediate results of the shift register, and use C to represent the ciphertext. When the plaintext expressed in hexadecimal is "61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f 70", the change process from plaintext to ciphertext is:

Plaintext P=(61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f 70);

According to the structure in Figure 1, move the feedback to the right by 10 beats

P'＝(67 68 61 62 63 64 65 66 5f d2 d3 a3 47 4f 52 ad);

According to the structure in Figure 2, move the feedback to the left by 10 beats

T＝(bc 8f 26 2e 4a 89 5c 4f d3 a3 47 4f 52 ad 5f d2);

According to the structure in Figure 1, move the feedback to the right for 9 beats

T'＝(4f bc 8f 26 2e 4a 89 5c eb 7f b3 fa 73 5c bb 32);

According to the structure in Figure 2, move left to feed back 9 beats

U＝(aa 44 5f 54 5c 3a a7 32 7f b3 fa 73 5c bb 32 eb);

According to the structure in Figure 1, move the feedback to the right for 8 beats

C'＝(aa 44 5f 54 5c 3a a7 32 69 ba ae 8b 96 a9 5b 41);

According to the structure in Figure 2, move to the left and feed back 8 beats to get the ciphertext

C＝(98 a9 eb e0 87 6b 67 c7 69 ba ae 8b 96 a9 5b 41).

The packet encryption generation process of "swinging on a swing" formula of the present invention is easy to realize by software programming, for example, when programming in C language, when the number of rounds is set to 3, the number of right shift and left shift beats of each round is respectively 10, In the case of 9 and 8, the encryption and decryption speed on the PIII500 microcomputer can reach 230Mb/s, and the required storage unit is less than 300 bytes, that is, the S box occupies 256 bytes, and the key symbol actually occupies 32 bytes, and the generated The 32-byte space after the S box can also be used for shift register status and intermediate result storage.

The method of the present invention, through the basic analysis of the key avalanche effect and the plaintext avalanche effect, shows that it has good performance against key-related attacks, linear attacks and differential attacks. In addition to being safe, fast, and easy to implement, its The most prominent feature is that the algorithm logic structure is concise and rigorous, which can effectively implement the mixing and diffusion of plaintext.

The "swing" type block cipher encryption method of the present invention is faster than well-known algorithms such as RIJNDAEL, MARS, TWOFISH, etc. in terms of encryption and decryption speed. The logic structure of the algorithm is simpler than them, and it is easy to program and is also very suitable for microchip accomplish.

Claims (6)

1. A block cipher encryption method, characterized in that comprising the following processing steps: A. Divide the plaintext data into plaintext groups according to each group of M bytes, and M is an even number; B. Set the key K, and form a 256-yuan replacement table S box from the key K; C. Set a M-level shift register on the Z/(2 ⁸ ) ring, and put the M byte plaintext group data into the M-level shift register correspondingly; D. Carry out right-shift feedback, and number the stages of the M-stage shift register from left to right in order of level 0, level 1, ..., level M-1, and the shifting method of the left half is Feedback the content of the original level 0 to level 1, the content of the original level 1 to level 2, ..., the content of the original level M/2-2 to the level M/2-1 Level, the content of the original level M/2-1 is fed back to level 0, and the shift method of the right half is to feed back the content of the original level M/2 to the level M/2+1, the original M/2+ The content of level 1 is fed back to level M/2+2,..., the content of the original level M-2 is fed back to level M-1, and the content of the original level M/2 is obtained after passing through the S box The replacement value is added to the content of the original M-1 level and the content of the original M/2-1 level, and then fed back to the M/2 level after the sum of digital and analog 256, according to the set shift range j , and move the M-stage shift register to the right for a total of j beats; E. For left-shift feedback, number the stages of the M-level shift register from left to right in order of level 0, level 1, ..., level M-1, and the shifting method of the right half is Feedback the content of the original level M/2+1 to the level M/2, the content of the original level M/2+2 to the level M/2+1,..., the original M- The content of level 1 is fed back to level M-2, the content of the original level M/2 is fed back to level M-1, and the shifting method of the left half is to feed back the content of the original level M/2-1 to level M /2-2 level, the content of the original M/2-2 level is fed back to the M/2-3 level,..., the content of the original level 1 is fed back to the 0th level, the original M/2 level The replacement value obtained after the content of level 1 passes through the S box is added to the content of the original level 0 and the content of the original level M/2, and then fed back to the level M/2-1 after the sum of the digital model 256 , according to the set shift range j, shift the M-stage shift register to the left for a total of j beats; F. Repeat steps D and E until the preset number of right and left shifting rounds is reached and stop; G. Use the contents of the M-level shift register after the shift is stopped as the ciphertext group obtained by encrypting the plaintext group. 2. The method according to claim 1, characterized in that: the value of M is 8, 12, 16 or 20, and the corresponding packet sizes are 64 bits, 96 bits, 128 bits and 160 bits respectively. 3. The method according to claim 1, characterized in that: described step B further comprises the following processing steps: b1. When the length of the set key K is less than 32 bytes, it is first cyclically derived to 32 bytes, marked as the 0th to 31st bytes; b2. Shift the 0th to 31st byte key symbol itself to the left by 1 bit, that is, move the highest bit of each character to the lowest bit to form the 32nd to 63rd byte key, and then the 32nd byte From the byte to the 63rd byte, the key symbol itself is cyclically shifted to the left by 1 bit to form the key from the 64th byte to the 95th byte, and this step is performed continuously until a key with a length of 256 bytes is formed; b3. Establish a key array unit numbered from 0 to 255, put a key with a length of 256 bytes into each array unit, and put it into the array unit in sequence; b4. Establish transformation array units numbered from 0 to 255, and set their values to 0 to 255 respectively; b5. Set up a memory unit m and a counting unit i, and agree that the initial value of m is 0, take the content in the counting unit of i as the address to find out the number in the current key array unit and the number in the current transformation array unit, Add them together with the value of the memory unit m, and use the sum as the new value of the memory unit m after modulo 256; b6. be numbered as the new value of i in the step b5 and the m that obtains, the numerical value in the unit that address is m in the conversion array unit and the address are the numerical value exchange in the 255-i unit, the address in the conversion array unit is The value in the unit i is exchanged with the value in the unit whose address is 255-m; b7. The new value of the memory unit m obtained in step b5 is shifted one bit in the left loop; b8. Steps b5, b6, and b7 are repeatedly executed until the value of the counting unit i is counted from 0 to 255, and finally a 256-element substitution table S box is formed by transforming the array unit. 4. The method according to claim 1, characterized in that: passing through the S box in the steps D and E is to query the transformation array unit numbered with the numerical value according to the input value of the S box, and transfer the transformation array unit in the transformation array unit value as the output value. 5. The method according to claim 1, characterized in that: in the steps D and E, in each of the described right-shift and left-shift transformations, the shift magnitude j is arbitrarily preset and not less than M/ The natural number of 2. 6. The method according to claim 1, characterized in that: in the step F, the number of right-shift and left-shift wheels is not less than two.

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