CN1258148C - Encryption, decryption method using high security level symmetry secret key algorithm and its encipherer - Google Patents

Abstract

The encryption and decryption method and the encryptor of the high-security symmetric key algorithm are a kind of symmetric key DSP encryptor. The encryption method is composed of N rounds of encryption rounds connected in series. The encryption order of each encryption round is Bit transformation, S-box replacement column mixed transformation, subkey modulo 2 plus transformation, the final output of each encryption round is the subkey modulo 2 plus transformation, and then the input of the next encryption round is the row shift transformation. The decryption method is as follows: N rounds of decryption rounds are combined in series, and the decryption sequence of each decryption round is subkey modulo 2 addition transformation, inverse row mixing transformation, inverse S-box substitution transformation, and inverse row shift transformation. The final output of each decryption round is The retrograde shift transformation is connected to the input of the next decryption round, which is the subkey modulo 2 plus transformation. The encryptor is composed of a DSP module, a FLASH module, and a McBSPO expansion port. This method can increase the encryption speed by 2.16 times and the decryption speed by 2 times. .

Description

Encryption and decryption method and encryptor of high security level symmetric key algorithm

1. Technical field:

The invention is a symmetric key DSP encryptor, which belongs to the technical field of information encryption protection.

2. Technical background

Due to the continuous improvement of computer computing power and the development of Internet-based distributed computing, it poses a huge threat to the DES algorithm with a key length of only 56 bits. Therefore, on April 15, 1997, the National Institute of Standards and Technology (NIST) launched Solicit activities for the Advanced Encryption Standard (AES) algorithm, and announced Rijndael on October 2, 2000 as a new generation of data encryption standards in the United States, aiming to protect the transmission of sensitive and non-confidential information of the government and other organizations.

The Rijndael algorithm is an iterative block cipher with a data block length of 128 bits and a variable key length. The key block length can be 128, 192 or 256 bits respectively. Since the Rijndael algorithm is derived from the Square algorithm, its structure is highly flexible and easy to expand.

However, the Rijndael algorithm also has the slow speed of byte modular multiplication, and the key length is relatively short (only 256 bits at the longest), which cannot meet the high security level. In addition, the original algorithm has the disadvantage of unequal encryption and decryption speed.

The DSP-based special-purpose encryptor using the Rijndael algorithm as the core has not yet appeared on the market. Extending the Rijndael algorithm and making it an encryptor that can run quickly on DSP devices is also a blank at home and abroad.

3. Contents of the invention

1. Technical issues

The purpose of the present invention is to provide a kind of encryption, decryption method and encryptor of a kind of high security level symmetric key algorithm that can increase encryption speed more than 2 times, simple in structure, low in cost, easy to operate

2. Technical solution

The encryption and decryption method of the high-security level symmetric key algorithm of the present invention is composed of N rounds of encryption rounds connected in series, and the encryption sequence of each encryption round is row shift transformation, S-box substitution column mixing transformation, and subkey Modulo 2 plus transformation, the final output of each encryption round is the subkey modulo 2 plus transformation, then the input of the next encryption round is row shift transformation, the plaintext and the seed key are added to the data/key, and the data/key phase The result of the addition is sent to the row shift transformation of the 0th round, and at the same time, the encryption wheel key W _i generated by the seed key through key diffusion 7 is respectively sent to the last transformation of each encryption round, that is, the subkey modulo 2 plus transformation; finally The encryption sequence of one encryption round is S-box substitution transformation, row shift transformation, subkey modulo 2 plus transformation, and the subkey modulo 2 plus transformation of the last round of encryption outputs the ciphertext.

The transformation method of the row shift transformation is: the row shift transformation performs a circular shift operation on the bytes of each row of the state separately, and satisfies the following relationship: the 0th row and the 4th row are not shifted; the 1st row and the 5th row Shift 1 byte; if Nb=4 or Nb=6 in the 2nd and 6th rows, shift 2 bytes, otherwise shift 3 bytes; if Nb=4 or Nb=6 in the 3rd and 7th rows , shift 3 bytes, otherwise shift 4 bytes.

The transformation method of S-box replacement column mixed transformation is: multiply each byte of S-box by 02, 03, 04, 05 modulo m(x) in advance to form 4 one-dimensional extended S-box replacement tables, (MUL02, MUL03 , MUL04, MUL05), rearrange the transformation order of the encryption round of the extended algorithm, reverse the order of S-box substitution and row shift, and merge the S-box substitution transformation into column mixing transformation. When transforming, first find the transformed value of each column byte of the state from each extended S-box replacement table according to the coefficients of the column mixed transformation, and then perform XOR operation on these values, and wait until a certain byte of the state is transformed into a new value value; by analogy, you can get the new value after the other bytes of the state are transformed. The transformation method of the subkey modulo 2 plus transformation is as follows: the subkey modulo 2 plus transformation is to add the wheel key modulo 2 obtained by key diffusion to each byte in the state.

The number of encryption rounds Nr is jointly determined by Nk and Nb, that is, the value of Nr is equal to the larger value of Nk and Nb plus 6, so that Nr is 10, 12 or 14.

Key diffusion consists of two processes:

1) Key diffusion: the seed key is diffused into a diffusion key;

2) The selection of the round key: the sub-key used in each round is selected from the diffusion key.

The difference from the original algorithm is:

Each selected word is 64bits or 8 bytes

The round constant is composed of 8-byte constants, the first 7 bytes of these 8 bytes are 0, the last byte of the first round is 01, and the last byte of the remaining rounds is the number of round constants of the previous round. The last byte is formed by modulo multiplying '02'.

The decryption method is as follows: it is composed of N rounds of decryption rounds in series. The decryption sequence of each decryption round is subkey modulo 2 addition transformation, inverse column mixing transformation, inverse S-box substitution transformation, and inverse row shift transformation. Each decryption The final output of the round is the reverse shift transformation, which is the input of the next decryption round, that is, the subkey modulo 2 addition transformation. The ciphertext and the seed key are added by data/key, and the result of the data/key addition is sent to the 0th round. The subkey modulo 2 plus transformation of the round, and the decryption wheel key W _i generated by the seed key through key diffusion are respectively sent to the first transformation of each decryption round, that is, the subkey modulo 2 plus transformation; The decryption sequence of the decryption round is the subkey modulo 2 addition transformation, the inverse S-box substitution transformation, and the reverse shift transformation, and the last round of decryption round reverses the shift transformation to output the plaintext.

The inverse mixed transformation transformation method is as follows: the order of the four transformations in each round is not changed, but only the inverse mixed transformation is modified, and four sheets from 0 to 255 are pre-programmed with 02, 03, 04, 05 modulo m(x ) multiplied one-dimensional factor table (LUT02, LUT03, LUT04, LUT05), when transforming, first find the value after modular multiplication of each column byte of the state from each multiplier factor table according to the coefficient of column mixed inverse transformation, and then Perform XOR operation on these values, wait until the new value of a certain byte of the state after inverse transformation, and so on, you can get the new value of other bytes of the state after transformation.

The symmetric key algorithm encryption device with high security level is composed of DSP module, FLASH module and McBSP0 expansion port. "D15-D0" of DSP module is connected with "D15-D0" end of FLASH module, and " A15-A0" is connected to the "A15-A0" end of the FLASH module, "MSTRB, R/W" of the DSP module is connected to the "WE" end of the FLASH module through the AND gate, and the "MSTRB" of the DSP module solves the Input terminal, the output terminal of this NAND gate and " R/W " of DSP module (13) connect two input terminals of a NAND gate respectively, the output terminal of this NAND gate connects " OE " end of FLASH module, DSP The "BCLKR0, BFSR0, BDR0, BCLKX0, BFSX0, BDX0, INT0, INT1, IACK" of the module are connected to the McBSP0 expansion port.

3. Technical effects

The present invention respectively proposes a rapid implementation scheme for the encryption process and decryption process of an extended Rijndael algorithm, and applies the rapid implementation scheme to a high-security symmetric key algorithm encryptor composed of a common TMS320VC5402 hardware platform , the encryption speed can be increased by 2.16 times, and the decryption speed can be increased by 2 times through the actual measurement of the encryption device. If combined with DSPs technology, the encryption speed of the encryptor can be increased by 5.80 times, and the decryption speed can be increased by 5.50 times. At the same time, encryption and decryption are approximately equal.

4. Description of drawings

Fig. 1 is a schematic flow chart of the encryption method of the present invention. Among them: row shift transformation 1, S box substitution_column mixing transformation 2, subkey modulo 2 plus transformation 3, plaintext 4, seed key 5, data/key addition 6, key diffusion 7.

Fig. 2 is a schematic flow chart of the decryption method of the present invention. Among them are: inverse column mixing transformation 9, inverse S-box substitution transformation 10, inverse row shift transformation 11, and ciphertext 12.

Fig. 3 is a schematic structural diagram of the encryptor of the present invention. Among them are: DSP module 13, FLASH module 14, McBSP0 expansion port 15.

Fig. 4 is the realization circuit diagram of the encryptor of the present invention.

5. Specific implementation

The encryption and decryption method of the high security level symmetric key algorithm of the present invention is composed of N rounds of encryption rounds connected in series. Key modulo 2 plus transformation, the final output of each encryption round is the subkey modulo 2 plus transformation, and then the input of the next encryption round is line shift transformation, the plaintext and the seed key are added to the data/key, and the data/key The result of the addition is sent to the row shift transformation of the 0th round, and at the same time, the encryption wheel key Wi generated by the seed key through key diffusion 7 is sent to the last transformation of each encryption round, that is, the subkey modulo 2 plus transformation; finally The encryption sequence of one encryption round is S-box substitution transformation, row shift transformation, subkey modulo 2 plus transformation, and the subkey modulo 2 plus transformation of the last round of encryption outputs the ciphertext.

The transformation method of the row shift transformation is: the row shift transformation performs a circular shift operation on the bytes of each row of the state separately, and satisfies the following relationship: the 0th row and the 4th row are not shifted; the 1st row and the 5th row Shift 1 byte; if Nb=4 or Nb=6 in the 2nd and 6th rows, shift 2 bytes, otherwise shift 3 bytes; if Nb=4 or Nb=6 in the 3rd and 7th rows , shift 3 bytes, otherwise shift 4 bytes.

The transformation method of the S-box replacement column mixed transformation is as follows: each byte of the S box is multiplied by 02, 03, 04, and 05 modulo m(x) in advance to form 4 one-dimensional extended S-box replacement_column mixed transformation tables (MUL02 , MUL03, MUL04, MUL05), rearrange the transformation sequence of the encryption round of the extended algorithm, reverse the order of the S-box replacement column mixing transformation and row shifting, and merge the S-box replacement column mixing transformation into the column mixing transformation. When transforming, first find the transformed value of each column byte of the state from each extended S-box replacement table according to the coefficients of the column mixed transformation, and then perform XOR operation on these values, and wait until a certain byte of the state is transformed into a new value value; by analogy, you can get the new value after the other bytes of the state are transformed.

The transformation method of the subkey modulo 2 plus transformation is as follows: the subkey modulo 2 plus transformation is to add the wheel key modulo 2 obtained by key diffusion to each byte in the state.

The number of encryption rounds Nr is jointly determined by Nk and Nb, that is, the value of Nr is equal to the larger value of Nk and Nb plus 6, so that Nr is 10, 12 or 14.

Key diffusion consists of two processes:

1) Key diffusion: the seed key is diffused into a diffusion key;

2) The selection of the round key: the sub-key used in each round is selected from the diffusion key.

The difference from the original algorithm is:

Each selected word is 64bits or 8 bytes

The round constant is composed of 8-byte constants, the first 7 bytes of these 8 bytes are 0, the last byte of the first round is 01, and the last byte of the remaining rounds is the number of round constants of the previous round. The last byte is shifted left by 1 bit.

According to the characteristics of Rijndael, the present invention designs an extended Rijndael algorithm whose data and key lengths can be 256/384/512 bits, so that the encryption and decryption speeds are basically equal. On this basis, fast implementation schemes are proposed for the encryption and decryption processes of the extended algorithm, respectively, to solve the shortcomings of the slow speed of byte modular multiplication including the original algorithm and the extended algorithm. Transplant the algorithm to the ordinary DSP hardware platform (the platform takes TMS320VC5402 as the core, including the peripheral basic data input and output channels), and combine the characteristics of DSPs memory, adopt the positioning method of the code segment, and use the corresponding support software to provide The advanced code optimizer comprehensively optimizes the extended Rijndael algorithm, and the speed of encryption and decryption has been greatly improved.

Quick implementation plan:

In the column mixing transformation (MixColumn) of the extended Rijndael algorithm, 64 Nb (Nb is the length of the data block divided by 64) byte modular multiplication operations are required, and the calculation amount of the program is 192 Nb table lookup operations and 64 ·Nb times of addition operations on GF(2 ⁸ ), the amount of computation is relatively large. If we convert these 192·Nb times of modular multiplication operations into 64·Nb times of look-up table operations, the operation cost will be greatly reduced. According to the characteristics of each round of encryption and decryption of the extended Rijndael algorithm, this patent proposes fast implementation schemes respectively.

A quick implementation of the encryption process:

Since the row shift transformation is a linear transformation, it does not change the value of the elements of each input state, but only rearranges the elements of the 1st, 2nd, 3rd, 5th, 6th, and 7th rows, so the extended The transformation order of the encryption round of the algorithm is rearranged, and the order of S-box substitution and row shifting is reversed. According to (1) and (2), the S-box substitution transformation can be combined into the column mixing transformation.

s'(x)=a(x)s(x)mod(x ⁸ +1) (1)

in

a(x)＝{03}x ⁷ +{05}x ⁶ +{03}x ⁵ +{02}x ⁴ +{02}x ³ +{04}x ² +{02}x+{02} (2 )

According to formula (2), the following formula can be obtained:

MUL02[·]＝S[·]·02mod m(x) (3)

MUL03[·]＝S[·]·03mod m(x) (4)

MUL04[·]＝S[·]·04mod m(x) (5)

MUL05[·]＝S[·]·05mod m(x) (6)

According to (3), (4), (5) and (6), four one-dimensional extended S-box permutation tables can be compiled respectively, and their elements are the elements of S-box mod m(x) times 02, mod m(x ) by 03, mod m(x) by 04 and mod m(x) by 05.

A quick implementation of the decryption process:

The decryption method is as follows: it is composed of N rounds of decryption rounds in series. The decryption sequence of each decryption round is subkey modulo 2 addition transformation, inverse column mixing transformation, inverse S-box substitution transformation, and inverse row shift transformation. Each decryption The final output of the round is the reverse shift transformation, which is the input of the next decryption round, that is, the subkey modulo 2 addition transformation. The ciphertext and the seed key are added by data/key, and the result of the data/key addition is sent to the 0th round. The subkey modulo 2 plus transformation of the round, and the decryption wheel key W _i generated by the seed key through key diffusion are respectively sent to the first transformation of each decryption round, that is, the subkey modulo 2 plus transformation; The decryption sequence of the decryption round is the subkey modulo 2 addition transformation, the inverse S-box substitution transformation, and the reverse shift transformation, and the last round of decryption round reverses the shift transformation to output the plaintext.

The inverse mixed transformation transformation method is as follows: the order of the four transformations in each round is not changed, but only the inverse mixed transformation is modified, and four sheets from 0 to 255 are pre-programmed with 02, 03, 04, 05 modulo m(x ) multiplied one-dimensional factor table (LUT02, LUT03, LUT04, LUT05), when transforming, first find the value after modular multiplication of each column byte of the state from each multiplier factor table according to the coefficient of column mixed inverse transformation, and then Perform XOR operation on these values, wait until the new value of a certain byte of the state after inverse transformation, and so on, you can get the new value of other bytes of the state after transformation.

The order of the four transformations in each round is not changed, only the inverse column hybrid transformation is modified, but the basic idea is not changed. A certain state s'=(s' _{i, j} , i=0, 1...7, j=0, 1,...Nb-1) is transformed into s=(si _{, j} , i=0, 1...7, j=0, 1,...Nb-1), then the relationship between them is shown in formula (7) and formula (8).

s(x)=a ^-1 (x)s′(x)mod(x ⁸ +1) (7)

in

a ^-1 (x)＝{03}x ⁷ +{04}x ⁶ +{03}x ⁵ +{03}x ⁴ +{02}x ³ +{05}x ² +{02}x+{03} (8)

According to formula (8), the following formula can be obtained:

LUT02[i]＝i·02mod m(x) (9)

LUT03[i]=i·03mod m(x) (10)

LUT04[i]＝i·04mod m(x)

LUT05[i]=i·05mod m(x) (12)

(9)～(12) where i=0, 1, 2...255

Therefore, LUT02, LUT03, LUT04, and LUT05 are essentially an ordinary mod m(x) multiplication factor table, and these four one-dimensional tables are used for column mixing inverse transformation.

Implementation of encryption and decryption algorithm and code optimization on TMS320VC5402:

There are two kinds of on-chip memory in TMS320VC5402: Dual addressing memory (DARAM) and single addressing memory. Dual addressable memory is characterized by allowing the CPU to access it twice in a single cycle. Single-addressable memory comes in two forms: (1) single-addressable read/write memory (SARAM), (2) single-addressable read-only memory (ROM or DROM), and the CPU can access each memory location in a single cycle once. Both types of memory can be mapped into program space and data space. In addition, TMS320VC5402 can be plugged with off-chip memory, but the CPU needs at least two cycles to access the off-chip memory unit once. Compared with off-chip memory, on-chip memory has the advantages of not needing to insert wait state, low cost and power consumption.

Correspondingly, TI provides a corresponding code development integrated environment - Code ComposerStudio (CCS), which integrates code generation tools and debugging tools, and can provide processor information and monitor program performance. CCS can use all tools in one control window.

CCS has its own code optimizer Optimizer, which can optimize all source codes contained in CCS Project at 4 different levels: register (Register) level optimization, local variable (Local) level optimization, global variable (Global) level Optimization, file (FILE) level optimization, the scope and degree of optimization of these four levels are gradually expanded and deepened.

Combined with our proposal 1, scheme 2, program segment mapping method and CCS own program optimizer, we implemented the extended Rijndael encryption and decryption algorithm with ANSI C language on the TMS320VC5402 hardware platform, and carried out different levels of algorithm Optimization has greatly improved the operation speed of the encryptor.

Extended Rijndael algorithm:

The data block length and seed key length that can be realized by this extended algorithm are both 256/384/512bits. The intermediate result of the encryption, that is, the state (State) is a matrix with 8 rows and Nb columns, where Nb is the length of the data block divided by 64. The encryption key is a matrix with 8 rows and Nk columns, where Nk is the key length divided by 64.

The number of rounds of encryption (Nr) is determined by (13).

Nr＝max{Nk，Nb}+6

Since Nk, Nb ∈ {4, 6, 8}, so Nr ∈ {10, 12, 14}

The encryption process consists of the following parts:

1. An initial round key modulo 2 plus.

2. Nr-1 round: S-box substitution transformation (SubBytes), row shift transformation (ShiftRows), column mixing transformation (MixColumns) and subkey modulo 2 addition (Key Addition) are performed in sequence.

3. An end round: S-box substitution transformation, row shift transformation and subkey modulo 2 addition are performed sequentially, excluding column mixing transformation.

The encryption round is the same as the original algorithm, consisting of four transformations: S-box substitution transformation, row shift transformation, column mixing transformation and subkey modulo 2 addition.

S-box substitution transformation:

Like the original algorithm, the S and substitution transformation is a non-linear byte substitution transformation. This transformation uses the same S-box as the original algorithm (a one-dimensional table composed of 256 elements), and retrieves the corresponding replacement value in the S-box according to the value of each byte of the intermediate result.

S-box construction:

An S-box is a reversible permutation table consisting of two sub-transformations:

1. The multiplicative inverse over the finite field GF(2 ⁸ ), the mapping of the element {00} is itself.

2. Affine on finite field GF(2), as shown in formula (14).

b′ _i = b _i b _(i+4)mod8 b _(i+5)mod8 b _(i+6)mod8 b _(i+7)mod8 c _i (14)

Wherein, 0≤i≤8, b _i is the ibit of the transformed byte, {c ₇ c ₆ c ₅ c ₄ c ₃ c ₂ c ₁ c ₀ }=(63h)=(01100011b}.

Row shift transformation:

The row shift transformation performs a circular shift operation on the bytes of each row of the state separately, and the number of shifted bytes in each row satisfies the following relationship:

s' _{r, c} = s _{r, (c+shift(r, Nb)) mod Nb} , 0<r<8, 0≤c<Nb (15)

The shift value shift(r, Nb) is determined by the row number of the byte in the state and the column number (Nb) of the state, and they satisfy the following relationship: row 0 and row 4 are not shifted, other rows are right The shifted value satisfies the table below. r=1 r=2 r=3 r=5 r=6 r=7 Nb=4 1 2 3 1 2 3 Nb=6 1 2 3 1 2 3 Nb=8 1 3 4 1 3 4

Column blend transformation:

This part is quite different from the original algorithm. Column blending transformations perform column-by-column operations on the state. Each column of the state is regarded as an 8-term polynomial s(x), the coefficient of the polynomial is on GF(2 ⁸ ), and it is multiplied with a fixed polynomial a(x) modulo x ⁸ +1, that is, the column mixing transformation satisfies the following relation:

s'(x)=a(x)s(x)mod(x ⁸ +1) (16)

Among them, s(x), s’(x) are the input and output of the column transformation corresponding to the state, respectively,

a(x)＝{03}x ⁷ +{05}x ⁶ +{03}x ⁵ +{02}x ⁴ +{02}x ³ +{04}x ² +{02}x+{02} (17 )

In the inverse transformation, the transformation relation of the following formula is satisfied.

s(x)=a ^-1 (x)s′(x)mod(x ⁸ +1) (18)

in

a ^-1 (x)＝{03}x ⁷ +{04}x ⁶ +{03}x ⁵ +{03}x ⁴ +{02}x ³ +{05}x ² +{02}x+{03} (19)

It can be seen from (17) and (19) that the coefficients of a(x) and a ^-1 (x) are not 0, and both are distributed between 1 and 5, with an upper bound of 5. Compared with the original algorithm (the upper bound of the coefficients of column mixing transformation is 3, and the upper bound of the inverse transformation is 14), the coefficient distribution of the extended algorithm is very concentrated, and it has stronger diffusion ability and anti-attack ability. From our test of the algorithm overhead, we can see that the encryption and decryption speeds are approximately equal; the main reason is that the coefficients are distributed in the same and very concentrated interval.

Subkey modulo 2 plus transformation:

Same as the original algorithm, the subkey modulo 2 plus transformation is to add the wheel key modulo 2 obtained by key diffusion to each byte in the state. Its conversion relation satisfies the following formula.

[ _{s'0, c} , _{s'1, c} , _{s'2, c} , _{s'3, c} , _{s'4, c} , _{s'5, c} , _{s'6, c} , _{s'7, c} ]= [s _{0, c} , s _{1, c} , s _{2, c} , s _{3, c} , s _{4, c} , s _{5, c} , s _{6, c} , s _{7, c} ]xor[w _round*Nb+c ] (20)

Wherein, 0≤c<Nb, 0≤round<Nr, [w _i ] is the round key formed by key diffusion.

Key Diffusion:

Like the original algorithm, key diffusion consists of two processes:

1. Key diffusion: the seed key is diffused into a diffusion key;

2. Selection of round keys: The sub-keys used in each round are selected from the diffusion keys.

The difference from the original algorithm is:

The word selected each time is 64bits (8 bytes) instead of 32bits (4 bytes);

The wheel constant is defined by (21).

Rcon[i]=(RC[i], {00}, {00}, {00}, {00}, {00}, {00}, {00}) (21)

The value of RC[i] is determined by the following two formulas:

RC[1]='01' (22)

RC[i]=x·(RC[i-1])=x ^(x-1) (23)

The symmetric key algorithm encryption device with high security level is composed of DSP module, FLASH module and McBSP0 expansion port. "D15-D0" of DSP module is connected with "D15-D0" end of FLASH module, and " A15-A0" is connected to the "A15-A0" end of the FLASH module, "MSTRB, R/W" of the DSP module is connected to the "WE" end of the FLASH module through the AND gate, and the "MSTRB" of the DSP module solves the Input terminal, the output terminal of this NAND gate and " R/W " of DSP module (13) connect two input terminals of a NAND gate respectively, the output terminal of this NAND gate connects " OE " end of FLASH module, DSP The "BCLKR0, BFSR0, BDR0, BCLKX0, BFSX0, BDX0, INT0, INT1, IACK" of the module are connected to the McBSP0 expansion port.

Claims (7)

1. an encryption method of a high security level symmetric key algorithm is characterized in that the encryption method is: formed by N rounds of encryption rounds in series, and the encryption sequence of each encryption round is row shift transformation (1), S Box substitution column mix transformation (2), subkey modulo 2 plus transformation (3), the final output of each encryption round, that is, subkey modulo 2 plus transformation (3), then the input of the next encryption round is row shift Transform (1), add the data/key to the plaintext (4) and the seed key (5), the result of the data/key addition (6) is sent to the row shift transformation (1) of the 0th round, and the seed Key (5) sends the last transformation of each encryption round through the encryption wheel key _Wi that key diffusion (7) produces respectively, namely the subkey modulo 2 plus transformation (3); the encryption of the encryption round of the last round The sequence is S-box substitution transformation (8), row shift transformation (1), subkey modulo 2 plus transformation (3), and the subkey modulo 2 plus transformation (3) of the last encryption round outputs ciphertext; : Row shift transformation (1) is to carry out cyclic shift operation separately to the byte of each row of the state; S box replacement_column mixed transformation (2) is to rearrange the transformation order of the encryption round of the extension algorithm, put S The order of box substitution and row shifting is reversed, and the S-box substitution transformation is merged into the column mixing transformation; the subkey modulo 2 plus transformation (3) is to add the wheel key modulo 2 obtained by key diffusion to each state in the state Byte; the transformation method of row shift transformation (1) is: the row shift transformation performs a circular shift operation on the bytes of each row of the state separately, and satisfies the following relationship: the 0th row and the 4th row are not shifted; Line 1 and line 5 are shifted by 1 byte; line 2 and line 6 if Nb=4, where Nb is the length of the data block entering the encryption round in the encryption algorithm divided by 64, or Nb=6, Shift 2 bytes, otherwise shift 3 bytes; if Nb=4 or Nb=6 in the 3rd row and the 7th row, shift 3 bytes, otherwise shift 4 bytes; S box replaces_column mixed transformation ( 2) The conversion method is: multiply each byte of the S-box by 02, 03, 04, and 05 modulo m(x) in advance, where m(x)=x ⁸ +1, to form 4 one-dimensionally expanded S-boxes Substitution tables: MUL02, MUL03, MUL04, MUL05. The specific descriptions and limitations of these 4 tables are shown in the following equations: MUL02[·]＝S[·]·02mod m(x) MUL03[·]＝S[·]·03mod m(x) MUL04[·]＝S[·]·04mod m(x) MUL05[·]＝S[·]·05mod m(x) where m(x)=x ⁸ +1 Rearrange the transformation order of the encryption round of the extension algorithm, reverse the order of S-box substitution and row shifting, and merge the S-box substitution transformation into the column mixing transformation; when transforming, first expand the S from each sheet according to the coefficients of the column mixing transformation Find the converted value of each column of the status byte in the box permutation table, and then perform XOR operation on these values to obtain the new value after the entire conversion of a certain byte of the status; and so on, you can get the converted value of other bytes of the status New numerical value; The transformation method of subkey modulo 2 plus transformation (3) is: subkey modulo 2 plus transformation is to add the wheel key modulo 2 obtained by key diffusion to each byte in the state. 2. The encryption method of the high security level symmetric key algorithm according to claim 1, wherein the number of rounds Nr of encryption is jointly determined by Nk and Nb, wherein Nk is the integer obtained by dividing the length of the seed key by 64, and Nb It is the integer obtained by dividing the length of the data block in each encryption round in the encryption algorithm by 64, that is, the value of Nr is equal to the larger value of Nk and Nb plus 6, so that Nr is 10, 12 or 14. 3. according to the encryption method of the described high security level symmetric key algorithm of claim 1, it is characterized in that key diffusion (7) is made up of two processes: 1) Key diffusion: the seed key is diffused into a diffusion key; 2) Selection of the wheel key: ●The subkey used in each round is selected from the diffusion key; ●The word selected each time is 64bits or 8 bytes; The round constant is composed of 8-byte constants, the first 7 bytes of these 8 bytes are 0, the last byte of the first round is 01, and the last byte of the remaining rounds is the round constant of the previous round The last byte is multiplied by '02'. 4. a decryption method of a high security level symmetric key algorithm is characterized in that the decryption method is: it is formed by series connection and combination of N rounds of decryption rounds, and the decryption sequence of each decryption round is subkey modulo 2 plus transformation (3 ), inverse column mixing transformation (9), inverse S-box substitution transformation (10), inverse row shift transformation (11), the final output of each decryption round is the inverse row shift transformation (11), and then the input of the next decryption round is Subkey modulo 2 plus transformation (3), ciphertext (12) and seed key (5) undergo data/key addition (6), and the result of data/key addition (6) is sent to the 0th round The subkey modulo 2 plus transformation (3), and the decryption wheel key W _i generated by the seed key (5) through key diffusion (7) are respectively sent to the first transformation of each decryption round, that is, the subkey modulo 2 Add transformation (3); the decryption order of the last round of decryption round is subkey modulo 2 plus transformation (3), inverse S-box substitution transformation (10), retrograde shift transformation (11), and the last round of decryption round The retrograde shift transformation (11) outputs the plaintext; the transformation method of the subkey modulo 2 plus transformation (3) is: the subkey modulo 2 plus transformation is to add the wheel key modulo 2 obtained by key diffusion to the state Each byte; the inverse shift transformation (11) is the inverse transformation of the row shift transformation (1); the inverse column mixed transformation (9) is the operation of performing column and column operations on the state according to the coefficient of the column mixed inverse transformation Transformation; inverse S-box substitution transformation (10) is the inverse transformation of S-box substitution transformation (8); S-box substitution transformation (8) is a non-linear byte substitution transformation; this transformation uses an S-box, which consists of 256 A one-dimensional table composed of elements, according to the value of each byte of the intermediate result, retrieve the corresponding substitute value in the S box, and retrieve the corresponding substitute value in the S box according to the value of each byte of the intermediate result; the S box is a A reversible permutation table, consisting of two subtransformations: 1. The multiplicative inverse on the finite field GF(2 ⁸ ), the mapping of the element {00} is itself; 2. Affine over the finite field GF(2), as shown in the following equation: b′ _i = b _i b _(i+4)mod8 b _(i+5)mod8 b _(i+6)mod8 b _(i+7)mod8 c _i Wherein, 0≤i<8, b _i is the i-th bit of the converted byte, {c ₇ c ₆ c ₅ c ₄ c ₃ c ₂ c ₁ c ₀ }={63h}={01100011b}. 5. according to the decryption method of the high security grade symmetric key algorithm described in claim 4, it is characterized in that the inverse column mixed transformation (9) transformation method is: do not change the order of 4 transformations of each round, just to inverse column The mixed transformation is modified, and four multiplier tables are prepared in advance: LUT02, LUT03, LUT04, and LUT05. The specific description and limitation of these four tables are shown in the following equations: LUT02[i]=i·02mod m(x) LUT03[i]=i·03mod m(x) LUT04[i]=i·04mod m(x) LUT05[i]=i·05mod m(x) where i=0, 1, 2...255, m(x)=x ⁸ +1 When transforming, first find the value after modular multiplication of each column byte of the state from each multiplier factor table according to the coefficient of the column mixed inverse transformation, and then perform XOR operation on these values to obtain a certain byte of the state after inverse transformation The new value of , and so on, can get the new value of other bytes of the state after transformation. 6. according to the decryption method of the high security grade symmetric key algorithm described in claim 4, it is characterized in that the retrograde shift transformation (11) is the inverse transformation of the row shift transformation (1), and the row shift transformation (1) The transformation method is: the row shift transformation performs a separate circular shift operation on the bytes of each row of the state, and satisfies the following relationship: the 0th row and the 4th row are not shifted; the 1st row and the 5th row are shifted by 1 byte ;If Nb=4 in the 2nd row and the 6th row, Nb is the length of the data block entering the encryption round in the encryption algorithm divided by 64, or Nb=6, shift 2 bytes, otherwise shift 3 bytes ; If Nb=4 or Nb=6 in line 3 and line 7, shift 3 bytes, otherwise shift 4 bytes. 7. A kind of encryption device of high security level symmetric key algorithm, it is characterized in that encryption device is made up of DSP module (13), FLASH module (14), McBSP0 extension port (15), " D15 of DSP module (13) -D0" is connected with the "D15-D0" end of the FLASH module (14), the "A15-A0" of the DSP module (13) is connected with the "A15-A0" end of the FLASH module (14), and the DSP module (13 )'s " MSTRB, R/W " connects the " WE " end of the FLASH module ( 14 ) through the AND gate, and the " MSTRB " of the DSP module ( 13 ) connects the input end of a NOT gate, and this NOT gate output terminal and the DSP module ( 13) " R/W " connects two input ends of a NAND gate respectively, the output terminal of this NAND gate connects the " OE " end of FLASH module (14), " BCLKR0, BFSR0, BCLKR0, BFSR0, BDR0, BCLKX0, BFSX0, BDX0, INT0, INT1, IACK" are connected to the McBSP0 expansion port (15).

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