CN112202547B - A lightweight block cipher GFCS implementation method, device and readable storage medium - Google Patents

Abstract

The invention discloses a method and a device for realizing a lightweight block cipher GFCS and a readable storage medium, wherein the method comprises the following steps: s1: taking a plaintext or ciphertext with the length of L as data to be encrypted or decrypted, and dividing the data into 4 data blocks; acquiring an initial key with the length of L, and dividing the initial key into 4 subblocks, wherein L is a positive integer divided by 4; s2: performing at least N rounds of key expansion round operations on the 4 sub-blocks of the initial key to obtain round keys of the 4 sub-blocks; s3: if the encryption operation is performed, performing N-1 rounds of XOR operation and shift operation by using the round key, the data to be encrypted and the round operation function, and performing a round of XOR operation to obtain a ciphertext; if the data is the decryption operation, firstly carrying out XOR operation once by using the round key, the data to be decrypted and the round operation function, and then carrying out XOR operation and shift operation in the N-1 round to obtain the plaintext. The method of the invention improves the algorithm efficiency while ensuring the safety.

Description

A lightweight block cipher GFCS implementation method, device and readable storage medium

technical field

The invention belongs to the technical field of cryptography, and in particular relates to a method, a device and a readable storage medium for implementing a lightweight block cipher GFCS.

Background technique

With the continuous advancement of the Internet of Things era, various wireless sensors, radio frequency identification tags, smart cards and other embedded devices that occupy less resources, consume less power, and achieve high efficiency have become closely related to people's lives. In the resource-constrained devices with low power storage capacity such as wireless sensors, it is obviously inapplicable and unnecessary to use traditional complex cryptographic algorithms to protect the data in them. Therefore, the design of lightweight block cipher algorithms has been affected by more and more attention.

The design of the lightweight block cipher algorithm needs to reduce the computational cost or computational performance of the algorithm while ensuring certain security, so that it can achieve the effect of low resource consumption and high execution efficiency, which is suitable for software and hardware implementation. On the other hand, the continuous development of cryptanalysis technology also provides more ideas and improvement directions for the design of lightweight block cipher algorithms, which promotes lightweight block cipher algorithms to not only ensure security but also provide better implementation. efficiency. Since the relevant standards for lightweight block cipher algorithms have not been formulated, how to design a lightweight block cipher algorithm with certain security and high implementation efficiency is still an important issue that needs to be studied for a long time in the future.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a brand-new means to realize the encryption and decryption of the lightweight block cipher algorithm, while ensuring the security, improving the efficiency of the algorithm and reducing the resource occupied area of the algorithm.

On the one hand, a light-weight block cipher GFCS implementation method provided by the present invention comprises the following steps:

S1: Take plaintext or ciphertext of length L as the data to be encrypted or decrypted, and divide it into 4 data blocks; and obtain an initial key of length L, and divide the initial key into 4 sub-blocks, L is a positive integer divisible by 4;

S2: perform at least N rounds of key expansion round operations on the 4 sub-blocks of the initial key to obtain the round keys of the 4 sub-blocks;

S3: If it is an encryption operation, use the round key, the data to be encrypted and the round operation function to first perform N-1 rounds of XOR operation and shift operation, and then perform one round of XOR operation to obtain the ciphertext;

If it is a decryption operation, use the round key, the data to be decrypted and the round operation function to perform an XOR operation first, and then perform N-1 rounds of XOR operation and shift operation to obtain the plaintext.

The GFCS block cipher algorithm provided by the present invention is mainly a cipher algorithm based on the generalized Feistel structure. The basic operation components of the algorithm are simple and lightweight, and only consist of general components XOR, logical AND, logical NOT and cyclic shift, and the round function is repeatedly used. The basic component of the key expansion algorithm can further improve the efficiency of hardware implementation.

标记位i的轮密钥

以及下一个标记位的加密数据

或下下一个标记位的加密数据

输入标记位i的F函数F_i的输出结果

或

进行异或运算作为按移位顺序的下一个标记位在下一轮的加密数据

其中，若下一个标记位的加密数据是下一个标记位在下一轮的加密数据，则选择下下个标记位的加密数据输入至标记位i的F函数中，其中，四个数据块中对应存在三个F函数与同一识别标记的轮密钥对应的轮运算函数f为同一函数，存在一个F函数满足：F(x)＝x。In the first N-1 rounds of XOR operation and shift operation of the encryption operation, for each data block in the rth round, according to the shift order, the encrypted data of the marked bit i is

round key for bit i

and the encrypted data for the next flag bit

or the encrypted data of the next flag bit

The output result of the F function F _i with the input flag i

or

XOR operation is performed as the encrypted data in the next round of the next mark bit in the shift order

Among them, if the encrypted data of the next marker bit is the encrypted data of the next marker bit in the next round, then select the encrypted data of the next marker bit and input it into the F function of the marker bit i, wherein the corresponding There are three F functions and the round operation function f corresponding to the round key of the same identification mark is the same function, and there is one F function satisfying: F(x)=x.

标记位i的轮密钥

以及下一个标记位的加密数据

输入标记位i的F函数F_i的输出结果

进行异或运算得到密文。In the last round of XOR operation, the encrypted data of bit i will be marked

round key for bit i

and the encrypted data for the next flag bit

The output result of the F function F _i with the input flag i

Perform an exclusive OR operation to obtain the ciphertext.

The decryption process corresponds to the encryption process. The shift order in the decryption process is exactly the opposite of the encryption process. The F function also corresponds to one-to-one. The keys participate in the N rounds of decryption in turn.

Optionally, if it is an encryption operation, the calculation formulas corresponding to the first N-1 rounds of XOR operation and shift operation of the four data blocks of the data to be encrypted are as follows:

表示第r+1轮密钥扩展轮运算中得到的识别标记a对应的轮密钥；F_a、F_b、F_c、F_d存在三个公式中F函数与同一识别标记的轮密钥对应的轮运算函数f为同一函数，存在一个公式中的F函数满足：F(x)＝x。Among them, the subscripts a, b, c, and d are the data block identification marks set sequentially in the encryption process according to the shift sequence in the shift operation, X represents the encrypted data, and the superscript r represents the number of rounds.

Indicates the round key corresponding to the identification mark a obtained in the r+1th round of key expansion round operation; F _a , F _b , F _c , and F _d exist in three formulas in which the F function corresponds to the round key of the same identification mark The round operation function f of is the same function, and the F function in a formula satisfies: F(x)=x.

Optionally, if it is an encryption operation, the formula for the N-th XOR operation of the four data blocks of the data to be encrypted is as follows:

初始密钥K分也划分为4个子块，K＝(k₀,k₁,k₂,k₃)，针对各个子块设置了轮函数f_i＝f，(i＝0,1,2,3)，本发明在加密过程中，针对明文P的4个数据块的移位顺序可以是按照0→1→2→3→0的顺序依次进行移位，还可以针对4个数据块以其他顺序进行移位，譬如0→1→3→2→0，本发明对此不进行具体的限定，为了保护各种移位顺序，本发明按照移位顺序将4个数据块进行了标记，标记为a、b、c、d，对应设置的移位顺序为：a→b→c→d→a；于此同时，上述F_a、F_b、F_c、F_d中存在三个函数与f₀、f₁、f₂、f₃对应一致，存在一个函数满足：F(x)＝x，具体哪一个本发明对此不进行限定。If the encryption operation is performed, the plaintext P of length L is divided into 4 data blocks,

The initial key K is also divided into 4 sub-blocks, K=(k ₀ , k ₁ , k ₂ , k ₃ ), and the round function f _i =f is set for each sub-block, (i=0,1,2, 3), in the encryption process of the present invention, the shift sequence for the 4 data blocks of the plaintext P may be shifted in the order of 0→1→2→3→0, or the 4 data blocks may be shifted by other Shift in sequence, such as 0→1→3→2→0, which is not specifically limited in the present invention. In order to protect various shift sequences, the present invention marks 4 data blocks according to the shift sequence. are a, b, c, and d, and the corresponding shift order is: a→b→c→d→a; at the same time, there are three functions in the above F _a , F _b , F _c , and F _d and f ₀ , f ₁ , f ₂ , and f ₃ correspond to the same, and there is a function that satisfies: F(x)=x, which is not limited in the present invention.

进行第一次异或运算的公式如下：Optionally, if it is a decryption operation, for the ciphertext

The formula to perform the first XOR operation is as follows:

表示密文C中数据块识别标记d对应在第一次异或运算的解密结果，上标N表示轮数，

表示第N轮密钥扩展轮运算中得到的识别标记a对应的轮密钥；F_a、F_b、F_c、F_d均为设置的F函数，且在三个公式中F函数与同一识别标记的轮密钥对应的轮运算函数f为同一函数，剩余一个公式中的F函数满足：F(x)＝x。In the formula, the subscripts d, c, b, and a are the data block identification marks set sequentially in the decryption process according to the shift sequence in the shift operation, Y represents the decrypted data,

Indicates that the data block identification mark d in the ciphertext C corresponds to the decryption result of the first XOR operation, and the superscript N represents the number of rounds,

Indicates the round key corresponding to the identification mark a obtained in the Nth round of key expansion round operation; F _a , F _b , F _c , and F _d are all set F functions, and in the three formulas, the F function is the same as the same identification The round operation function f corresponding to the marked round key is the same function, and the F function in the remaining formula satisfies: F(x)=x.

Similarly, the shift sequence of the decryption process is just opposite to that of the encryption process. The shift sequence of the decryption process of the present invention is: d→c→b→a→d, so the same identification mark in the encryption process and the decryption process represents the same data block. Similarly, there are three functions in the above F _a , F _b , F _c , and F _d that correspond to f ₀ , f ₁ , f ₂ , and f ₃ , and there is a function that satisfies: F(x)=x, in this process There is a one-to-one correspondence with the encryption process.

Optionally, in the process of performing N-1 rounds of XOR operation and shift operation on ciphertext C to obtain plaintext, the formula for each round of XOR operation and shift operation is as follows:

其中，

表示第r轮的轮密钥的四个子块，f₀,f₁,f₂,f₃表示四个子块分别对应的轮函数f，其中，轮函数记为：Optionally, the four sub-blocks k ₀ , k ₁ , k ₂ , and k ₃ of the initial key K in step S2 correspond to N rounds of key expansion round operations, and the round key K ^r of the rth round is recorded as:

in,

Represents the four sub-blocks of the round key of the rth round, f ₀ , f ₁ , f ₂ , f ₃ represent the round function f corresponding to the four sub-blocks respectively, where the round function is denoted as:

f: (x ₀ , x ₁ , x ₂ , x ₃ )→(y ₀ , y ₁ , y ₂ , y ₃ )

In the formula, x ₀ , x ₁ , x ₂ , and x ₃ respectively represent the four sub-block data of the input round function f, and y ₀ , y ₁ , y ₂ , and y ₃ respectively represent the corresponding output data, and satisfy:

The algorithm adds logical AND and logical NOT operations to the round function to further improve the confusion of the algorithm, and the round function reuses the basic components of the key expansion algorithm, which can further improve the hardware implementation efficiency.

Optionally, if L is 128, the corresponding length of each data block is 32; if L is 64, the corresponding length of each data block is 16; if L is 256, the corresponding length of each data block is 64.

In a second aspect, the present invention also provides a device based on the above implementation method, comprising:

Data loading module: used to obtain the plaintext or ciphertext of length L, and to obtain the initial key of length L,

Round key generation module: used to perform at least N rounds of key expansion round operations on the 4 sub-blocks of the initial key to obtain the round keys of the 4 sub-blocks

Encryption and decryption module: When used for encryption operation, use the round key, the data to be encrypted and the round operation function to perform N-1 rounds of XOR operation and shift operation, and then perform one round of XOR operation to obtain the ciphertext; or for decryption During the operation, use the round key, the data to be decrypted and the round operation function to perform an XOR operation first, and then perform N-1 rounds of XOR operation and shift operation to obtain the plaintext.

In a third aspect, the present invention further provides an apparatus comprising a memory and a processor, wherein the memory stores a computer program, and the processor invokes the computer program to execute the steps of the method for implementing the lightweight block cipher GFCS.

In a fourth aspect, the present invention further provides a readable storage medium storing a computer program, the computer program being invoked by a processor to execute the steps of the method for implementing the lightweight block cipher GFCS.

beneficial effect

The method provided by the present invention only utilizes simple XOR operation and cyclic shift operation, and has good confusion and diffusion capability, so that this lightweight block cipher can further save hardware resources while ensuring certain security , the realization efficiency is improved, and the safety and efficiency of the present invention are also verified through experiments.

Description of drawings

FIG. 1 is a schematic structural diagram of a method for implementing a lightweight block cipher GFCS provided by an embodiment of the present invention.

Detailed ways

的移位顺序可以是按照0→1→2→3→0的顺序依次进行移位为例进行说明，下面将结合实施例对本发明做进一步的说明。The purpose of the light-weight block cipher GFCS implementation method provided by the present invention is to further reduce the resource occupation area of the algorithm and improve the implementation efficiency while ensuring the security of the block cipher. In this embodiment, four data blocks of plaintext P are used

The shift sequence of , can be described by taking the sequence of 0→1→2→3→0 as an example for description, and the present invention will be further described below with reference to the embodiments.

The method described in this embodiment includes:

Step 1: Load the 128-bit plaintext/ciphertext and the 128-bit key into the register as data to be encrypted/decrypted.

Step 2: Extend the 128-bit initial key to N rounds of key expansion algorithms into N round keys with a length of 128 bits. The key expansion algorithm is as follows:

其中4个函数分别表示为f_i＝f<<<a_i(i＝0,1,2,3；a_i＝1,7,11,2)是一组基于异或运算，非运算，与运算和循环移位运算的函数，其中f是作用于输入为32比特的函数，<<<为循环左移运算，记为：f:(x₀，x₁，x₂，x₃)→(y₀，y₁，y₂，y₃),存在：Divide the initial key K into four 32-bit sub-blocks, namely K=(k ₀ , k ₁ , k ₂ , k ₃ ), and the input of the round key of the rth round is denoted as

The four functions are respectively expressed as f _i =f<<<a _i (i=0,1,2,3; a _i =1,7,11,2) is a group based on XOR operation, NOT operation, and The function of operation and cyclic shift operation, where f is the function that acts on the input of 32 bits, <<< is the cyclic left shift operation, denoted as: f:(x ₀ , x ₁ , x ₂ , x ₃ )→( y ₀ , y ₁ , y ₂ , y ₃ ), exist:

～、&分别表示异或运算，非运算，与运算。where r is the current round number,

~ and & represent XOR, NOT, and AND respectively.

Step 3: If it is an encryption operation, the encryption process is:

首先重复执行下列操作N-1次：Divide the input plaintext P into 4 sub-blocks of length 32 bits, namely

First repeat the following N-1 times:

where r is the current round number, f _i (i=0,1,2) is the same as the first three functions in the key expansion algorithm; then perform the following operations once:

The final output ciphertext

If it is a decryption operation, the decryption process is:

首先，执行下列操作1次：Divide the input ciphertext C into 4 sub-blocks of length 32 bits, namely

First, do the following 1 time:

Then, repeat the following operations N-1 times:

Among them, r is the current round number, and f _i (i=0, 1, 2) is the same as the first three functions in the key expansion algorithm. final output plaintext

It should be understood that in the above embodiment, the plaintext length or the ciphertext length 128 is used as an example, and the present invention is not limited to this embodiment; and in this embodiment, the F3 function satisfies: F(x) ₌ x. The other F ₀ , F ₁ , and F ₂ correspond to f ₀ , f ₁ , and f ₂ respectively, but the present invention is not limited to this embodiment.

In some feasible solutions, the present invention provides a device based on the above-mentioned lightweight block cipher GFCS implementation method, including:

Data loading module: used to obtain the plaintext or ciphertext of length L, and to obtain the initial key of length L,

Round key generation module: used to perform at least N rounds of key expansion round operations on the 4 sub-blocks of the initial key to obtain the round keys of the 4 sub-blocks

Encryption and decryption module: When used for encryption operation, use the round key, the data to be encrypted and the round operation function to perform N-1 rounds of XOR operation and shift operation, and then perform one round of XOR operation to obtain the ciphertext; or for decryption During the operation, use the round key, the data to be decrypted and the round operation function to perform an XOR operation first, and then perform N-1 rounds of XOR operation and shift operation to obtain the plaintext.

For the specific implementation process of each module, please refer to the content of the above method, which will not be repeated here. It should be understood that the division of the above functional modules is only a division of logical functions, and other division methods may be used in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored. or not. Meanwhile, the above-mentioned integrated units may be implemented in the form of hardware, and may also be implemented in the form of software functional units.

In some feasible solutions, the present invention also provides an apparatus including a memory and a processor, the memory stores a computer program, and the processor invokes the computer program to execute the lightweight block cipher GFCS implementation method A step of.

In some feasible solutions, the present invention also provides a readable storage medium storing a computer program, the computer program being invoked by a processor to execute the steps of the method for implementing the lightweight block cipher GFCS.

The specific implementation process may also refer to the content of the above method. It should be understood that, in this embodiment of the present invention, the processor may be a central processing unit (Central Processing Unit, CPU), and the processor may also be other general-purpose processors, digital signal processors (Digital Signal Processor, DSP), Application Specific Integrated Circuit (ASIC), Field-Programmable Gate Array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, and the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The memory, which may include read-only memory and random access memory, provides instructions and data to the processor. A portion of the memory may also include non-volatile random access memory. For example, the memory may also store device type information.

The readable storage medium is a computer-readable storage medium, which may be an internal storage unit of the controller described in any of the foregoing embodiments, such as a hard disk or a memory of the controller. The readable storage medium may also be an external storage device of the controller, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) equipped on the controller card, flash card (Flash Card) and so on. Further, the readable storage medium may also include both an internal storage unit of the controller and an external storage device. The readable storage medium is used to store the computer program and other programs and data required by the controller. The readable storage medium can also be used to temporarily store data that has been output or is to be output.

Experimental verification:

The test data of the GFCS-128 algorithm iteration of the present invention for 40 rounds are shown in Table 1:

Table 1 GFCS algorithm test data

The GFCS cryptographic algorithm of the present invention is implemented in hardware in ASIC and synthesized in Synopsys DesignCompiler Version B-2008.09, wherein the integrated process library is SMIC 0.18um, and in the comprehensive experiment, the area resource unit is 1622GE. The resource area occupied by the GFCS-128 algorithm is 1622GE. The implementation area comparison of each lightweight block cipher algorithm is shown in Table 2.

Table 2 Comparison of the implementation area of each lightweight block cipher algorithm

It should be emphasized that the examples described in the present invention are illustrative rather than restrictive, so the present invention is not limited to the examples described in the specific implementation manner, and all those obtained by those skilled in the art according to the technical solutions of the present invention Other embodiments that do not depart from the spirit and scope of the present invention, whether modified or replaced, also belong to the protection scope of the present invention.

Claims (10)

1. a lightweight block cipher GFCS implementation method, is characterized in that: comprise the steps: S1: Take plaintext or ciphertext of length L as the data to be encrypted or decrypted, and divide it into 4 data blocks; and obtain an initial key of length L, and divide the initial key into 4 sub-blocks, L is a positive integer divisible by 4; S2: perform at least N rounds of key expansion round operations on the 4 sub-blocks of the initial key to obtain the round keys of the 4 sub-blocks; S3: If it is an encryption operation, use the round key, the data to be encrypted and the round operation function to first perform N-1 rounds of XOR operation and shift operation, and then perform one round of XOR operation to obtain the ciphertext; If it is a decryption operation, use the round key, the data to be decrypted and the round operation function to perform an XOR operation first, and then perform N-1 rounds of XOR operation and shift operation to obtain the plaintext; Among them, in the first N-1 rounds of XOR operation and shift operation of the encryption operation, for each data block in the rth round, according to the shift order, the encrypted data of the marked bit i is

round key for bit i

and the encrypted data for the next flag bit

or the encrypted data of the next flag bit

The output result of the F function F _i with the input flag i

or

XOR operation is performed as the encrypted data in the next round of the next mark bit in the shift order

Among them, if the encrypted data of the next marker bit is the encrypted data of the next marker bit in the next round, then select the encrypted data of the next marker bit and input it into the F function of the marker bit i, wherein, the three F functions and the round Any three of the round operation functions f _i (i=0, 1, 2, 3) corresponding to the key are the same function, and there is an F function that satisfies: F(x)=x; The decryption process corresponds to the encryption process. The shift order in the decryption process is exactly the opposite of the encryption process. The F function corresponds one-to-one. The use of the round key is the round obtained from the Nth round key expansion to the first round key expansion. The keys participate in the N rounds of decryption in turn. 2. method according to claim 1, is characterized in that: if it is encryption operation, 4 data blocks of the data to be encrypted are as follows in front N-1 round XOR operation and the corresponding calculation formula of shift operation:

Among them, the subscripts a, b, c, and d are the data block identification marks set sequentially in the encryption process according to the shift sequence in the shift operation, X represents the encrypted data, and the superscript r represents the number of rounds.

Indicates the round key corresponding to the identification mark a obtained in the r+1th round of key expansion round operation; F _a , F _b , F _c , and F _d are all set F functions. 3. method according to claim 2 is characterized in that: if it is encryption operation, the formula of 4 data blocks of data to be encrypted is as follows in the Nth round XOR operation:

4. method according to claim 1 is characterized in that: if it is decryption operation, for ciphertext

The formula to perform the first XOR operation is as follows:

In the formula, the subscripts d, c, b, and a are the data block identification marks set sequentially in the decryption process according to the shift sequence in the shift operation, Y represents the decrypted data,

Indicates that the data block identification mark d in the ciphertext C corresponds to the decryption result of the first XOR operation, and the superscript N represents the number of rounds,

Indicates the round key corresponding to the identification mark a obtained in the Nth round of key expansion round operation; F _a , F _b , F _c , and F _d are all set F functions. 5. method according to claim 4, is characterized in that: carry out N-1 round XOR operation and shift operation to obtain the process of plaintext for ciphertext C, each round XOR operation and shift operation formula are as follows:

6. The method according to claim 2, characterized in that: in step S2, the 4 sub-blocks k ₀ , k ₁ , k ₂ , and k ₃ of the initial key K correspond to N rounds of key expansion round operations, and the rth The round key K ^r of the round is denoted as:

in,

Represents the four sub-blocks of the round key K ^r of the rth round, f ₀ , f ₁ , f ₂ , f ₃ represent the four functions corresponding to the four sub-blocks, respectively expressed as f _i =f<<<a _i (i= 0,1,2,3; a _i =1,7,11,2), where f is recorded as: f: (x ₀ , x ₁ , x ₂ , x ₃ )→(y ₀ , y ₁ , y ₂ , y ₃ ) In the formula, x ₀ , x ₁ , x ₂ , and x ₃ respectively represent the four sub-block data of the input round function f, and y ₀ , y ₁ , y ₂ , and y ₃ respectively represent the corresponding output data, and satisfy:

in,

~ and & represent XOR, NOT, and AND respectively. 7. The method according to claim 1, wherein: if L is 128, the length corresponding to each data block is 32; if L is 64, the length corresponding to each data block is 16; if L is 256, The length corresponding to each data block is 64. 8. A device based on the method of any one of claims 1-7, characterized in that: comprising: Data loading module: used to obtain the plaintext or ciphertext of length L, and to obtain the initial key of length L, Round key generation module: used to perform at least N rounds of key expansion round operations on the 4 sub-blocks of the initial key to obtain the round keys of the 4 sub-blocks Encryption and decryption module: When used for encryption operation, use the round key, the data to be encrypted and the round operation function to perform N-1 rounds of XOR operation and shift operation, and then perform one round of XOR operation to obtain the ciphertext; or for decryption During the operation, use the round key, the data to be decrypted and the round operation function to perform an XOR operation first, and then perform N-1 rounds of XOR operation and shift operation to obtain the plaintext. 9. An apparatus, characterized by comprising a memory and a processor, wherein the memory stores a computer program, and the processor invokes the computer program to execute the steps of the method of any one of claims 1-7. 10. A computer-readable storage medium, characterized in that: a computer program is stored, and the computer program is invoked by a processor to execute the steps of the method of any one of claims 1-7.

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