A suitability evaluation method for symmetric cryptography technology suitable for embedded systems

Abstract

The present invention relates to a method for evaluating the adaptability of a symmetric cryptographic technology suitable for an embedded system, and belongs to the field of industrial control. The method comprises the following steps: giving a definition of adaptability; constructing an adaptability evaluation index system; determining a weight coefficient of an adaptability evaluation index; quantifying an eigenvalue of an adaptability evaluation index; forming a fuzzy multi-level adaptability evaluation model based on AHP and applying the model to obtain an adaptability evaluation result of a cryptographic technology and an embedded system; and providing a corresponding relationship between an adaptability evaluation result and an adaptability definition. The method adopts multi-faceted evaluation criteria to evaluate the adaptability of a cryptographic algorithm and an embedded system. When quantifying the eigenvalue, an algorithm benchmark is introduced. Taking the performance of AES‑GCM as a benchmark, an adaptability evaluation model for a symmetric cryptographic technology for an embedded system is constructed, and the adaptability of a cryptographic algorithm and an embedded system can be more accurately evaluated.

Description

Technical Field

[0001] The invention belongs to the field of industrial control and relates to an adaptability evaluation method of a symmetric cryptographic technology suitable for an embedded system. Background Art

[0002] Industrial control systems are widely used in many fields of national critical infrastructure, including electricity, energy, transportation, and petrochemicals. With the rapid development of information technology, the integration of industrial systems and information technology is also deepening. Embedded devices have become a major component of industrial control systems, and due to their special hardware and software architecture, they are usually vulnerable to attacks. Therefore, the security issues of industrial control systems have attracted more and more attention, especially the security issues of embedded devices in them.

[0003] Embedded devices usually use real-time operating systems (RTOS) for task scheduling to improve resource utilization. These embedded real-time systems have simple and limited resources, such as power, computing, and communication, and require low cost and deployment in harsh environments. These characteristics make the security requirements of embedded systems more stringent, far exceeding traditional computer systems. Therefore, ensuring the security of embedded systems has become a more important and challenging goal.

[0004] Embedded systems have high requirements for real-time performance, so when using cryptographic technology to implement security protection, it may affect the real-time performance of the system or cause additional overhead that the system cannot bear. Generally speaking, the cryptographic structure and key scheduling of cryptographic technologies with higher security will be more complex, thus having a greater actual impact on real-time systems. Traditional cryptographic algorithms with more complex structures may no longer be suitable for embedded systems. In order to provide appropriate security protection for embedded systems, lightweight cryptographic technology has emerged. Even for lightweight cryptographic technology, its effectiveness and adaptability in embedded systems need to be considered. Therefore, it is necessary to consider the security feasibility and effectiveness of lightweight cryptographic technology itself, and at the same time, it is also necessary to consider the extent to which important indicators such as the real-time performance and performance of the target system are affected by lightweight cryptographic technology.

[0005] Therefore, it is very important to propose a compatibility evaluation method for symmetric cryptographic technology suitable for embedded systems, which can evaluate the compatibility of a certain cryptographic technology with embedded systems and better protect the security of embedded systems. Summary of the invention

[0006] In view of this, the purpose of the present invention is to provide a compatibility evaluation method for symmetric cryptographic technology suitable for embedded systems. This method evaluates the compatibility of cryptographic technology with the target carrier embedded system based on the proposed AHP fuzzy multi-level adaptability evaluation model. The cryptographic technology used in this aspect mainly focuses on lightweight cryptographic algorithms.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A method for evaluating the suitability of a symmetric cryptographic technology for an embedded system, the method comprising the following steps:

[0009] Step 1: Give a definition of adaptability. The adaptability of cryptographic technology to embedded systems refers to the applicability of cryptographic technology in embedded systems, which depends on the requirements of the target carrier system. Different carrier systems have different requirements and different adaptability performances. According to the different target carrier systems, give a definition of adaptability applicable to this target carrier system.

[0010] Step 2: Construct an adaptability evaluation index system. Construct a three-layer comprehensive adaptability evaluation index system. To evaluate the adaptability of cryptographic technology and embedded systems, we need to comprehensively evaluate the security performance of cryptographic technology and the performance of cryptographic technology in the target system. Therefore, it includes two evaluation criteria: security and performance. Each evaluation criterion has multiple evaluation indicators, which together constitute the adaptability evaluation index system.

[0011] Step 3: Determine the weight coefficient of the adaptability evaluation index. Comprehensively evaluate the adaptability of cryptographic technology and embedded systems. Different evaluation indicators have different effects on embedded systems in practical applications. Determine the weight coefficient of the evaluation index to reflect the impact of each indicator in practical applications.

[0012] Step 4: Quantify the characteristic values ​​of the adaptability evaluation indicators. Using the fuzzy evaluation method, the qualitative evaluation can be converted into a quantitative evaluation according to the membership theory of fuzzy mathematics. The performance intervals of different evaluation indicators are inconsistent. The characteristic values ​​of the evaluation indicators are quantified to the same interval according to the membership function to evaluate the adaptability of cryptographic technology and embedded systems.

[0013] Step 5: Form a fuzzy multi-level adaptability evaluation model based on AHP and evaluate the adaptability performance of cryptographic technology and embedded systems. Steps 2, 3, and 4 constitute a fuzzy multi-level adaptability evaluation model based on AHP. The weight coefficient matrix and the eigenvalue matrix are multiplied to obtain the fuzzy comprehensive evaluation result. This result is used as a row of the higher-level evaluation result. Repeat step 5 to obtain the fuzzy comprehensive evaluation results of multiple cryptographic algorithms on multiple evaluation criteria.

[0014] Step 6: Give the corresponding relationship between the adaptability evaluation result and the adaptability definition, and obtain the adaptability of the applied cryptographic technology and the target carrier system.

[0015] Optionally, in step 1, adaptability has two limitations: one is that the cryptographic algorithm being evaluated is limited to symmetric cryptographic technology; the other is the target carrier system, and the acceptable performance limits for different carrier systems are also different. A cryptographic algorithm with good adaptability needs to have sufficient security, fast execution speed and small resource usage. Different carrier systems have different requirements, and an adaptation benchmark is set to give a definition of adaptability, including the cryptographic algorithms currently used in embedded systems as benchmarks.

[0016]

[0017] Among them, S A 、V A 、M A They represent the security level, execution efficiency and resource usage of cryptographic algorithm A in a specific embedded system, respectively. I For the required security level of this embedded system, V R 、M R They represent the execution efficiency and resource usage of the cryptographic algorithm used as the benchmark in this specific embedded system. 1 means that the cryptographic algorithm is fully compatible with the embedded system, α means that the cryptographic algorithm is not very compatible with the embedded system in some aspects, but can still be used in specific scenarios, and 0 means it is completely unsuitable.

[0018] Optionally, in step 2, a three-layer comprehensive adaptability evaluation index system is constructed, wherein the first layer is the comprehensive adaptability evaluation result (A), the second layer is the safety standard (B1) and the performance standard (B2), and the third layer is the specific evaluation index, which are respectively the randomness performance under the safety standard (C 11 ), linear attack resistance (C 12 ) and differential attack resistance (C 13 ), the time cost under the performance standard (C 21 ), code size (C 22 )、Flash occupancy(C 23 )、RAM occupancy(C 24 ), CPU usage (C 25 ) and throughput (C 26 ).

[0019] Randomness is reflected by the results of fifteen typical randomness test methods for cryptographic algorithms, including frequency test, group frequency test, run test, maximum 1 run test, binary matrix rank test, discrete Fourier transform test, non-overlapping match test, overlapping match test, global universal test, linear complexity test, serial test, approximate entropy test, cumulative sum test, randomness offset test, and randomness offset test variant. The test results are all expressed in P-Value. Only P-Value ≥ 0.01 indicates that the algorithm has passed this test. It is proposed to use randomness (RT) to represent the randomness performance of the cryptographic algorithm: RT = (F*(FB+R+LRB+BMR+DFT+NoTM+OTM+MU+LC+S+AE+CS+RE+REV)) / 14

[0020] Among them, the right side shows the symbols of fifteen test methods. F represents the result of frequency test, which is the basis of all randomness tests and is represented by 0 or 1. F and other randomness tests are multiplicative, that is, only when the frequency test passes, other randomness tests are meaningful. The degree of randomness of an algorithm depends on the pass rate of the other test methods. The other fourteen test methods are additive.

[0021] The ability to resist linear attacks and differential attacks is determined by analyzing the S-box of the cryptographic algorithm, where the maximum linear deviation of the S-box is used to represent the ability to resist linear attacks. The greater the deviation of the linear expression, the weaker the ability to resist linear attacks, which is represented by S-AL. The maximum differential probability of the S-box is used to represent the ability to resist differential attacks. The greater the differential probability, the weaker the ability to resist differential attacks, which is represented by S-AD.

[0022] There are multiple evaluation indicators under the performance standard, and six indicators are used for evaluation, namely time overhead, code size, Flash occupancy, RAM occupancy, CPU occupancy and throughput.

[0023] The indicator system meets the three aspects of adaptability mentioned in the adaptability definition, namely security, execution speed and resource usage.

[0024] Optionally, in step 3, the analytic hierarchy process AHP is used to determine the weights of the evaluation indicators, which requires four steps: ① scale determination and construction of judgment matrix; ② eigenvector, eigenroot and weight calculation; ③ consistency test analysis; ④ analysis conclusion.

[0025] Optionally, in step 4, the characteristic values ​​of different evaluation indicators are different, so the required membership functions are also different. This method uses a combination of existing objective scale method and assignment method to determine the membership functions of different indicators based on the indicators of existing cryptographic algorithms and linear distribution methods.

[0026] Optionally, in step 5, it is assumed that the set of cryptographic algorithms to be evaluated is E={E1, E2, ..., E m}, evaluation criteria set O = {O1, O2, ..., O i}, assuming that each evaluation criterion O i There are i evaluation index, for E in set E j For example, using vector Indicates n i The characteristic value of the evaluation index is shown in the following formula.

[0027]

[0028] The eigenvalues ​​of the M lightweight cryptographic algorithm evaluation indicators are expressed in the following matrix:

[0029]

[0030] The eigenvalue matrix is ​​then transformed into the following membership level matrix using the membership function:

[0031]

[0032] in

[0033] Assume that n i The weight coefficient set of the evaluation indicators is expressed by the following formula:

[0034]

[0035] in Represents the weight coefficient of each evaluation indicator,

[0036]

[0037] The above formula represents the result of each evaluation criterion, where Represents cryptographic algorithm E j In the evaluation criteria O i The fuzzy comprehensive evaluation results on the above are used as the rows of the higher-level evaluation results, and the above steps are repeated to finally obtain the fuzzy comprehensive evaluation results of multiple cryptographic algorithms on multiple evaluation criteria.

[0038] Optionally, in step 6, the correspondence between the adaptability evaluation result and the adaptability definition is as follows:

[0039]

[0040] Among them, EP ARepresents the evaluation result of cryptographic algorithm A obtained using the adaptability evaluation model proposed in step 5.

[0041] The beneficial effects of the present invention are:

[0042] (1) To make up for the singleness of the evaluation indicators of traditional cryptographic algorithms, it is more convincing to evaluate the adaptability of cryptographic algorithms from multiple aspects.

[0043] (2) When quantizing the eigenvalues, a benchmark algorithm is introduced to more clearly demonstrate the compatibility of the cryptographic algorithm with the embedded system.

[0044] (3) An adaptability evaluation model for symmetric cryptographic technology for embedded systems was constructed to more accurately evaluate the adaptability of cryptographic algorithms to embedded systems.

[0045] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0047] Figure 1 Represents the basic framework of the adaptability evaluation model;

[0048] Figure 2 It represents a three-layer comprehensive adaptability evaluation index system;

[0049] Figure 3 A flowchart showing the adaptability evaluation method is shown in FIG. DETAILED DESCRIPTION

[0050] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and the features in the embodiments can be combined with each other without conflict.

[0051] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0052] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "back" and the like indicate directions or positional relationships, they are based on the directions or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0053] Figure 1 Represents the basic framework of the adaptability evaluation model; Figure 2 It represents a three-layer comprehensive adaptability evaluation index system; Figure 3 The present invention is generally divided into 6 steps to establish a method for evaluating the adaptability of symmetric cryptographic technology suitable for embedded systems. Figure 2 As shown in the figure, an example of the suitability evaluation of a specific cryptographic algorithm and an embedded system is introduced:

[0054] Step 1: Give a definition of adaptability. The adaptability of cryptographic technology to embedded systems refers to the applicability of cryptographic technology in embedded systems, which depends on the requirements of the target carrier system. Different carrier systems have different requirements and different adaptability performances. According to the different target carrier systems, give a definition of adaptability applicable to this target carrier system.

[0055] Step 2: Construct an adaptability evaluation index system. Construct a three-layer comprehensive adaptability evaluation index system. To evaluate the adaptability of cryptographic technology and embedded systems, we need to comprehensively evaluate the security performance of cryptographic technology and the performance of cryptographic technology in the target system. Therefore, it includes two evaluation criteria: security and performance. Each evaluation criterion has multiple evaluation indicators, which together constitute the adaptability evaluation index system.

[0056] Step 3: Determine the weight coefficient of the adaptability evaluation index. Comprehensively evaluate the adaptability of cryptographic technology and embedded systems. Different evaluation indicators have different effects on embedded systems in practical applications. Therefore, it is necessary to determine the weight coefficient of the evaluation index to show the impact of each indicator in practical applications as much as possible.

[0057] Step 4: Quantify the characteristic values ​​of the adaptability evaluation indicators. Using the fuzzy evaluation method, the qualitative evaluation can be converted into a quantitative evaluation according to the membership theory of fuzzy mathematics. Since the performance intervals of different evaluation indicators are inconsistent, the characteristic values ​​of the evaluation indicators should be quantified to the same interval according to the membership function, which is more convenient and intuitive to evaluate the adaptability of cryptographic technology and embedded systems.

[0058] Step 5: Form a fuzzy multi-level adaptability evaluation model based on AHP and evaluate the adaptability performance of cryptographic technology and embedded systems. Steps 2, 3, and 4 constitute a fuzzy multi-level adaptability evaluation model based on AHP. The weight coefficient matrix and the eigenvalue matrix are multiplied to obtain the fuzzy comprehensive evaluation result. This result is used as a row of the higher-level evaluation result. Repeating this step can obtain the fuzzy comprehensive evaluation results of multiple cryptographic algorithms on multiple evaluation criteria.

[0059] Step 6: Give the corresponding relationship between the adaptability evaluation result and the adaptability definition. The adaptability of the applied cryptographic technology and the target carrier system can be obtained.

[0060] Before taking the first step, it is necessary to determine the cryptographic algorithms and embedded system experimental platforms that need to be evaluated, and to set AES-GCM as the benchmark.

[0061] Step 1: Adaptability definition. Assume that the cryptographic algorithm is A and its security level in an embedded system is S. A , the execution efficiency is V A , the resource usage is M A , the security level required for this embedded system is s1, and the execution efficiency of AES-GCM in the same embedded system is V R , the resource usage is M R , then the adaptability of algorithm A in embedded systems can be defined as:

[0062]

[0063] Where S A The security capability of cryptographic algorithm A can be reflected by randomness and anti-attack capability. A It indicates the execution efficiency of the cryptographic algorithm, which can be reflected by time cost and throughput. A Indicates the resource usage of the cryptographic algorithm, which can be reflected by memory usage and CPU usage. 1 means that the cryptographic algorithm is fully compatible with the embedded system, α means that the cryptographic algorithm is not compatible with the embedded system in some aspects, but can still be used in specific scenarios, and 0 means it is completely incompatible.

[0064] Step 2: Construct an adaptability evaluation index system. Construct a three-layer comprehensive adaptability evaluation index system. The first layer is the comprehensive evaluation results (A), the second layer is the safety standard (B1) and the performance standard (B2), and the third layer is the specific evaluation indicators, which are the random performance under the safety standard (C 11 ), linear attack resistance (C 12 ) and differential attack resistance (C 13 ), the time cost under the performance standard (C 21 ), code size (C 22 )、Flash occupancy(C 23 )、RAM occupancy(C 24 ), CPU usage (C 25 ) and throughput (C 26 ).

[0065] There can be multiple evaluation indicators under the performance standard. This method uses six common indicators for evaluation, namely time overhead, code size, Flash occupancy, RAM occupancy, CPU occupancy and throughput.

[0066] This indicator system meets the three aspects of adaptability mentioned in the adaptability definition, namely security, execution speed and resource usage.

[0067] Step 3: Determine the weight coefficient of the adaptability evaluation index. Comprehensively evaluate the adaptability of a cryptographic technology to an embedded system. Different evaluation indicators have different impacts on the results and even on the embedded system in actual applications. Therefore, it is necessary to determine the weight coefficient of the evaluation index. Use the AHP method to determine the weight of the evaluation index. Here we only give the specific weight of each indicator. The cryptographic algorithm has the same requirements for resisting linear attacks and differential attacks, so and The same, and the Flash and RAM of the cryptographic algorithm are smaller than the space of the selected experimental platform, so the proportion is low and the same.

[0068] Before quantifying the eigenvalues, it is necessary to measure the original eigenvalues ​​of the indicators used in the cryptographic algorithm in the embedded system.

[0069] Step 4: Quantify the characteristic values ​​of the adaptability evaluation indicators. This method uses a fuzzy evaluation method based on fuzzy mathematics. According to the membership theory of fuzzy mathematics, qualitative evaluation can be converted into quantitative evaluation. Since the performance intervals of different evaluation indicators are inconsistent, the characteristic values ​​of the evaluation indicators should be quantified to the same interval according to the membership function, which is more convenient for evaluating the adaptability of cryptographic technology and embedded systems. Similarly, this example uses the performance of AES-GCM as the benchmark, that is, AES-GCM is mapped to 60, and the remaining indicators have different membership functions.

[0070] (1) Randomness:

[0071]

[0072] (2) Anti-linear ability:

[0073] CM 12 =(log2S-AL-1)×20 2<S-AD≤64

[0074] (3) Anti-difference ability:

[0075]

[0076] (4) Time cost: C alg Indicates the time cost of the tested cryptographic algorithm.

[0077]

[0078] (5) Code size: CS alg Indicates the code size of the cryptographic algorithm being tested.

[0079]

[0080] (6) Flash: F alg Indicates the Flash memory usage of the tested cryptographic algorithm.

[0081]

[0082] (7) RAM: R alg Indicates the RAM usage of the tested cryptographic algorithm.

[0083]

[0084] (8)CPU usage: P alg Indicates the CPU usage of the tested cryptographic algorithm.

[0085]

[0086] (9) Throughput: T alg Indicates the throughput rate of the measured cryptographic algorithm.

[0087]

[0088] Step 5: The evaluation model is as follows. Assume that the set of cryptographic algorithms to be evaluated is E = {E1, E2, ..., E m}, evaluation criteria set 0 = {01, O2, ..., O i}, assuming that each evaluation criterion O i There arei evaluation index, for E in set E j For example, we can use vector Indicates n i The characteristic value of the evaluation index is shown in the following formula.

[0089]

[0090] The eigenvalues ​​of the M lightweight cryptographic algorithm evaluation indicators can be expressed by the following matrix:

[0091]

[0092] The eigenvalue matrix can then be transformed into the following membership level matrix using the membership function:

[0093]

[0094] in

[0095] Assume that n i The weight coefficient set of the evaluation indicators is expressed by the following formula:

[0096]

[0097] in Represents the weight coefficient of each evaluation indicator,

[0098] The above is a detailed description of the fuzzy multi-level adaptability evaluation model based on AHP.

[0099]

[0100] The above formula represents the result of each evaluation criterion, where Represents cryptographic algorithm E j In the evaluation criteria O i The fuzzy comprehensive evaluation results on the above can be used as the rows of higher-level evaluation results. By repeating the above steps, we can finally obtain the fuzzy comprehensive evaluation results of multiple cryptographic algorithms on multiple evaluation criteria.

[0101] Step 6: The evaluation results of the specific cryptographic algorithm and the specific embedded system (STM32F429) are shown below:

[0102]

[0103] ASCON has the highest adaptability. ASCON is fully compatible with GIFT-COFB. Elephant is compatible with PHOTON-Beetle in certain situations.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for evaluating the suitability of symmetric cryptographic technology for embedded systems, characterized in that: The method comprises the following steps: Step 1: Give a definition of adaptability; the adaptability of cryptographic technology and embedded systems refers to the applicability of cryptographic technology in embedded systems, which depends on the requirements of the target carrier system. Different carrier systems have different requirements and different adaptability performances. According to the different target carrier systems, give a definition of adaptability applicable to this target carrier system; Step 2: Construct an adaptability evaluation index system; construct a three-layer comprehensive adaptability evaluation index system. To evaluate the adaptability of cryptographic technology and embedded systems, it is necessary to comprehensively evaluate the security performance of cryptographic technology and the performance of cryptographic technology in the target system, so it includes two evaluation criteria: security and performance. Each evaluation criterion has multiple evaluation indicators, which together constitute the adaptability evaluation index system. Step 3: Determine the weight coefficient of the adaptability evaluation index; comprehensively evaluate the adaptability of cryptographic technology and embedded systems. Different evaluation indicators have different effects on embedded systems in practical applications. Determine the weight coefficient of the evaluation index to show the impact of each indicator in practical applications. Step 4: Quantify the characteristic values ​​of the adaptability evaluation indicators; use the fuzzy evaluation method to convert the qualitative evaluation into a quantitative evaluation based on the membership theory of fuzzy mathematics. Different evaluation indicators have different performance intervals. According to the membership function, the characteristic values ​​of the evaluation indicators are quantified to the same interval to evaluate the adaptability of the cryptographic technology and the embedded system. Step 5: Form a fuzzy multi-level adaptability evaluation model based on AHP and evaluate the adaptability performance of cryptographic technology and embedded systems; Steps 2, 3, and 4 constitute a fuzzy multi-level adaptability evaluation model based on AHP. The weight coefficient matrix and the eigenvalue matrix are multiplied to obtain a fuzzy comprehensive evaluation result. This result is used as a row of a higher-level evaluation result. Repeat step 5 to obtain fuzzy comprehensive evaluation results of multiple cryptographic algorithms on multiple evaluation criteria. Step 6: Give the corresponding relationship between the adaptability evaluation result and the adaptability definition; obtain the adaptability of the applied cryptographic technology and the target carrier system.

2. The method for evaluating the suitability of symmetric cryptographic technology for embedded systems according to claim 1, characterized in that: In the step 1, adaptability has two limitations: one is that the cryptographic algorithm being evaluated is limited to symmetric cryptographic technology; the other is the target carrier system, and the acceptable performance limits for different carrier systems are also different; a cryptographic algorithm with good adaptability needs to have sufficient security, fast execution speed and small resource occupation; different carrier systems have different requirements, and the definition of adaptability is given by setting an adaptability benchmark, including the cryptographic algorithms currently used in embedded systems as benchmarks; Among them, S A 、V A 、M A They represent the security level, execution efficiency and resource usage of cryptographic algorithm A in a specific embedded system, respectively. I For the required security level of this embedded system, V R 、M R They respectively represent the execution efficiency and resource usage of the benchmark cryptographic algorithm in this specific embedded system; 1 means that the cryptographic algorithm is fully compatible with the embedded system, α means that the cryptographic algorithm is not very compatible with the embedded system in some aspects, but can still be used in specific scenarios, and 0 means it is completely unsuitable.

3. The method for evaluating the suitability of symmetric cryptographic technology for embedded systems according to claim 2, characterized in that: In step 2, a three-layer comprehensive adaptability evaluation index system is constructed. The first layer is the comprehensive adaptability evaluation result A, the second layer is the safety standard B1 and the performance standard B2, and the third layer is the specific evaluation index, which are the randomness performance C under the safety standard. 11 , Linear attack resistance C 12 C 13 , the time cost under the performance standard C 21 , code size C 22 、Flash occupies C 23 、RAM occupancy C 24 、CPU usage C 25 With throughput C 26 ; Randomness is reflected by the results of fifteen typical randomness test methods for cryptographic algorithms, including frequency test, group frequency test, run test, maximum 1 run test, binary matrix rank test, discrete Fourier transform test, non-overlapping match test, overlapping match test, global universal test, linear complexity test, serial test, approximate entropy test, cumulative sum test, randomness offset test, and randomness offset test variant. The test results are all expressed in P-Value. Only P-Value ≥ 0.01 indicates that the algorithm has passed this test. It is proposed to use randomness RT to represent the randomness performance of the cryptographic algorithm: RT = (F*(FB+R+LRB+BMR+DFT+NoTM+OTM+MU+LC+S+AE+CS+RE+REV)) / 14 Among them, the right side shows the symbols of fifteen test methods. F represents the result of frequency test. Frequency test is the basis of all randomness tests and is represented by 0 or 1. F and other randomness tests are multiplicative, that is, only when the frequency test passes, other randomness tests are meaningful; the degree of randomness of an algorithm depends on the pass rate of the other test methods, and the other fourteen test methods are additive. The ability to resist linear attacks and differential attacks is determined by analyzing the S-box of the cryptographic algorithm. The maximum linear deviation of the S-box is used to represent the ability to resist linear attacks. The larger the deviation of the linear expression, the weaker the ability to resist linear attacks, which is represented by S-AL. The maximum differential probability of the S-box is used to represent the ability to resist differential attacks. The larger the differential probability, the weaker the ability to resist differential attacks, which is represented by S-AD. There are multiple evaluation indicators under the performance standard, and six indicators are used for evaluation, namely time overhead, code size, Flash occupancy, RAM occupancy, CPU occupancy and throughput; The indicator system meets the three aspects of adaptability mentioned in the adaptability definition, namely security, execution speed and resource usage.

4. The method for evaluating the suitability of symmetric cryptographic technology for embedded systems according to claim 3, characterized in that: In step 3, the analytic hierarchy process (AHP) is used to determine the weights of the evaluation indicators, which includes four steps: ① scale determination and construction of judgment matrix; ② eigenvector, eigenroot and weight calculation; ③ consistency test analysis; ④ analysis conclusion.

5. The method for evaluating the suitability of symmetric cryptographic technology for embedded systems according to claim 4, characterized in that: In step 4, different evaluation indicators have different characteristic values ​​and require different membership functions. The membership functions of different indicators are determined by combining the existing objective scale method and the assignment method according to the indicators of the existing cryptographic algorithm and the linear distribution method.

6. The method for evaluating the suitability of symmetric cryptographic technology for embedded systems according to claim 5, characterized in that: In step 5, it is assumed that the set of cryptographic algorithms to be evaluated is E={E1, E2, ..., E m }, evaluation criteria set O = {O1, O P , ..., O i }, assuming that each evaluation criterion O i There are i evaluation index, for E in set E j For example, using vector Indicates n i The characteristic value of the evaluation index is shown in the following formula: The eigenvalues ​​of the M lightweight cryptographic algorithm evaluation indicators are expressed in the following matrix: The eigenvalue matrix is ​​then transformed into the following membership level matrix using the membership function: in Assume that n i The weight coefficient set of the evaluation indicators is expressed by the following formula: in Represents the weight coefficient of each evaluation indicator, The above formula represents the result of each evaluation criterion, where Represents cryptographic algorithm E j In the evaluation criteria O i The fuzzy comprehensive evaluation results on the above are used as the rows of the higher-level evaluation results, and the above steps are repeated to finally obtain the fuzzy comprehensive evaluation results of multiple cryptographic algorithms on multiple evaluation criteria.

7. The method for evaluating the suitability of symmetric cryptographic technology for embedded systems according to claim 6, characterized in that: In step 6, the corresponding relationship between the adaptability evaluation result and the adaptability definition is as follows: Among them, EP A Represents the evaluation result of cryptographic algorithm A obtained using the adaptability evaluation model proposed in step 5.

Images