ATE test implementation method based on file encryption and decryption

Abstract

The application discloses a kind of encryption and decryption based on file ATE test implementation method, which is based on substitution encryption, increases a chain processing mechanism, different encryption and decryption functions are generated for each character position, and the encryption and decryption of the next character depends on the previous character. The characters replaced by the same character in different positions may be different and have a certain randomness. Therefore, the application uses the high efficiency of substitution encryption, hides the encryption key, increases the difficulty of cracking, forms an efficient and secure encryption algorithm, and does not require user input to decrypt the key. It solves the efficient and secure encryption and decryption of user engineering files in ATE devices.

Description

Technical Field

[0001] This invention relates to the field of semiconductor testing technology, and more specifically, to an ATE testing implementation method based on file encryption and decryption. Background Technology

[0002] Automatic Test Equipment (ATE) for Integrated Circuits (ICs) is widely used in the semiconductor industry. Currently, ATE testing verifies the functional integrity of integrated circuits, ensuring the quality of integrated circuit manufacturing.

[0003] ATE is divided into HOST and test machines. Please refer to [link / reference]. Figure 1 , Figure 1 The diagram shows a flowchart illustrating the user engineering encryption requirements of ATE devices in the prior art. For example... Figure 1 As shown, ATE equipment manufacturers will customize and develop user projects for different chips. During the testing process, the user project file is first encrypted using an external user project editing tool. Then, the host machine loads the encrypted user project and transfers the encrypted user project file to the test machine. The software development kit (SDK) loads the user project file and executes it.

[0004] Those skilled in the art will understand that user engineering includes data configuration files related to test data. Chip manufacturers require that these data configuration files be encrypted, and that reading and decrypting the files should not significantly affect the efficiency of the ATE test stream. The password input should not be interrupted during program execution. Therefore, ATE equipment manufacturers need to study the security and efficiency of reversible file encryption technology, and they also need to effectively hide the encryption and decryption keys.

[0005] Commonly used reversible file encryption techniques are as follows:

[0006] ① Substitution method

[0007] Substitution encryption is frequently used in processing temporary data in memory, such as bitwise inversion, incrementing or decrementing bits.

[0008] Analysis of the advantages and disadvantages of the above substitution method in ATE applications:

[0009] a. Encrypt by replacing characters at their positions;

[0010] b. High encryption efficiency;

[0011] c. Poor security, suitable for temporary data;

[0012] d. No password required.

[0013] ② DES encryption

[0014] DES (Data Encryption Standard) was developed in 1977 by the US NSA based on IBM's patented Lucifer technology. In DES, plaintext is divided into 64-bit blocks, and each block undergoes 19 transformations (substitutions and transpositions). Of these, 16 transformations are controlled by different permutations of a 56-bit key (IBM used a 128-bit key), ultimately producing a 64-bit ciphertext block.

[0015] The above analysis of the advantages and disadvantages of DES encryption in ATE applications:

[0016] a. Decrypt the private key's in-process constants;

[0017] b. Fixed-length encryption, which differs from file stream operation practices;

[0018] c. The technical methods are public, and security is only guaranteed when the user possesses the key;

[0019] d. With human intervention to obtain the private key, brute-force attacks are extremely difficult.

[0020] ③ AES encryption

[0021] Advanced Encryption Standard (AES), also known as Rijndael encryption in cryptography, is a block cipher standard adopted by the U.S. federal government. This standard has been extensively analyzed and is widely used worldwide. After a five-year selection process, AES was published by the National Institute of Standards and Technology (NIST) on November 26, 2001, in FIPS PUB 197, and became an effective standard on May 26, 2002. By 2006, AES had become one of the most popular algorithms in symmetric-key encryption.

[0022] The above analysis of the advantages and disadvantages of AES encryption in ATE applications:

[0023] a. Decrypt the private key and encrypt the public key in-process constants;

[0024] b. It is not efficient and is generally only suitable for processing small amounts of data;

[0025] c. Security is only achieved when the user possesses the key, making it unsuitable for encryption and decryption scenarios where no one is involved.

[0026] d. With human intervention to obtain the private key, brute-force attacks are extremely difficult.

[0027] However, the aforementioned encryption technologies share a common technical challenge: the data configuration files in the user's project are frequently used during testing. If decryption generates a cached file for later use, the protective effect is lost. Therefore, the encrypted file must be decrypted in memory as needed, without caching the disk file. This approach places very high demands on decryption efficiency. For example, for a 10MB file, the encryption and decryption processes must be controlled within milliseconds.

[0028] Table 1 compares the encryption and decryption efficiency of 10M data files.

[0029] Inverse substitution method 173.87 milliseconds 218.08 milliseconds Low DES 333.5 milliseconds 333.1 milliseconds high AES 250.4 milliseconds 274.2 milliseconds high

[0030] Based on the comparison of the above list of data, DES and AES encryption meet the security requirements and are not easy to crack, but they require the decryption key to be cached in memory, which does not meet the requirements. The substitution method does not meet the security requirements because it encrypts bit by bit. The same bit value will be the same after being encrypted according to the substitution algorithm. The injective and surjective methods of the same set of 256 values ​​can be easily cracked after certain data analysis and experiments.

[0031] In other words, although the replacement method is slightly more efficient for files smaller than 10MB, it is less secure. When using DES or AES encryption, it is also difficult to hide the decryption key, which must be stored somewhere in memory. Summary of the Invention

[0032] The purpose of this invention is to provide an ATE test implementation method based on file encryption and decryption, which can better hide the decryption key in the ATE device without human intervention while protecting the privacy of all parties.

[0033] To achieve the above objectives, the technical solution of the present invention is as follows:

[0034] An ATE testing method based on substitution-based file encryption and decryption is used to encrypt plaintext files of data configuration files in a user project. The plaintext file consists of bits, each bit is composed of characters, and all characters are unsigned integers. The set of all character values ​​is A = {0, 1, 2...255}. The method is characterized by including an encryption transmission step S1 and a decryption output step S2.

[0035] Step S1 includes:

[0036] Step S11: Before encrypting the plaintext file, select an encryption function generation formula; wherein the plaintext file contains n characters, and a different encryption function is used for each character position, and the encryption function generation formula is f. k (k takes values ​​from 1 to n):

[0037] {f1,f2,......f n-1 ,f n}

[0038] A dynamic encryption function set is formed; wherein the encryption function formula is an s-order chain encryption formula, where s is a positive integer, and the dynamic encryption function of each position character is initialized with the encryption seed by the position of the previous position character and the character of the current position character, where s is a positive integer;

[0039] Step S12: Based on the initial encryption seed, determine the encryption seed for each character to be encrypted in the plaintext file, generate a new dynamic encryption function, form the ciphertext file of the plaintext file, and send the ciphertext file to the HOST machine;

[0040] Step S13: The HOST machine sends the encrypted file to the Software Development Kit (SDK) according to the request;

[0041] Step S2 includes:

[0042] Step S21: Before encrypting the ciphertext file, select an encryption function generation formula; wherein the ciphertext file contains n characters, and a different decryption function is used for each character position, and the decryption function generation formula is f′. k (k takes values ​​from 1 to n):

[0043] {f′1,f′2,......f′ n-1 ,f′ n}

[0044] A set of dynamic decryption functions is formed; wherein, the dynamic decryption function formula is an s-order chain decryption formula, where s is a positive integer, and the dynamic decryption function of each position character is initialized with the decryption seed by the position of the next position character and the character value of the current position character;

[0045] Step S22: Based on the initial decryption seed, determine the decryption seed for each character to be decrypted in the ciphertext file, generate a new dynamic decryption function, restore the ciphertext file to the original plaintext file, load the user project file, and execute.

[0046] Furthermore, the dynamic encryption / decryption function formula is a univariate formula: y = (x + b) % 256, where x is the plaintext character, y is the ciphertext character to be output, and b is a constant. For each character to be encrypted, a new encryption function is generated as long as different encryption seed values ​​b are generated; where B is defined as the function from the encryption seed to b, the plaintext file has n characters, and the range of values ​​of b forms the set {b1, b2, ... b}. n-1,b n}

[0047] Furthermore, the b k Value generation involves selecting a set of encryption seeds for each character position and character value. Where k is the character position, ranging from 1 to n, l is the encryption seed number, ranging from 1 to s, and s is the number of encryption seeds.

[0048] Furthermore, the b k The value is generated by a dynamic decryption function formula that is at least a first-order chained encryption formula. The encryption algorithm is named according to the number 's' of encryption seeds generated; 's' encryption seeds constitute an 's'-order' encryption algorithm.

[0049] Select an encryption seed, This forms the first-order encryption function generation formula f. k :

[0050] Select two encrypted seeds, This forms the formula for generating the second-order encryption function f. k :

[0051] …

[0052] Select s encryption seeds, This forms the formula for generating the s-order encryption function f. k :

[0053] As can be seen from the above technical solution, the ATE testing implementation method based on file encryption and decryption proposed in this invention adds a chain processing mechanism to the substitution encryption method. Different encryption and decryption functions are generated for each character position, and the encryption and decryption of the subsequent character depends on the previous character. The same character may replace different characters in different positions, exhibiting a certain degree of randomness. This method utilizes the high efficiency of substitution encryption while hiding the encryption key, increasing the difficulty of cracking, thus forming a highly efficient and secure encryption algorithm. Furthermore, it does not require user input of the decryption key, addressing the high efficiency and high security requirements for encryption and decryption of user project files in ATE equipment. Attached Figure Description

[0054] Figure 1 The diagram shown is a flowchart of the user engineering encryption requirements for ATE devices in the prior art.

[0055] Figure 2 The diagram shown is a flowchart illustrating the ATE test implementation method based on file encryption and decryption in an embodiment of the present invention.

[0056] Figure 3 The diagram shown is a schematic representation of the encryption process in an embodiment of the present invention.

[0057] Figure 4 The diagram shown is a schematic representation of the decryption process in an embodiment of the present invention. Detailed Implementation

[0058] The following is in conjunction with the appendix Figure 1-4 The specific embodiments of the present invention will be further described in detail below.

[0059] It should be noted that this invention is based on the idea of ​​substitution encryption and decryption, and treats all characters as unsigned integers. Therefore, the set of all character values ​​A = {0, 1, 2...255} is a set of 256 values. The unary function y = f(x) is a one-to-one mapping from A to A, and its inverse function y = f'(x) is also a one-to-one mapping from A to A. Characters can be encrypted and decrypted using the function y = f(x) and its inverse function y = f'(x), with all characters using the same formula. Following the extended approach of existing substitution techniques, this invention adds a chain-like processing mechanism to the substitution encryption method.

[0060] Please combine Figure 1 See Figure 2 , Figure 2 The diagram shown is a schematic flowchart of an ATE test implementation method based on file encryption and decryption in an embodiment of the present invention. Figure 2 As shown, the ATE test method based on substitution-based file encryption and decryption is used to encrypt plaintext files of data configuration files in user projects. The plaintext file consists of bits, each bit is composed of characters, and all characters are unsigned integers. The set of all character values ​​is A = {0, 1, 2... 255}.

[0061] In an embodiment of the present invention, step S1 includes:

[0062] Step S11: Before encrypting the plaintext file, select an encryption function generation formula; wherein the plaintext file contains n characters, and a different encryption function is used for each character position, and the encryption function generation formula is f. k (k takes values ​​from 1 to n):

[0063] {f1,f2,......f n-1 ,f n}

[0064] A dynamic encryption function set is formed; wherein the encryption function formula is an s-order chain encryption formula, where s is a positive integer, and the dynamic encryption function of each position character is initialized with the encryption seed by the position of the previous position character and the character value of the current position character; where s is a positive integer.

[0065] In the embodiments of the present invention, each position corresponds to a different encryption and decryption function, and the encrypted ciphertext content is random. The same character value may have different replacement values ​​in different positions in the file.

[0066] Specifically, each character requires an encryption function, which needs to be dynamically generated. For example, a unary formula y = (x + b) % 256 can be used to generate it (x is the plaintext character, y is the ciphertext character to be output, and b is a constant). This formula is a one-to-one mapping from A to A.

[0067] For each character to be encrypted, a new encryption function is generated by producing different values ​​for b. The file has n characters, and the possible values ​​of b form a set {b1, b2, ..., bn}. n-1 ,b n}

[0068] In an embodiment of the present invention, the b k The generation of values ​​involves selecting a set of encryption seeds based on the specific position and value of each character. Where k is the character position, ranging from 1 to n, l is the encryption seed number, ranging from 1 to s, and s is the number of encryption seeds.

[0069] In other words, b k Value generation can be performed by initializing the selection of a cryptographic seed set for each position and character value. See the table below for encrypted seed generation:

[0070]

[0071] Step S12: Based on the determined initial encryption seed, determine the encryption seed for each character to be encrypted in the plaintext file, generate a new dynamic encryption function, form the ciphertext file of the plaintext file, and send the ciphertext file to the HOST machine.

[0072] Suppose we define B as a function of the encryption seed to b, and name the encryption algorithm according to the number of encryption seeds generated; the number of encryption seeds determines the order of the encryption algorithm.

[0073] The b kThe value is generated by a dynamic decryption function formula that is at least a first-order chained encryption formula. B is defined as a function from the encryption seed to b. The encryption algorithm is named according to the number s of encryption seeds generated; s encryption seeds constitute an s-order encryption algorithm.

[0074] Select an encryption seed, This forms the first-order encryption function generation formula f. k :

[0075] Select two encrypted seeds, This forms the formula for generating the second-order encryption function f. k :

[0076] …

[0077] Select s encryption seeds, This forms the formula for generating the s-order encryption function f. k :

[0078] Similarly, selecting multiple encryption seeds generates multi-order encryption functions. The higher the order of function B, the more complex the mapping relationship, and the more difficult it is to crack. This is because the cracker not only needs to know the function generation formula but also the method for selecting encryption seeds.

[0079] For each position of the string, by dynamically selecting the value of b, we generate a series of encryption functions f in a chain. k The corresponding inverse function f′ k This is the decryption function, which is the core idea behind the chain-substitution encryption / decryption algorithm of this invention. This method distributes the conventional encryption key into two parts: an encryption seed and an encryption formula. Knowing only a portion of the encryption seed is insufficient; all encryption seeds and formulas must be known. This requires the cracker to have complete mastery of the disassembled program logic, which is virtually impossible, thus ensuring security.

[0080] Step S13: The HOST machine sends the encrypted file to the Software Development Kit (SDK) according to the request.

[0081] Step S2 includes:

[0082] Step S21: Before encrypting the ciphertext file, select an encryption function generation formula; wherein the ciphertext file contains n characters, and a different decryption function is used for each character position, and the decryption function generation formula is f′. k (k takes values ​​from 1 to n):

[0083] {f′1,f′2,......f′ n-1,f′ n}

[0084] A set of dynamic decryption functions is formed; wherein, the dynamic decryption function formula is an s-order chain decryption formula, where s is a positive integer, and the dynamic decryption function of each position character is initialized with the decryption seed by the position of the next position character and the character value of the current position character;

[0085] Step S22: Based on the initial decryption seed, determine the decryption seed for each character to be decrypted in the ciphertext file, generate a new dynamic decryption function, restore the ciphertext file to the original plaintext file, load the user project file, and execute.

[0086] Example 1

[0087] To facilitate understanding, the following section will provide a detailed explanation of the ATE test method for file encryption and decryption based on the substitution method, using a second-order chain encryption formula as an example.

[0088] In a specific implementation of this invention, a second-order chained encryption formula B is used: b = 3 * index * iSeed

[0089] The encryption function generation formula f: y = (x + 3 * index * iSeed) % 256

[0090] The decryption function generates the formula f': y = (255 - x - (3 * iIndex * chSeed) % 256) < 0? (255 - x - (3 * iIndex * chSeed) % 256) + 256 : (255 - x - (3 * iIndex * chSeed) % 256)

[0091] Where index is the position of the character, and the set {1,2,...n} is selected sequentially;

[0092] iSeed is the encryption seed, which is selected sequentially from the set {file size n, first character value, second character value, ..., n-1th character value}.

[0093] 1) Encryption process

[0094] Please see Figure 3 , Figure 3 The diagram shown is a schematic representation of the encryption process in an embodiment of the present invention. Figure 3 As shown, the encryption process is as follows:

[0095] f1: Substituting formula f into (1, n) generates the encryption function.

[0096] f2: Substitute formula f into (2, a1) to generate the encryption function. ...

[0098] Following the diagram, substitute the characters one by one. Each encryption formula encrypts only the character at the current position.

[0099] Please refer to Figure 3

[0100] 2) Decryption process

[0101] See Figure 4 , Figure 4 The diagram shown illustrates the decryption process in an embodiment of the present invention. It follows the same principle as the encryption process, using the same key seed sequence:

[0102] f′1: Substituting the formula f′ into (1, n) generates the decryption function.

[0103] f′2: Substituting the formula f′ into (2, a1) generates the decryption function. ...

[0105] Substitute the values ​​one by one according to the diagram.

[0106] The difference between the decryption algorithms is that, in the decryption process, the preceding characters need to be decrypted first in order to obtain the decryption seed for the next character. This chain reaction mode can effectively protect the file, and it is ineffective for crackers to analyze the characteristics of only one segment.

[0107] Using this chain-based decryption approach, multi-level dependency encryption can be employed, such as one character depending on the values ​​of the preceding two characters. Furthermore, certain strategies can be used to increase complexity and confuse attackers by shuffling the input order of the key seed's arguments in encryption formula B based on the parity of its positions.

[0108] Additionally, it should be noted that the embodiments of this invention employ a cache-free decryption file design. Normally, reading an encrypted file requires first decrypting it into a plaintext file, and then using relevant text parsing tools.

[0109] For security reasons, this invention does not use file caching, but instead employs the following two measures to directly decrypt and convert in memory:

[0110] (1) Design encryption tokens

[0111] An encryption marker is appended to the end of the encrypted file. This distinguishes plaintext and ciphertext files and effectively prevents brute-force attacks when the file content is short. The encryption marker is also encrypted using the algorithm of this invention, further enhancing security.

[0112] (2) Overload the file operation classes of the language

[0113] For example, C++ uses overloaded file operation classes such as FileStream and File to distinguish between encrypted and plaintext files. These overloaded file operation classes are used to decrypt files in memory, achieving the same reading effect as plaintext files.

[0114] In summary, comparing the computational scheme of this invention with the classical scheme, the main advantage of the above scheme is that it solves the high efficiency and high security requirements for encryption and decryption of user project files in ATE equipment. Experimental results show:

[0115] 1) The ATE test implementation method (chain substitution method) for file encryption and decryption based on this invention, and the encryption and decryption efficiency of DES and AES encryption algorithms:

[0116] For example, a test file of 10MB, calculate the average of 10 tests.

[0117] Chain substitution method 193.43 milliseconds 226.153 milliseconds AES 250.4 milliseconds 274.2 milliseconds DES 333.5 milliseconds 333.1 milliseconds

[0118] Data comparison shows that the chain substitution method is slightly more efficient than the classic AES and DES algorithms in both encryption and decryption.

[0119] 2) Efficiency analysis of the application of the chain replacement method in ATE equipment

[0120] ① Test conditions

[0121] P350+8000L Dual-Frame Test Chamber

[0122] Host Configuration

[0123] Windows Server 2019

[0124] CPU Intel Xeon 3.3

[0125] 16GB RAM

[0126] C drive: 250GB SSD, sequential write speed 2000MB / s

[0127] ONES installation on C drive

[0128] Test machine

[0129] 38 D800NP digital boards

[0130] 2 main control boards

[0131] 1 monitoring board

[0132] Test configuration

[0133] Full frame, 4Site mode, 1216 DUTs, 200 test items

[0134] ② Test case decryption time on the test machine

[0135]

[0136] ③ SDK initialization consumes one decryption time.

[0137] Comparison of full-frame loading efficiency parameters for dual-frame layouts

[0138] Print time format: minutes.seconds.milliseconds

[0139]

[0140] The loading process includes three steps: unloading, loading, and initialization. Finally, other external processes need to be opened, which can lead to a relatively large error. The test data is the average of three repeated trials.

[0141] in conclusion:

[0142] The loading time during the loading process is related to the overall size of the user project; the time consumed by encryption and decryption is negligible. The time consumed by encryption and decryption is not even as large as the time error of the entire call waiting process.

[0143] ④ Double-frame full-frame single TOUCH test time

[0144] Print time format: minutes.seconds.milliseconds

[0145]

[0146] in conclusion:

[0147] Project size has no impact on Touch execution time.

[0148] As the number of user logs increased, the testing time became longer.

[0149] As can be seen from the data above, the decryption time of the chain substitution method is measured in milliseconds, which is negligible compared to the test time error.

[0150] The above description is merely a preferred embodiment of the present invention. The embodiments are not intended to limit the scope of patent protection of the present invention. Therefore, any equivalent structural changes made based on the description and drawings of the present invention should also be included within the scope of protection of the present invention.

Claims

1. An ATE test method based on file encryption and decryption by replacement, for encrypting a plaintext file of a data configuration file in a user engineering, wherein, The plaintext file consists of bits, each bit is composed of characters, and all characters are unsigned integers. The set of all character values ​​is A = {0, 1, 2...255}. The method is characterized by including an encryption transmission step S1 and a decryption output step S2. Step S1 includes: Step S11: Before the encryption of the plaintext file, select an encryption function generating formula; wherein the plaintext file has n characters, and a different encryption function is used for each position character, and the encryption function generating formula is f k : {f1,f2,......f n-1 ,f n } A dynamic encryption function set is formed; where k is the character position index, and the value range is from 1 to n; the encryption function formula is an s-order chain encryption formula, where s is a positive integer, and the dynamic encryption function of each position character is initialized with the character value of the previous position character and the character position of the current position character. Step S12: Encrypt each character to be encrypted sequentially from the first character to the last character; wherein, for the first character, its encryption seed is determined based on a first initial value; for the k-th character (k≥2), its encryption seed is determined based on the position of the current character and the plaintext value of the (k-1)-th character; according to the determined encryption seed, a dynamic encryption function for that character is generated and encrypted, thereby forming the ciphertext file of the plaintext file, and the ciphertext file is sent to the HOST machine; Step S13: The HOST machine sends the encrypted file to the Software Development Kit (SDK) according to the request; Step S2 includes: Step S21: before performing the ciphertext file decryption, select a decryption function generation formula; wherein the ciphertext file has n characters, and a different decryption function is used for each position character, and the decryption function generation formula is f′ k : {f′1,f′2,......f′ n-1 ,f′ n } A set of dynamic decryption functions is formed; where k is the character position index, and the value range is from 1 to n; the dynamic decryption function formula is an s-order chain decryption formula, where s is a positive integer, and the dynamic decryption function of each position character is initialized with the character value of the previous position character and the character position of the current position character. Step S22: Decrypt each character to be decrypted sequentially from the first character to the last character; wherein, for the first character, its decryption seed is determined based on the first initial value; for the k-th character k≥2, its decryption seed is determined based on the position of the current character and the plaintext value of the (k-1)-th character that has been decrypted; according to the determined decryption seed, a dynamic decryption function for the character is generated and decrypted, thereby restoring the ciphertext file to the original plaintext file, loading the user project file, and executing it.

2. The ATE testing method based on substitution-based file encryption / decryption according to claim 1, characterized in that, The dynamic encryption function and the dynamic decryption function are a unary formula: y=(x+b) % 256; wherein x is a plaintext character, y is a ciphertext character to be output; b is a constant dynamically generated for each character according to the encryption seed, for each character to be encrypted, as long as a different encryption seed b value is generated, a new encryption function is generated; wherein B is defined as a function of the encryption seed to b, the plaintext file has n characters, and the value domain of b forms a set , ... , }.

3. The ATE testing method based on substitution-based file encryption / decryption according to claim 2, characterized in that, The value generation comprises: determining, for a character position of the kth character, an s-order encryption seed set corresponding to the character position ; wherein k is the character position, the value range is 1~n, l is the serial number of the encryption seed, the value range is 1~s, and s is the number of the encryption seed, i.e. the order of the encryption algorithm.

4. The ATE testing method based on substitution-based file encryption / decryption according to claim 3, characterized in that, The values are generated by a function B based on the s-order set of encryption seeds, and the dynamic encryption function is at least one order of chain encryption formula. According to the number s of generated encryption seeds, the encryption algorithm is named, and s encryption seeds are s-order encryption algorithm: Select an encryption seed, This forms the first-order encryption function generation formula f. k : ; Select two encrypted seeds, This forms the second-order encryption function generation formula f. k : ; Select s encryption seeds, This forms the formula for generating the s-order encryption function f. k : .

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