Code protection technology in C++

With the popularization of computer technology, computer software has become more and more important. In computer software development, C language is widely used. However, developers will find that their C code may be stolen, copied, and tampered with by criminals, leading to privacy leaks and theft of trade secrets. Therefore, protecting the security of C code is very important for software developers. This article will introduce several code protection techniques in C.

1. Symbol obfuscation technology

Symbol obfuscation technology is a technology that confuses the names and types of functions and global variables to ensure function interfaces. By modifying the function names and variable names in the code, the code is difficult to read and understand. In this way, it is difficult for an attacker to know the role of functions and variables and obtain useful information from them. Therefore, symbol obfuscation technology is often used to protect software trade secrets and important codes.

The implementation principle of symbol obfuscation technology is to change the function name and global variable name to some irregular characters or numbers, and then save the original function name and variable name in a table. When a program calls a function or variable, the called name is mapped back to the original name. This technique improves the security of the code by changing the string representation of the function name so that an attacker cannot guess the function name.

2. String encryption technology

In C code, strings are inevitable because strings are a basic type for storing and processing text and character data. The strings are contained in clear text within the executable file, meaning an attacker can easily extract and analyze the strings. Therefore, in order to ensure code security, string encryption technology is widely used.

String encryption technology can convert strings into encrypted text at compile time by using encryption algorithms. In this way, the original string is hidden in the executable file, and attackers cannot easily obtain the string content. .

For example, the plaintext string "Hello, World!" can be converted into a ciphertext string, as shown below:

char str[14] = {0x36, 0x3d, 0x3a, 0x3a, 0x21, 0x39, 0x2c, 0x3e, 0x38, 0x22, 0x00};

When accessing the ciphertext string in the program, you can pass The decryption algorithm reduces it to a plaintext string. This technique effectively protects the strings in the program from being easily seen by attackers.

3. Code obfuscation technology

Code obfuscation technology makes the code difficult to understand by changing the structure and flow of the code, making it difficult for attackers to crack the code. Code obfuscation technology is usually implemented in the following ways:

1. Control flow flattening: converting complex conditional statements and loop statements in the source code into linear code, making it impossible for attackers to judge based on the control flow of the code The internal logic of the software.
2. Instruction mutation: Replace assembly language instructions in the code with equivalent instructions so that attackers cannot parse the code through disassembly software.
3. Embedding useless code: Embedding useless code or dead code into the program makes it difficult for attackers to find the correct code path from the embedded code.

Code obfuscation technology can be performed at compile time or run time, and can effectively protect code security by reducing the readability and understandability of the code.

Summary

C is an excellent programming language that is widely used in software development. However, with the development of computer technology, C code protection has become more and more important. In this article, we introduce several techniques to protect C code security, such as symbol obfuscation technology, string encryption technology and code obfuscation technology. These technologies can effectively protect the security of program code and prevent the code from being stolen, tampered with or copied by attackers.

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