How do C++ functions implement network security in network programming?

C function can achieve network security in network programming. Methods include: 1. Using encryption algorithm (openssl) to encrypt communication; 2. Using digital signature (cryptopp) to verify data integrity and sender identity; 3. Defense against cross-site Script attacks (htmlcxx) filter and sanitize user input.

Safe implementation of C functions in network programming

In modern network programming, ensuring the security of communication is crucial . C provides a rich set of data types and functions that enable programmers to easily implement network security measures.

1. Use encryption algorithm

Encryption is one of the most commonly used security technologies to protect network communications. The C standard library provides several encryption algorithms out of the box, such as openssl.

#include <openssl/sha.h>

int main() {
  char message[] = "This is a secret message";
  SHA256_CTX ctx;
  unsigned char digest[SHA256_DIGEST_LENGTH];

  SHA256_Init(&ctx);
  SHA256_Update(&ctx, message, strlen(message));
  SHA256_Final(digest, &ctx);

  // 打印哈希值
  for (int i = 0; i < SHA256_DIGEST_LENGTH; i++) {
    printf("%02x", digest[i]);
  }

  return 0;
}

2. Verify digital signature

Digital signature is used to verify the integrity of the data and the identity of the sender. The cryptopp library in C provides rich digital signature functions.

#include <cryptopp/rsa.h>
#include <cryptopp/base64.h>
#include <cryptopp/osrng.h>

int main() {
  AutoSeededRandomPool rng;
  RSA::PrivateKey privateKey;
  RSA::PublicKey publicKey;
  privateKey.GenerateRandomWithKeySize(rng, 2048);
  publicKey.AssignFrom(privateKey);

  // 创建消息和签名
  byte message[] = "This is a signed message";
  byte signature[RSA::signature_length];
  privateKey.SignMessage(rng, message, sizeof(message), signature);

  // 验证签名
  bool verified = publicKey.Validate(message, sizeof(message), signature);

  if (verified) {
    cout << "签名已验证！" << endl;
  } else {
    cout << "签名无效！" << endl;
  }

  return 0;
}

3. Defense against cross-site scripting attacks

Cross-site scripting attack (XSS) is a common network attack that injects malicious scripts into user browsers to steal sensitive information. The htmlcxx library in C can help filter and sanitize user input.

#include <htmlcxx/htmlcxx.h>
#include <iostream>

int main() {
  string input = "<script>alert('XSS攻击！')</script>";

  htmlcxx::HTML::ParserDom parser;

  // 过滤和消毒输入
  tree<htmlcxx::HTML::Node> dom = parser.parse(input);
  htmlcxx::HTML::Node::iterator it = dom.begin();
  while (it != dom.end()) {
    if (it->isComment() || it->isText()) {
      it->swap(it->next());
      it = it->next();
    } else {
      ++it;
    }
  }

  // 输出已过滤的输入
  cout << dom.generate() << endl;

  return 0;
}

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