airborne/shared/crypto.cpp

#include "crypto.hpp"

std::vector<BYTE> GenerateKey(size_t keysize) {
  std::vector<BYTE> key(keysize, 0);
  std::random_device rd;
  std::mt19937 gen(rd());
  std::uniform_int_distribution<> dis(0, 255);

  for (size_t i = 0; i < key.size(); ++i) {
    key[i] = static_cast<BYTE>(dis(gen));
  }

  return key;
}

void XorCipher(std::vector<BYTE> *data, const std::vector<BYTE> &key) {
  for (size_t i = 0; i < data->size(); i++) {
    (*data)[i] = (*data)[i] ^ key[i % key.size()];
  }
}

DWORD CalculateHash(const std::string &source) {
  auto dwHash = HASH_KEY;

  for (char ch : source) {
    if (ch == '\0') {
      continue;
    }

    if (ch >= 'a' && ch <= 'z') {
      ch -= 0x20;
    }

    // Casting might be unnecessary
    dwHash = ((dwHash << 5) + dwHash) + static_cast<DWORD>(ch);
  }

  return dwHash;
}

DWORD CalculateHash(const UNICODE_STRING &baseDllName) {
  auto pwszBaseDllName = baseDllName.Buffer;
  auto dwHash = HASH_KEY;

  char ch;

  for (auto i = 0; i < baseDllName.MaximumLength; i++) {
    ch = pwszBaseDllName[i];

    if (ch == '\0') {
      continue;
    }

    if (ch >= 'a' && ch <= 'z') {
      ch -= 0x20;
    }

    // Casting might be unnecessary
    dwHash = ((dwHash << 5) + dwHash) + static_cast<DWORD>(ch);
  }

  return dwHash;
}