kgg-dec/src/main.cpp

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// clang-format off
#include <windows.h>
#include <shlobj.h>
#include <initguid.h>
#include <knownfolders.h>
// clang-format on
#include <cstdint>
#include <cstdio>
#include <cstring>
#include <filesystem>
#include <fstream>
#include <span>
#include "infra/infra.h"
#include "infra/sqlite_error.h"
#include "qmc2/qmc2.h"
using Infra::kgm_ekey_db_t;
constexpr std::array<uint8_t, 16> kMagicHeader{0x7C, 0xD5, 0x32, 0xEB, 0x86, 0x02, 0x7F, 0x4B,
0xA8, 0xAF, 0xA6, 0x8E, 0x0F, 0xFF, 0x99, 0x14};
void DecryptKGG(const kgm_ekey_db_t& ekey_db, const std::filesystem::path& kgg_file) {
auto kgg_fname = kgg_file.filename().wstring();
fwprintf(stderr, L"[INFO] reading %s...\n", kgg_fname.c_str());
std::ifstream ifs_kgg(kgg_file, std::ios::binary);
char header[0x100]{};
ifs_kgg.read(header, sizeof(ifs_kgg));
if (std::equal(kMagicHeader.cbegin(), kMagicHeader.cend(), header)) {
fprintf(stderr, "[WARN] invalid kgg header, skip.\n");
return;
}
uint32_t offset_to_audio = *reinterpret_cast<uint32_t*>(&header[0x10]);
uint32_t encrypt_mode = *reinterpret_cast<uint32_t*>(&header[0x14]);
if (encrypt_mode != 5) {
fprintf(stderr, "[WARN] invalid enc_version (expect=0x05, got 0x%02x), skip.\n", encrypt_mode);
return;
}
uint32_t audio_hash_len = *reinterpret_cast<uint32_t*>(&header[0x44]);
if (audio_hash_len != 0x20) {
fprintf(stderr, "[WARN] audio hash length invalid (expect=0x20, got 0x%02x), skip.\n", audio_hash_len);
return;
}
std::string audio_hash(&header[0x48], &header[0x48 + audio_hash_len]);
std::string ekey{};
if (auto it = ekey_db.find(audio_hash); it != ekey_db.end()) {
ekey = it->second;
} else {
fprintf(stderr, "[WARN] ekey not found, skip.\n");
return;
}
auto qmc2 = QMC2::Create(ekey);
if (!qmc2) {
fprintf(stderr, "[WARN] create qmc2 failed, skip.\n");
return;
}
ifs_kgg.seekg(offset_to_audio, std::ios::beg);
std::vector<uint8_t> buffer(1024 * 1024);
ifs_kgg.read(reinterpret_cast<char*>(buffer.data()), buffer.size());
auto n = static_cast<size_t>(ifs_kgg.gcount());
qmc2->Decrypt(std::span(buffer.begin(), n), 0);
auto decrypted_path = kgg_file;
auto magic = std::span(buffer.cbegin(), 4);
if (std::equal(magic.begin(), magic.end(), "fLaC")) {
decrypted_path.replace_filename(decrypted_path.stem().wstring() + L"_kgg-dec.flac");
} else if (std::equal(magic.begin(), magic.end(), "OggS")) {
decrypted_path.replace_filename(decrypted_path.stem().wstring() + L"_kgg-dec.ogg");
} else {
decrypted_path.replace_filename(decrypted_path.stem().wstring() + L"_kgg-dec.mp3");
}
if (exists(decrypted_path)) {
fprintf(stderr, "[WARN] output file '%s' exists, skip.\n", decrypted_path.filename().string().c_str());
return;
}
std::ofstream ofs_decrypted(decrypted_path, std::ios::binary);
ofs_decrypted.write(reinterpret_cast<char*>(buffer.data()), n);
size_t offset{n};
while (!ifs_kgg.eof()) {
ifs_kgg.read(reinterpret_cast<char*>(buffer.data()), buffer.size());
n = static_cast<size_t>(ifs_kgg.gcount());
qmc2->Decrypt(std::span(buffer.begin(), n), offset);
ofs_decrypted.write(reinterpret_cast<char*>(buffer.data()), n);
offset += n;
}
auto decrypted_fname = decrypted_path.filename().wstring();
fwprintf(stderr, L"[INFO] OK! kgg --> %s\n", decrypted_fname.c_str());
}
void WalkFileOrDir(const kgm_ekey_db_t& ekey_db, const std::filesystem::path& input_path) {
if (is_directory(input_path)) {
for (auto const& dir_entry : std::filesystem::directory_iterator{input_path}) {
DecryptKGG(ekey_db, dir_entry.path());
}
} else if (is_regular_file(input_path)) {
DecryptKGG(ekey_db, input_path);
}
}
int main() {
SetConsoleOutputCP(CP_UTF8);
setlocale(LC_ALL, ".UTF8");
fputs("kgg-dec v0.1 by LSR\n", stderr);
fputs("Usage: kgg-dec [kgg-dir=.]\n\n", stderr);
PWSTR pAppDirPath{};
SHGetKnownFolderPath(FOLDERID_RoamingAppData, 0, nullptr, &pAppDirPath);
std::filesystem::path kgmPath{pAppDirPath};
CoTaskMemFree(pAppDirPath);
kgmPath = kgmPath / L"Kugou8" / L"KGMusicV3.db";
int error{-1};
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Infra::KugouDb db{L"infra.dll", kgmPath};
if (!db.IsOpen()) {
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fprintf(stderr, "[ERR ] db init error: is infra.dll ok?\n");
return 1;
}
auto ekey_db = db.dump_ekey(error);
if (error != 0) {
fprintf(stderr, "[ERR ] dump ekey failed %d (%s)", error, sqlite_get_error(error));
return 1;
}
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db.Close();
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#ifdef _DEBUG
printf("ekey_db:\n");
for (auto& [a, b] : ekey_db) {
printf("%s --> %s\n", a.c_str(), b.c_str());
}
#endif
int argc;
wchar_t** argv = CommandLineToArgvW(GetCommandLineW(), &argc);
std::filesystem::path input_dir{(argc < 2) ? L"." : argv[1]};
input_dir = absolute(input_dir);
WalkFileOrDir(ekey_db, input_dir);
return 0;
}