Telegram/SourceFiles/storage/details/storage_file_utilities.cpp:ReadFile() {   // ...  // check signature  HashMd5 md5;  md5.feed(bytes.constData(), dataSize);  md5.feed(&dataSize, sizeof(dataSize));  md5.feed(&version, sizeof(version));  md5.feed(magic, TdfMagicLen);  if (memcmp(md5.result(), bytes.constData() + dataSize, 16)) {    DEBUG_LOG(("App Info: bad file '%1', signature did not match"              ).arg(name));    continue;  }  // ...}

FileKey GenerateKey(const QString &basePath) {  FileKey result;  QString path;  path.reserve(basePath.size() + 0x11);  path += basePath;  do {    result = base::RandomValue<FileKey>(); // using FileKey = quint64;    path.resize(basePath.size());    path += ToFilePart(result);  } while (!result || KeyAlreadyUsed(path));  return result;}

QString ToFilePart(FileKey val) {  QString result;  result.reserve(0x10);  for (int32 i = 0; i < 0x10; ++i) {    uchar v = (val & 0x0F);    result.push_back((v < 0x0A) ? ('0' + v) : ('A' + (v - 0x0A)));    val >>= 4;  }  return result;}

调用prepareAES_oldmtp()函数，使用localKey和messageKey生成aesKey ->  调用aesIgeDecryptRaw()函数，使用aesKey来解密数据 ->    使用SHA1算法校验数据的完整性

decrypted = decryptLocal(mapEncrypted, localKey)
def decryptLocal(encrypted, key):    encryptedKey = encrypted[:16]    decrypted = aesDecryptLocal(encrypted[16:], key, encryptedKey)
    digest = sha1(decrypted)[:16]    if digest != encryptedKey:        raise ValueError('App Info: bad decrypt key, data not decrypted')  def aesDecryptLocal(src, authkey, key128):    aesKey, aesIV = prepareAES_oldmtp(authkey, key128)
    dst = bytearray(len(src))    buffer = ffi.from_buffer(dst)    ffi_openssl.aesIgeDecryptRaw(src, buffer, len(src), aesKey, aesIV)

调用ReadFile()函数获取加密数据 ->   调用DecryptLocal()函数，使用localkey解密加密的数据 ->    解析明文数据，进行序列化等操作

// https://github.com/desktop-app/lib_storage/blob/master/storage/cache/storage_cache_database_object.cppQString PlaceFromId(PlaceId place) {  auto result = QString();  result.reserve(15);  const auto pushDigit = [&](uint8 digit) {    const auto hex = (digit < 0x0A)      ? char('0' + digit)      : char('A' + (digit - 0x0A));    result.push_back(hex);  };  const auto push = [&](uint8 value) {    pushDigit(value & 0x0F);    pushDigit(value >> 4);  };  for (auto i = 0; i != place.size(); ++i) {    push(place[i]);    if (!i) {      result.push_back('/');    }  }  return result;}
// 示例：// std::array<uint8_t, 7> place = {1, 2, 3, 4, 5, 6, 7};// PlaceFromId(place) = "11/223344556677"

constexpr auto kSaltSize = size_type(64);constexpr auto kSha256Size = size_type(32);
struct BasicHeader {  bytes::array<kSaltSize> salt = { { bytes::type() } };  uint32 format : 8; // 位域  uint32 reserved1 : 24;  uint32 reserved2 = 0;  uint64 applicationVersion = 0;  bytes::array<openssl::kSha256Size> checksum = { { bytes::type() } };};

with open(path, 'rb') as f:  if f.read(4) != b'TDEF':    raise ValueError('wrong file type')
    salt = f.read(64)    encrypted = f.read(16 + 32)
    real_key = sha256(key[:len(key) // 2] + salt[:32])    iv = sha256(key[len(key) // 2:] + salt[32:])[:16]    d = CtrState(real_key, iv)
    data = d.encrypt(encrypted)    checksum = data[16:]
    if sha256(key + salt + data[:16]) != checksum:      raise ValueError('wrong key')
    return d.encrypt(f.read())

def decryptLocal(encrypted, key) -> bytes:    encryptedKey = encrypted[:16]    decrypted = aesDecryptLocal(encrypted[16:], key, encryptedKey)
    digest = sha1(decrypted)[:16]    if digest != encryptedKey:        raise ValueError('App Info: bad decrypt key, data not decrypted - maybe has passcode)
    dataLen = int.from_bytes(decrypted[:4], 'little')    return decrypted[4:dataLen]
def createLocalKey(passcode, salt) -> bytes:    iterCount = 100_000 if passcode else 1
    hash = hashlib.sha512(salt + passcode + salt).digest()    key = hashlib.pbkdf2_hmac("sha512", hash, salt, iterCount, 256)    return key
qstream = readFile('key_data')
salt = qstream.readBytes()keyEncrypted = qstream.readBytes()infoEncrypted = qstream.readBytes()
_passcodeKey = createLocalKey(passcode, salt)_localKey = decryptLocal(keyEncrypted, _passcodeKey)