MEGA SDK - Client Access Engine

MEGA --- The Privacy Company --- is a Secure Cloud Storage provider that protects your data thanks to end-to-end encryption. We call it User Controlled Encryption, or UCE, and all our clients automatically manage it.

All files stored on MEGA are encrypted. All data transfers from and to MEGA are encrypted. And while most cloud storage providers can and do claim the same, MEGA is different – unlike the industry norm where the cloud storage provider holds the decryption key, with MEGA, you control the encryption, you hold the keys, and you decide who you grant or deny access to your files.

This SDK brings you all the power of our client applications and let you create your own or analyze the security of our products. Are you ready to start? Please continue reading.

SDK Contents

In this SDK, you can find our low level SDK, that was already released few months after the MEGA launch, a new intermediate layer to make it easier to use and to bind with other programming languages, and example apps for all our currently supported platforms (Windows, Linux, OSX, Android, iOS and Windows Phone).

In the examples folder you can find example apps using:

1. The low level SDK:

• megacli (a powerful command line tool that allows to use all SDK features)
• megasimplesync (a command line tool that allows to use the synchronization engine)

2. The intermediate layer:

• An example app for Visual Studio in examples/win32
• An example app for Android (using Java bindings based on SWIG) in examples/android
• An example app for iOS (using Objective-C bindings) in examples/iOS
• An example app for Windows Phone (using Windows Phone bindings) in examples/wp8

MEGAcmd, a higher level command line application that uses the SDK to provide interactive and scriptable access to MEGA, can be found here.

Building

There are two methods - the one we are using now for most platforms is with vcpkg and cmake, and the prior system based on autotools still works for POSIX based systems.

Platform Dependencies

Some dependencies are different for each platform because the SDK uses generic interfaces to get some features and they have different implementations.

• Network (cURL with OpenSSL/c-ares or WinHTTP)
• Filesystem access (Posix or Win32)
• Graphics management (FreeImage or iOS frameworks)
• Threads/mutexes (pthread threads, or C++11)
• Drive Notifications (udev for Posix, WMI/WBEM for Win32, or Apple frameworks)

Building with vcpkg and cmake

This is the method that works for Windows - it also works for other platforms (and for those, autotools is also an option). We use vcpkg, cmake, and provide scripts to build the 3rd party libraries and set up the project.

Build the SDK and 3rdParty Dependencies with vcpkg + cmake

• The steps to do so are already prepared in the build_from_scratch.cmake script. It contains instructions too.
• To get started with it, eg for windows, follow these steps:
  • mkdir mybuild
  • cd mybuild
  • git clone https://github.com/meganz/sdk.git
  • cd sdk\contrib\cmake
  • <on Win, choose VS version by editing vcpkg_extra_triplets\xNN-windows-mega.cmake>
  • cmake -DTRIPLET=x64-windows-mega -DEXTRA_ARGS="-DUSE_PDFIUM=0" -P build_from_scratch.cmake
• Visual Studio solution is generated at mybuild\sdk\build-x64-windows-mega
• That folder contains Debug and Release subfolders which contain build products
• Similar steps work for other platforms too (Linux with triplet x64-linux-mega (including WSL), Mac with triplet x64-osx-mega or arm64-osx-mega).

Building with POSIX Autotools (Linux/Darwin/BSD/OSX ...)

For platforms with Autotools, first set up needed libraries and then the generic way to build and install it is:

sh autogen.sh
./configure
make
sudo make install

Notice that you would need Autotools installed in your system (in Linux this normally entails having autoconf and libtool packages installed).

That compilation will include the examples using our low level SDK (megacli and megasimplesync). You also have specific build instructions for OSX (doc/OSX.txt) and FreeBSD (doc/FreeBSD.txt) and a build script to automatically download and build the SDK along with all its dependencies (contrib/build_sdk.sh)

For other platforms, or if you want to see how to use the new intermediate layer, the easiest way is to get a smooth start is to build one of the examples in subfolders of the examples folder.

All these folders contains a README.md file with information about how to get the project up and running, including the installation of all required dependencies.

Dependencies for POSIX Autotools:

Install the following development packages, if available, or download and compile their respective sources (package names are for Debian and RedHat derivatives, respectively):

• cURL (libcurl4-openssl-dev, libcurl-devel), compiled with --enable-ssl
• c-ares (libc-ares-dev, libcares-devel, c-ares-devel)
• OpenSSL (libssl-dev, openssl-devel)
• Crypto++ (libcrypto++-dev, libcryptopp-devel)
• zlib (zlib1g-dev, zlib-devel)
• SQLite (libsqlite3-dev, sqlite-devel) or configure --without-sqlite
• FreeImage (libfreeimage-dev, freeimage-devel) or configure --without-freeimage
• pthread

Optional dependencies:

• Libraw (libraw-dev, libraw-devel)
• Sodium (libsodium-dev, libsodium-devel), configure --with-sodium
• MediaInfoLib (optional, see third_party/README_MediaInfo.txt)
• libudev (libudev-dev, libudev-devel)

Filesystem event monitoring: The provided filesystem layer implements the Linux inotify and the MacOS fsevents interfaces.

PDF thumbnail generation: The PDFium library is detected automatically by the configure step if installed. There is a helper script located at contrib/build_pdfium to install it in a Linux system (/usr). To download, build and install it in the system, run the following:

cd contrib/build_pdfium
build.sh -b
sudo build.sh -i

Library will be installed under /usr/lib/ and headers under /usr/include/. Once installed, the generated workspace folder could be removed to free up space.

To build the reference megacli example, you may also need to install:

• GNU Readline (libreadline-dev, readline-devel) on Mac, you will probably need to download the source and build it yourself, and adjust the project to refer to that version.

For Android, we provide an additional implementation of the graphics subsystem using Android libraries.

For iOS, we provide an additional implementation of the graphics subsystem using Objective C frameworks.

Usage

The low level SDK doesn't have inline documentation yet. If you want to use it, please check one of our example apps (examples/megacli, examples/megasimplesync).

The new intermediate layer has been documented using Doxygen. The only public header that you need to include to use is include/megaapi.h. You can read the documentation in that header file, or download the same documentation in HTML format from this link:

https://mega.nz/#!7glwEQBT!Fy9cwPpCmuaVdEkW19qwBLaiMeyufB1kseqisOAxfi8

Additional info

Folder syncing

In this version, the sync functionality is limited in scope and functionality:

• There is no locking between clients accessing the same remote folder. Concurrent creation of identically named files and folders can result in server-side dupes.

• Syncing between clients with differing filesystem naming semantics can lead to loss of data, e.g. when syncing a folder containing ABC.TXT and abc.txt with a Windows client.

• On POSIX platforms, filenames are assumed to be encoded in UTF-8. Invalid byte sequences can lead to undefined behaviour.

• Local filesystem items must not be exposed to the sync subsystem more than once. Any dupes, whether by nesting syncs or through filesystem links, will lead to unexpected results and loss of data.

• No in-place versioning. Deleted remote files can be found in //bin/SyncDebris (only when syncing to the logged in account's own cloud drive - there is no SyncDebris facility on syncs to inbound shares), deleted local files in a sync-specific hidden debris folder located in the local sync's root folder.

• No delta writes. Changed files are always overwritten as a whole, which means that it is not a good idea to sync e.g. live database tables.

• No direct peer-to-peer syncing. Even two machines in the same local subnet will still sync via the remote storage infrastructure.

• No support for unidirectional syncing (backup-only, restore-only). Syncing to an inbound share requires it to have full access rights.

megacli on Windows

The megacli example is currently not handling console Unicode input/output correctly if run in cmd.exe.

Filename caveats: Please prefix all paths with \\?\ to avoid the following issues:

• The MAX_PATH (260 character) length limitation, which would make it impossible to access files in deep directory structures

• Prohibited filenames (con/prn/aux/clock$/nul/com1...com9/lpt1...lpt9). Such files and folders will still be inaccessible through e.g. Explorer!

Also, disable automatic short name generation to eliminate the risk of clashes with existing short names.