A guide through the Syncrypt client source code
This is a quick writeup of the Syncrypt client internals, so that you can quickly get a grip on how it works. It is not complicated. We will start from the inner core machinery and work ourselves outwards.
Before digging through the source code, make sure that you've read the general information about the Syncrypt encryption.
At the heart of the Syncrypt client is a tiny abstraction dubbed
Pipes. Pipes can be seen as operators or functions on streams and operate
asynchronously thanks to the
asyncio framework from Python 3.
There are Pipes for various functions, for example IO (reading and writing files), cryptographic functions (symmetric and asymmetric encryption and decryption), compression, and other things like buffering.
Pipes can be chained together using the
>> operator. In the following
example, the contents of a file will be compressed and a hash will be
calculated from the compressed content.
hash_pipe = FileReader('my_file.txt') >> SnappyCompress() >> Hash('sha256') hash_pipe.consume()
You can explore all available Pipes in the directory
To see these Pipes in action, you can take a look at the
A Bundle basically describes a file with additional information, like the file
size and the content hash.
A Bundle has the functions
write_encrypted_stream, which will return a Pipe and consume a Pipe,
respectively. Equipped with our Pipes toolkit, we can now easily reason
about how an encrypted stream is constructed:
def read_encrypted_stream(self): return FileReader(self.path) \ >> SnappyCompress() \ >> Buffered(self.vault.config.enc_buf_size) \ >> PadAES() \ >> EncryptAES(self.key)
Vault class represents a single folder and has functionality to manage its
config, identity and bundles.
Currently there only exists a single storage backend implementation.
This can be found in the file
backends/binary.py and is the implementation
of the binary Syncrypt client/server communication protocol. We won't go into
details here as they can be discovered by reading the source code, but the
basic principle of this communication protocol is that the client sends a
serialized command and the server responds with a serialized response.
The serialization format that is currently used is BERT (Binary ERlang Term).
Note that you can turn on the
BINARY_DEBUG flag in order to see the whole
serialized and unserialized communication if you are interested.
SyncryptApp object is the outer shell of the Syncrypt client.
It basically calls the backend and ties together the different models.