Playing with Weave from Mozilla Labs

by Tarek Ziadé

Mozilla Labs has launched an interesting project called Weave some times ago. The idea is to provide an online service where your Firefox instance can save personal data, like bookmarks or passwords. You can grab a Firefox Add-On here and get started :

Weave Logo

The personal data is encrypted by Firefox using a scheme based on AES 256 and private/public keys. See for more details.

The Weave protocol is quite simple and is documented here :, and I have seen some Python implementations around for the server-side. Although Mozilla’s implementation for their Firefox service looks like it’s in PHP right now.

Mozilla also provides a small Python client for the protocol, which can be used to get and set data to a Weave server:

I was curious about Weave so I started to play around with the Python client, and ended up cloning it on Bitbucket, to add a few things to try it out. The original code in Mozilla’s repository is not packaged (yet) and you just get a few Python modules. Although it has a command line that will let you grab some data from the server, but I wanted to try it out from my code.

So I’ve made it an installable Python package in my clone so I could install the client with Pip or easy_install.

Then I wrote a small class to try it to get my Firefox bookmarks:

import json
from weave.client import WeaveStorageContext, WeaveCryptoContext


class WeaveClient(object):

    def __init__(self, user_id, password, passphrase, server=_DEFAULT_SERVER): = WeaveStorageContext(user_id, password, server)
        self.crypto = WeaveCryptoContext(, passphrase)

    def _deserialize(self, payload):
        return json.loads(self.crypto.decrypt(json.loads(payload)))

    def get_bookmarks(self):
        for bookmark in'bookmarks'):
            bookmark = self._deserialize(item['payload'])[0]
            if bookmark['type'] != 'bookmark':
            yield bookmark['title'], bookmark['bmkUri']

if __name__ == '__main__':
    client = WeaveClient('tarek.ziade', 'password', 'passphrase')
    for title, url in client.get_bookmarks():
        print title, url

Here, a storage context class and a crypto context class are created with my login information, and the get_items() API gives me back a list of encrypted bookmarks. Weave organizes its data into collections, and bookmarks is just a label for one collection. There are other collections (see, but Weave could be used to store and retrieve any kind of data.

If you want to replay my example, or play with the client, you can install it using my bitbucket repository like this:

$ pip install
$ easy_install install

Beware that this is not a release, just my custom clone :). But I’ll probably ping the author to see if he has any interest in packaging his modules like I did, so we get it at PyPI.

What I am really looking forward about Weave now is how the project is going to grow and securely handle millions of user’s data. This will probably end up in a very interesting infrastructure, with some similarities with projects like Dropbox or Tahoe.