Version 0.4

Jochen Skulj, jochen@jochenskulj.de

There are a lot solutions to share files among different computers. You can use removable media, set up an own server or use cloud services like DropBox or UbuntuOne. Using cloud services is probably the easiest approach since it is easy to set up, easy to use and cheap - if not even free at all.

But are they secure? Can you use these services to share personal documents or private data? Of course, all service providers claim to be secure and to encrypt your date. But since in most cases you don't know how your data is encrypted, where the data will be stored and how the keys to decrypt your data are managed, it seems to be a little risky to trust these providers entirely.

The only advisable way to usage cloud storage services is to encrypt your data locally on your computer before it is transmitted to the cloud. cryptbox is designed to be an easy to use tool that enables everyone to encrypt personal to use cloud services in a more secury way.

cryptbox is a GTK-based application for GNU/Linux written in Python. It synchronizes the files from a given source directory with a destination directory. During the synchronization processes the files are automatically encrypted and decrypted. Encryption is implemented by using AES.

With cryptbox you can locate the destination directory in a directory that is shared by a cloud service and place the files, you want to share in your source directory. By using cryptbox in this way you can use cloud services with your own encryption.

cryptbox is a Python application designed to run under GNU/Linux and GNOME. it uses Couch DB and python-keyring. On Debian-based systems you should execute

sudo apt-get install couchdb python-keyring

to install the required packages.

Use following commands to download cryptbox from the Git repository and install it:

git clone https://github.com/joskulj/cryptbox.git
cd cryptbox
sudo python setup.py install

You can use cryptbox in two different ways. You can either run cryptbox as a background task within your user session or you can upload and download files by executing seperate commands. If you run cryptbox as a background task cryptbox will syncronize the files in the source and destination directory each 10 seconds. Using the upload and download commands gives you more control when and how the files are synchronized. You may use these commands within your own shell scripts or cron jobs.

In each case of usage you have to setup cryptbox first.

Within the setup you have to specify the source directory and the destination directory. To do this, please execute following command:

cryptbox-runner --config

A GTK dialog will open that allows you to choose the source directory and the destination directory. The source directory is the place where you store the files you want to share. These files will be synchronized and encrypted to files in the destination directory. You should place the destination directory on a sharable resource like your Dropbox folder, a network drive or a removable device.

The config dialog allows you to set up a password salt and the hash count for recursive password hashing. Both configuration entries makes storing passwords more secure. cryptbox needs to store password hashes to check the password at the login. Although cryptbox uses SHA-512 the password hashes may be the target of brute force attacks. A password salt and recursive hashing makes cracking password hashing far more difficult. So it is very recommended to use this options.

Please note that changing password salt and hash count affects the encryption of files. So you should not change these values by using the configuration dialog but use the option for changing the password.

If you use cryptbox for the first time, you have to set up a new password. A dialog opens that asks you to enter and repeat the new password. Please note that currently there is no option to change the password. This feature will be implemented in the future.

After the password is set you have to enter the password each time cryptbox is started or a cryptbox command is executed. You have the option to store the password in your keyring, so you can start cryptbox without any user interaction.

To start cryptbox execute:

cryptbox-runner --start

This command is designed to run cryptbox as a background task. Therefore it is recommended tp set up cryptbox as a start up application using gnome-session-properties.

While cryptbox is running, source and destination diretory are synchronized each 15 minutes. The actions performed by cryptbox are logged in

~/.cryptbox.log

Please note that the log file is written with some delay. To watch the complete log file you should stop cryptbox.

You can stop cryptbox with following command:

cryptbox-runner --stop

The cryptbox synchronization consists of two steps: uploading file from the source directory to the destination directory and downloading files from the destination directory to the source directory

You can perform these steps separate by executing the commands

cryptbox-runner --upload

and

cryptbox-runner --download

These commands can not performed if cryptbox is already running in the background. In this case a message text will be shown and you have to stop cryptbox first.

When executing these commands the performed actions will be printed on stdout and also logged in the cryptbox log file.

To change the password for encryption the files you should invoke

chryptbox-runner --new-password

It opens a dialog where you have to enter the new password twice. Additionally you can set up a password salt and the hash count for recursive password hashing.

After you entered the new password, cryptbox will re-encrypt and upload all files. You should stop and restart cryptbox instances on other machines to login with the new password.

Besides the primary commands the are some utility options. Some of them requires the cryptbox task to be stopped. Following utility options are implemented:

cryptbox-runner --src-list

This option prints out the meta information of the files in the source directory.

cryptbox-runner --dest-list

This options prints out the meta information of the files in the destination directory.

cryptbox-runner --purge

This option deletes all files in the destination directory that are marked as deletes. This is useful to save filespace. It requires to stop cryptbox first.

Additional to all options described above you can use the --debug option. This options logs debug information that are more detailed than the standard log information. The debug information will be saved in a separate debug file:

~/.cryptbox.debug