#Crux in a nutshell

Crux is a complete system enabling end-users to submit queries for statistics on private data. It is designed with Tor in mind, but it can be easily extended to work with other systems too.

The system currently supports:

• Median
• Mean
• Variance

and other statistics can be added if needed.

For a testing setup we need:

1. An Authority

   To start the relay the terminal command is in the form:

   python authority.py

2. A query processor

   To start the q. processor the terminal command is in the form:

   python processor.py AUTH_IP_1-AUTH_IP_2 RELAY_IP_1-RELAY_IP_2

   An example would be:

   python processor.py 127.0.0.1 127.0.0.1

3. A relay

   To start the relay the terminal command is in the form:

   python relay.py AUTH_IP_1-AUTH_IP_2 RELAY_IP_1-RELAY_IP_2 RELAY_ID NUM_OF_RELAYS

   An example using a dummy dataset would be:

   python relay.py 127.0.0.1 127.0.0.1 0 1

   It should be noted that in its current form the relay component is only able to parse data only from xls files.

4. When all the above components are loaded, the user script can then be used to submit requests in the form:

   python user.py -s "processor_ip" -p "processor_port" --stat "stat_type" "strings" "which specify" "the column in the xls"

   an example would be:

   python user.py -s 127.0.0.1 -p 8888 --stat median "Lone Parents" "Lone parents not in employment" 2011

   The parameters of the statistic (e.g. "Lone Parents" "Lone parents not in employment" 2011) depend on the specific application/data. The details seen here correspond to our testing dataset.

   However, keep in mind that in an actual setup at least 2 (non-actively malicious) relays should be used.

##Requirements The project was developed and tested in python 2.7. Please let me know if it works/or not on a different version.

The following packages are also needed and you should install them if they are not already installed on your system:

• Fabric
• Boto
• petlib
• socketServer
• xlrd
• binascii

Most of them can be installed using pip, but look on their project websites for detailed instructions.

##Future Improvements

• Support other statistics
• Support adding new authorities on the fly
• Django user interface
• Ephimeral Keys