Martin DENIZET

Based on: https://community.letsencrypt.org/t/how-to-update-python-and-installing-lets-encrypt-client-on-debian-6-squeeze/7118

Install some dependencies:

apt-get install build-essential python-pip git libssl-dev libffi-dev python-dev
pip install pythonbrew
pythonbrew_install
source "$HOME/.pythonbrew/etc/bashrc"

Updating Python to version 2.7.10 :

pythonbrew install 2.7.10
pythonbrew switch 2.7.10
pythonbrew use 2.7.10

Installing some Python dependencies:

pip install virtualenv
pip install pyopenssl ndg-httpsclient pyasn1
pip install cryptography

At this point point if pip needs an update, need to re-install it with easy_install

wget https://raw.githubusercontent.com/pypa/setuptools/bootstrap/ez_setup.py -O - | python
wget https://raw.githubusercontent.com/pypa/setuptools/bootstrap/ez_setup.py --no-check-certificate -O - | python
easy_install pip
/root/.pythonbrew/pythons/Python-2.7.10/bin/pip virtualenv
/root/.pythonbrew/pythons/Python-2.7.10/bin/pip install virtualenv
/root/.pythonbrew/pythons/Python-2.7.10/bin/pip install pyopenssl ndg-httpsclient pyasn1

Installing LetsEncrypt Client:

git clone https://github.com/letsencrypt/letsencrypt
cd letsencrypt
./letsencrypt-auto

Done!