============ Cryptostream

Cryptostream is a WSGI app serving as a very light security layer to protect files. For example, if a user purchases some software, the store app would use this WSGI app to generate a download URL that is only valid for a certain amount of time.

A typical download works like this:

• As per the Using section below, your app uses encrypt_url() to generate a GET string.
• The GET string is sent to the cryptostream WSGI app.
• Cryptostream uses the X-Accel-Redirect header to pass the file directly to nginx, instead of serving it from within the WSGI app.

Source: https://github.com/duointeractive/cryptostream

Cryptostream is good for...

• Disguising paths to downloads on your protected media server.
• Cases where you're just looking for a deterrent for someone passing out download links to their buddies.

Cryptostream is not good for...

• Cases where absolute maximum security is desired.

Running

Launch the main:app using gunicorn::

gunicorn main:app

Using Cryptostream in your application

Application does two things:

1. Checks a timestamp to make sure the link was recently given to the user.
2. Redirect user to a static URL without giving this URL to the user.

To encrypt a url for cryptostream to decode, do something like this within your app::

>> from cryptostream.main import encrypt_url
>> encrypt_url("/foo/bar/")
'path=SQkADU4QBx0%3D&ts=V11XVVFAVFlaVE9AUg%3D%3D'

Then use these as GET keywords to the url cryptostream is running on.

Configuring Nginx

There are two variables in main.py that control behavior::

# A Plain text encryption key
KEY = 'foobar'  
# Maximum time the link will be alive.
LINK_EXPIRE_TDELTA = datetime.timedelta(hours=4)

Sample Nginx Server Config::

server {
    listen   80 default;
    server_name  localhost;

    access_log  /var/log/nginx/localhost.access.log;

    # Serves up jpegs in my picture directory at root
    location ~ .(jpg|JPG)$ {
        root   /home/dylan/Pictures;
    }

    # Gunicorn running the Cryptostream app
        location / {
                proxy_pass http://127.0.0.1:8000/;
        }
}