套件： camo (2.3.0+dfsg-1.1)

SSL/TLS image proxy to prevent mixed-content warnings

Camo is an image proxy to prevent mixed content warnings on secure pages.

It should not be installed by an end-user; instead people who operate websites that allow user-specified image embeds by URL can run this as a daemon to proxy such images through their own servers and serve the resulting content over SSL/TLS.

This provides integrity protection and last-mile confidentiality to images, thus preventing a local network attacker from seeing the images you request (allowing for possible disclosure of the content you're viewing) or changing their content (to misinform, confuse, or shock).

It of course does not prevent an attacker from modifying the content or noticing its access if the attacker is in the path between your datacentre and the image source.

However, even in this case, it provides some security insofar as it may prevent the attacker from knowing who is accessing the image.

Using a shared key, proxy URLs are encrypted with hmac so we can bust caches/ban/rate limit if needed.

Features include:

 * Proxy Google charts
 * Proxy images under 5 MB
 * Follow redirects to a configurable depth
 * Proxy remote images with a content-type of image/*
 * Disallows proxying to private IP ranges