Camo is all about making insecure assets look secure. This is an SSL image proxy to prevent mixed content warnings on secure pages served from GitHub.

This project is a lightweight PHP version of Camo.

Camo supports two distinct URL formats:

https://example.org/camo.php/<digest>?url=<image-url>
https://example.org/camo.php/<digest>/<image-url>

The <digest> is a 40 character hex encoded HMAC digest generated with a shared secret key and the unescaped <image-url> value. The <image-url> is the absolute URL locating an image. In the first format, the <image-url> should be URL escaped aggressively to ensure the original value isn't mangled in transit. In the second format, each byte of the <image-url> should be hex encoded such that the resulting value includes only characters [0-9a-f].

You only need to upload the file to your web server and put your custom shared key in SERVER_KEY constant.

Apache configuration can be used to delete the file name in URI (https://example.org/ instead of https://example.org/camo.php/) :

RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([0-9a-f]{40}/?[0-9a-f]*/?)$ camo.php/$1 [L,NC]

Configurations are made in constants at the begining of the file :

• SERVER_KEY : The shared key used to generate the HMAC digest (same as CAMO_KEY in original camo project).

• Ruby - https://github.com/ankane/camo
• PHP - https://github.com/willwashburn/Phpamo