Thanks for all your replies. Spasibo :)

I have some (strong) requirements like to not modify the application code or to do as few changes in the platform's configuration/architecture as possible. Thus I'm using Igor's example that seemed to me the best choice for migration from Lighttpd to Nginx. I'm trying to make the following configuration works :

Secured link :
http://secure.domain.com/get/24b9cb61c9c2c9070038aceaaf7bae5a/4d63842e/2/H264-384x288/04/85/3120485.h264

*******************************************************
Configuration :

server {
server_name secure.domain.com;
root /var/www;

location /get/ {
location ~ ^/get/([\w\-=]+)/(\w+)(/.+)$ {

root /mnt/medias;

secure_link $1,$2;
secure_link_md5 $3.$2.$mysalt

if ($secure_link = "") { # no valid
return 403;
}

if ($secure_link = "0") { # expired
return 410;
}
}

return 404;

error_page 403 /forbidden.html;
error_page 404 /not_found.html;
error_page 410 =403 /link_expired.html;
}
}

*******************************************************

After trying to access the link I always got this into my error.log :

2011/02/22 10:50:32 [error] 26143#0: *1 open() "/var/www/forbidden.html" failed (2: No such file or directory), client: 192.168.156.11, server: secure.domain.com, request: "GET /get/24b9cb61c9c2c9070038aceaaf7bae5a/4d63842e/2/H264-384x288/04/85/3120485.h264 HTTP/1.1", host: "secure.domain.com"


As far as I understand I got a "403" everytime I'm trying to validate the URL. That means $secure_link is empty and I don't know why... Of course, I'm not using an "epoch Unix time" in the link so I modified it to be able to send a date in this format but I keep having the same error into my log.

It will be (really) better if can keep my actual link format with the expiration time given in hex not in epoch but If there is no other solution, I will change the application's code.

Thanks for your answers.
Regards,

Thomas S