Protected downloads (hard !)

[EnderW]

Greetings,

First of all, i'd like to apologize for my poor english, which is not my main lenguage, i hope you'll understand the following anyway 🙂

I have to make a protected downloads manager, this is what it means :

• Only the users authorized will be able to download the file.

It may be for an application where you have to pay to download something, or just because i want some users (members for example) to download and not others.

All authorization acesses are already done, so i've come to the point where the user is known to be an authorized user, and will click on the link for downloading the file, and in next page i want to make this user download the file automatically preventing anyone else (not allowed) to do so.

Every file that can be downloaded is kept in a protected directory only readable by the server.

I have thought of some solutions but i didn't find the optimal one yet

1) Copy the file to a non protected directory with a random name and make the user download this new file

Problems :
- It's not that much secure, as you could still download the file if you find a way to know the random name that has been set. (or test everything in the free directory)
- i don't know how to delete the file after it has been downloaded or if the download has failed without having the user to click on a button like "i have finished downloading"

To bypass the first problem, i thought of allowing the download only if noone else is downloading this file already, but again i don't know how to do it and it doesn't solve the second problem

2) Using a client_sided program (like a java function or a "beurk" activeX control) that the user has to download (or that will install automatically on agreement) to be able to download on the website.
This last option seems to be the best one, but in fact i have no knowledge of this type of programming, so if anyone knows how it works, or how it could work i could start working on it with at least some basis. (i understand this is not related directly to php programming but as it would be included in a php code i hope someone can help)

That's all so if anyone has a solution or can help with the ones above i have already thought of it would be great !
Please understand that solutions known as "anti-leech" where url is just hided to the user is NOT an acceptable solution for me, it's only poor security level and will not prevent "intelligent" users to download the file...

Thank you
EnderW

[Jayson]

You should look into using a database. You can keep track of what files each user has permission to download. The files would be downloaded through a script, and there you would check if that person has access to the file or not and either give them the file's contents or give them an error.

[EnderW]

Greetings,

I think my bad english made you misunderstand my problem, or i don't understand your answer.

My problem isn't to know if the user is authorized or not, i have a big database (well i hope not too big 🙂 ) with members tables, forum tables, news tables, stats table .. and i have no problem at the point of the script where the user should download to know if he is allowed to do so.

In fact, my only problem is what you says as "The file would be downloaded through the script"
If the file is in a free directory (i mean permissions are set to public can read) then anyone not authorized could download the file by typing its url in his browser.

Please refer to my first post for the start of solutions i'm thinking of, and thanks anyway for your answer.

Can anyone help ?

EnderW

[EnderW]

In fact i think i was just thinking of things way too complicated before looking at what is evident.

The solution seems simply to send the headers of the file and then send the file trhough the script (like you sais Jayson 🙂 ) using readfile().

The file would still be in a protected directory but will be sent to the user.

Correct me if i'm wrong, but i'm gonna try this now.

See ya
EnderW

[Jayson]

Originally posted by EnderW
The file would still be in a protected directory but will be sent to the user.

Right. Maybe I wasn't making it clear in my post, but that's what I meant. You don't reveal the directory to the users. In fact you can even put it higher than your document root, so it isn't even accessible. You read in the file through the script if the person has permission to download it, and send it down to them.