How to secure PDF files

all you have to do is set proper NTFS security on your network,,, that will work 100% regardless of the filetype or extension.  IE check the security on the file by going to the properties of the file.

Yes, I can set up NT folders security, but I don't want create NT local account for each users.

so you are asking how to password protect a file then basically, without using NTFS secuirty then right?

What do you mean by password protection? All the users share the same password?

Thanks.

lets get to the root of the problem,, you say that you check the users login info with an ASP script.  what do you mean exacly?  where are the usernames/passwords stored? in a database you created or do you use an ASP script to have them all log into AD with the same account?

The usernames/passwords are stored in Text file.

ok,, so you have an app that basically is a portal that lets users into a separate portion of your website.... and from there im not sure which NTFS account they are using (probably the built in IUSER account which is for anonymous IIS access)  It is my guess that anyone could get to these URLs without any username/password at all.  But my point is, withough NTFS secuirty set up, you users will ALWAYS be able to access any file once they get past your ASP username/password. Especially if they all log in with the same username/password like you mentioned..... if they are all loging in with the same username/password how is the server supposed to know who should get to which files??  I know that is not the answer that you are looking for but it is the right answer and the easiest and most secure way to set up security.  Its built into the OS and is VERY easy to set up.

The text file store multiple user names. My Asp run a COM, it first check weather the user name exist in the text file then use COM the authenticate with LDAP server.

Are you saying it can't be done without using NTFS security(folder permission)?

Thanks.