问题:

Is it possible download a file in an AIR application, store it on the user's system, and prohibit access to the files by applications other than the one with which it was downloaded?

回答1:

Certainly not easily done on Windows. You might have better luck encrypting it's contents.

EDIT: Creating a file not accessible by other programs is very virus-like behavior.

回答2:

Encryption is indeed probably the way to go. AIR does have a handy encrypted local store which should simplify this approach for you:

http://livedocs.adobe.com/flex/3/langref/flash/data/EncryptedLocalStore.html

回答3:

Your best bet is to store the contents of the file in the EncryptedLocalStore or a local shard object. While you can store the downloaded file in a directory on the user's file system, you aren't going to be able to prevent it from being accessed by other applications (or the user) on the system. That's a security issue because that's how a lot of viruses work.