How to detect if a Word document is password protected before uploading the file to server?

Question

I am working on a website, which allows users to upload different file formats. We need to restrict the user from uploading password protected files.

Is there a way

Answer 1

Sorry I'm a bit late to the party here. As I don't yet have 50 reputation I can't comment on Tomasso Belluzo's answer, but as I implemented it I found the following:

1. To get the prefix I use Encoding.UTF7.GetString
2. To check for "EncryptedPackage" I use Encoding.Unicode.GetString which obviates the need to remove all the \0s