We currently have a requirement to scan documents into Acrobat X & require the PDF's to only be read/printable. Having password protected files is not within our scope & apparently this was possible on earlier versions.
The only way I can see this function to be possible is to add a password or have a certificate which is not the desired method.
Yes, use password security.
No, don't set an open password.
The password you need to set will be a "control" password, which needs to be quoted only to change security options at a later date.
Take care to read and understand the full implications of the warning.
Note that "read only" properly means "this file can be read and copied but this (original) file cannot be changed." This is nothing to do with PDF security, but is done with system security. Such a "read only" file can be freely changed if you work on a copy.
If proving authenticity is important, look at Digital Signatures instead.
Thanks so much.
I'll let the client know the appropriate steps to password protect the editing of the file.