ClickFile
menu Save
As.At the Command prompt, enter
saveas.
In the Save Drawing As dialog box, before saving the file,
click Tools menu Security Options.
In the Security Options dialog box, Password tab, enter a
password.
To encrypt drawing properties, such as the title, author,
subject, and keywords, click Encrypt Drawing Properties.
Click OK.
In the Confirm Password dialog box, enter the password you
used. Click OK.
WarningIf you
lose a password, it is not recoverable. Before you add a password
to a drawing, you should create a backup that is not protected with
a password.