Click File 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.