This tab allows you to set the workbook security
and also the security around macros and scripts
which can and do carry malicious viruses.
The top two boxes set password encryption for
the workbook and/or a password to allow a user
to share the workbook. A password can be up to
15 digits long including letters and numbers and
is case-sensitive. In the sharing section,
unless the user has the password, they will be
able to change the workbook, but unable to save
it as the same name, the same is the case if the
read-only flag is set, but in this case it is
for all users, whether they have the password or
not.
The 'Advanced...' button displays settings
for various different types of encryption and
the 'Digital signatures...' button allows you to
see a list of people who have digitally 'signed'
the document with a security certificate and
allows you to add yours. Again, this helps in
stopping the workbook from being accessed,
changed and distributed maliciously.
Checking the 'privacy' box will remove all
the user details, that would normally be visible
in the 'Properties'
dialog of the workbook when saving. If you have
ActiveX controls or code in the workbook, you
will get the dialog below (That's a great
dialog!) as there are certain pieces of user
information Excel cannot remove.
Under 'macro security', you can set the level
at which macros and code in workbooks is allowed
to open. There are four settings: (See below)
1) Very High
Only workbooks containing macros from
companies/people marked as 'trusted' will be
permitted. These appear in the second tab
'Trusted Publishers'
2) High (Default in Excel 2003)
Excel disables all macros and no warning is
given, unless the macros are signed with a
special certificate, 'whether trusted or not).
As this is now the installed default, if you
have a book that contains code, but that does
not work, this is likely the cause.
3) Medium (Default in 2000 and XP)
Prompts the user as to whether macros in the
workbook should be enabled or not, disabling
will obviously stop any code from working,
enabling allows code to run, but unless the
workbook is from a trusted source, you are at
risk that code may be malicious. Remember,
workbooks can have event code (e.g.
workbook_open()), that fires immediately, so if
you are not sure, perhaps best to select
disable. The dialog below shows the selections.
You can prevent this dialog from showing at
all in three ways:
a) Files saved and loaded as add-ins do not
display this warning.
b) Files written in C+ as XLLs do not display
this warning.
c) Macros which are digitally signed do not
display this warning.
Sometimes users believe they have removed all
code from a workbook, but the dialog keeps
showing, you can find how to resolve this issue
here.
4) Low
This setting will open workbooks that contain
macros, with the macros enable without warning
the user. You should use this setting with
caution. |
