The Windows XP Professional operating
system allows for both compression and encryption natively
within the operating system by setting given attributes on
the files and folders. Both of these functions are
mutually exclusive of each other and only one or the other
can be enacted on a particular file or directory at any given time.
[NOTES FROM THE FIELD] - What
you can do is compress an entire directory and all of the
files and folders within that directory and then go in and
elect to encrypt select files which will remove the
compression bit from those selections that will be come
encrypted. A file or folder cannot be both encrypted and
compressed at the same time under Windows 2000 or XP
Professional natively by the operating system itself.
There is a Compressed Folders
feature within Windows XP Professional which provides the
ability to create compressed folders and view their contents
much in the manner that many other programs such as PKZip
and WinZip perform. This article deals with the operating
system / attribute driven level of compression and not this
particular utility.
It is important to note that
compressed folders of this nature, created through the use
of the Compressed Folders feature within Windows XP
Professional, CAN be encrypted on NTFS partitions and CAN be
compressed (only) on FAT16 and FAT32 partitions.
You can compress a folder by selecting
the folder, right clicking it and choosing Properties. On
the GENERAL tab of the properties page you would select the
Advanced button in order to bring up the Advanced Attributes
page, as shown below.
On the Advanced Attributes page you
would go down to the Compress or Encrypt attributes section
where you can choose one checkbox to compress the contents
or the other to encrypt them.
[NOTES FROM THE FIELD] -
Strangely enough, the options to target are check boxes,
which normally denote the ability to choose more than one
selection. (Radio buttons are normally used in a situation
where only one option from a number of given ones can be
selected.) Regardless of which, if you attempt to select
both, you will find that your second choice in this section
undoes your first selection.
I think the decision to program this
property page in this way stems from the fact that you
cannot unselect a radio button by clicking on it a second
time as you can a checkbox. (This is just my thought on
this. This is not backed up by any facts.) If you want to
make a folder and the contents "normal" by neither
encrypting them nor compressing them, you'd clear the
checkboxes.
Once you elect to compress the folder
by selecting that checkbox you would click OK and it would
seem as if nothing has happened, and actually, nothing has.
Until you click APPLY or OK to the main property sheet, you
will not be given any further options for this operation.
At that time, the next options are
available as shown below.
If you elect to apply changes to the
folder only, only the folder itself will become compressed. What
this means is that anything currently in the folder will
keep it's current compression state. (In most cases this
would mean that the files and other folders within that
folder will remain uncompressed.) Anything added to that
folder from that point forward will become compressed as it is copied to or moved to
the folder.
[NOTES FROM THE FIELD] - Any
encrypted file that is moved to or copied to that compressed folder
will remain encrypted and will NOT become compressed and
hence unencrypted. If the encrypted file that was moved to
that folder is right clicked and has the encryption
attribute removed it will NOT become compressed
automatically.
The only way to compress that file
is to individually right click it and choose to compress it
or to MOVE it out of and then back into the folder. Simply
copying it out to a temporary location and then back in with
the OVERWRITE option will NOT cause it to become compressed
even if changes were made to the copied out version.
This means that if an encrypted
document is unencrypted in a compressed folder it will be in
a normal state. If another copy of that document exists
somewhere else on the system and it is in a compressed state
and editing is performed on it and then saved and then that
compressed and updated copy is copied over the older
version, that older version will still be uncompressed in
that folder that is supposed to compress all new files that
are copied in. The updates to the text will be present, but
the file will still be uncompressed.
This is because the attributes to
the file are not carried over with the changes to the file
itself.
This also works for the reverse,
from not compressed to compressed.
If you elect to apply changes to the folder and all of the
files and subfolders contained within the folder, they will
all become compressed.
If you elect to remove compression from the folder itself and
choose to make the attribute changes to the folder only, all
the files in the folder that were compressed before will
remain compressed as you move them around the local system.
When you effect changes to the folder and all of the files
subfolders contained within, all of the files will be come
uncompressed.
[NOTES FROM THE FIELD] - If there is a file within
the folder that is to be uncompressed that is in an
encrypted state, it will stay encrypted as the encrypted
attribute of that file is not affected by the clearing of
the compression attributes of the other files around it and
the fold it's in.
You can select to view compressed and encrypted files in
different colors so that you know the state of the file by
quickly looking at it.
[NOTES FROM THE FIELD] - In the example above, the
file denoted in blue lettering is compressed and the one in
green lettering is encrypted. This can be set by going in to
the Windows Explorer and choosing Tools and then Folder
Options.
On the View tab of the pop up box is where you would
select the Show encrypted of compressed NTFS files in color
checkbox to enable this feature.
If you copy an attribute set compressed file to a
FAT16 or a FAT32 partition or to a floppy disk, it will lose its
compression attribute.
The overall rules for compression are
as follows:
Copying a file within the same NTFS volume
causesthe file to inherit the compression state of
the target folder. When you copy a compressed file to an
uncompressed folder, the file is automatically
uncompressed.
Moving a file or folder within the same NTFS volume
causesthe file or folder to retain its
original compression state. When you move a compressed
file to an uncompressed folder, the file remains
compressed.
Copying a file or folder from one NTFS volume to
another causesthe file or folder to inherit
the compression state of the target folder. When you copy
a compressed file from one NTFS volume to another,
where the target folder is uncompressed, the file is
automatically uncompressed.
Moving a file or folder from one NTFS volume to
another causesthe file or folder to inherit
the compression state of the target folder. Windows XP
Professional treats a move (cut and paste) as a copy and a
delete, the files inherit the compression state of the
target folder.
Moving or copying a file or folder to a FAT16 or
FAT32 volume - Windows XP Professional supports
attribute driven compression only on the NTFS file system,
so when you move or copy a compressed NTFS file or folder
to a FAT volume, (12, 16 or 32) Windows XP Professional
will automatically uncompress the file or folder. If you
need to maintain some level of compression in this
scenario you can use the Compressed Folders feature within
Windows XP Professional.
Moving or copying a compressed file or folder to a
floppy disk or other removable media - Windows XP
Professional supports attribute driven compression only on
the NTFS file system, so when you move or copy a
compressed NTFS file or folder to most types of removable
media, Windows XP Professional will automatically
uncompress the file or folder because most forms of
removable media do not support the NTFS file system. If
you need to maintain some level of compression in this
scenario you can use the Compressed Folders feature within
Windows XP Professional.
Best practices state that you should
not attempt to set the compression attribute on software
compressed files and folders such as ones set by PKZip
and/or WinZip or folders that are compressed by using the
Compressed Folders feature within Windows XP Professional
because the operating system will attempt to further
compress the files. This will not yield any additional
savings of space on the hard drive and will unnecessarily
burn CPU cycles in the process.
You should also attempt to compress
data that is not often modified, as there is some system
overhead to uncompressing the files to open them for editing
and then compressing them again. This also is the same for
files that are moved or copied often. When a compressed file
is copied, it is uncompressed, copied, and then compressed
again as a new file (depending on its final destination as
outlined above.)
[NOTES FROM THE FIELD] - What you can do is compress an entire
directory and all of the files and folders within that directory and then go in
and elect to encrypt select files which will remove the compression bit from
those selections that will be come encrypted. A file or folder cannot be both
encrypted and compressed at the same time under Windows 2000 or XP Professional
natively by the operating system itself.
There is a Compressed Folders feature within
Windows XP Professional which provides the ability to create compressed folders
and view their contents much in the manner that many other programs such as
PKZip and WinZip perform. This article deals with the operating system / attribute
driven level of compression and not this particular utility.
It is important to note that compressed
folders of this nature, created through the use of the Compressed Folders
feature within Windows XP Professional, CAN be encrypted on NTFS partitions and
CAN be compressed (only) on FAT16 and FAT32 partitions.
You can encrypt a folder by selecting the
folder, right clicking it and choosing Properties.
On the GENERAL tab of the properties page
you would select the Advanced button in order to bring up the Advanced
Attributes page, as shown below.
On the Advanced Attributes page you would go
down to the Compress or Encrypt attributes section where you can choose one
checkbox to compress the contents or the other to encrypt them.
[NOTES FROM THE FIELD] - Strangely enough, the options to target are
check boxes, which normally denote the ability to choose more than one
selection. (Radio buttons are normally used in a situation where only one
option from a number of given ones can be selected.) Regardless of which, if
you attempt to select both, you will find that your second choice in this
section undoes your first selection.
I think the decision to program this
property page in this way stems from the fact that you cannot unselect a radio
button by clicking on it a second time as you can a checkbox. (This is just my
thought on this. This is not backed up by any facts.) If you want to make a
folder and the contents "normal" by neither encrypting them nor
compressing them, you'd clear the checkboxes.
Once you elect to encrypt the folder by
selecting that checkbox you would click OK and it would seem as if nothing has
happened, and actually, nothing has. Until you click APPLY or OK to the main
property sheet, you will not be given any further options for this operation.
At that time, the next options are available
as shown below.
If you elect to apply changes to the folder
only, only the folder itself will become encrypted. What this means is that
anything currently in the folder will keep its current state which is
unencrypted. Anything added to that folder from that point forward will become
encrypted as it is copied to or moved to the folder.
Once you hit OK you will see the progress of
the encryption attribute being set on all the files and subfolders as you have
selected.
[NOTES FROM THE FIELD] - Any encrypted file that is moved to or
copied to a compressed folder will remain encrypted and will NOT become
compressed and hence unencrypted.
If the encrypted file that was moved to that
folder is right clicked and has the encryption attribute removed it will NOT
become compressed automatically.
The only way to compress that file is to
individually right click it and choose to compress it or to MOVE it out of and
then back into the folder AFTER the encryption bit has been turned off for that
file. Simply copying it out to a temporary location and then back in with the
OVERWRITE option will NOT cause it to become compressed even if changes were
made to the copied out version.
This means that if an encrypted document is
unencrypted in a compressed folder it will be in a normal state, (not encrypted
nor compressed). If another copy of that document exists somewhere else on the
system and it is in a compressed state and editing is performed on that copy
and then saved at that location of the hard drive and then that compressed and
updated copy is copied over the older version, that older version will still be
uncompressed in that folder that is supposed to compress all new files that are
copied in. The updates to the text will be present, but the file will still be
uncompressed.
This is because the attributes to the file
are not carried over with the changes to the file itself.
This also works for the reverse, from not
compressed to compressed.
If you elect to apply changes to the folder
and all of the files and subfolders contained within the folder, they will all
become encrypted.
If you elect to remove encryption from the folder itself and choose to make the
attribute changes to the folder only, all the files in the folder that were
encrypted before will remain encrypted and if you copy them within the
partition those individual files will remain encrypted. All new files copied to
or created in that folder will no longer have the encryption bit set.
When you effect changes to the folder and
all of the files subfolders contained within, all of the files will become
decrypted.
[NOTES FROM THE FIELD] - If there is a file within the folder that is
to be uncompressed that is in an encrypted state, it will stay encrypted as the
encrypted attribute of that file is not affected by the clearing of the
compression attributes of the other files around it and the fold it's in.
You can select to view compressed and encrypted files in different colors so
that you know the state of the file by quickly looking at it.
[NOTES FROM THE FIELD] - In the example above, the folders denoted in
blue lettering are compressed and the ones in green lettering are encrypted.
This can be set by going in to the Windows Explorer and choosing Tools and then
Folder Options.
On the View tab of the pop up box is where
you would select the Show encrypted of compressed NTFS files in color checkbox
to enable this feature.
If you copy an attribute set encrypted file
to a FAT16 or a FAT32 partition or to a floppy disk, it will lose its
encryption attribute.
Strangely enough, when you perform this same
action under Windows 2000 you will not receive this message. You will simply be
able to perform your action without the warning.
The overall rules for encryption are as
follows (and they are different than compression):
When moving or copying a file within the same NTFS volume an encrypted file will not inherit the
encryption state of the target folder when that folder is unencrypted. When
you copy or move an encrypted file to an unencrypted folder, the file is
still encrypted. If you have enabled a folder to encrypt files and you
move or copy an unencrypted file to it, it will become encrypted at that
point.
When copying or moving a file or folder from one NTFS volume to
another an encrypted
file will not inherit the encryption state of the target folder when that
folder is unencrypted. When you copy or move an encrypted file to an
unencrypted folder, the file is still encrypted. If you have enabled a
folder to encrypt files and you move or copy an unencrypted file to it,
across partitions, it will become encrypted at that point.
Moving or copying a file or folder to a FAT16 or FAT32 volume - Windows XP Professional supports
attribute driven encryption only on the NTFS file system, so when you move
or copy an encrypted NTFS file or folder to a FAT volume, (12, 16 or 32)
the encryption attribute will be lost.
Moving or copying a compressed file or folder to a floppy disk or
other removable media - Windows
XP Professional supports attribute driven encryption only on the NTFS file
system, so when you move or copy an encrypted NTFS file or folder to most
types of removable media, the encryption attribute will be lost because
most forms of removable media do not support the NTFS file system.
If you should remove encryption from the
parent folder only, all the files and subfolders remain encrypted and any new
files or folders moved, copied or created in the parent folder will be in an
unencrypted state.
The unencrypted folders are shown in black text.
If you have any questions, comments or
even constructive criticism, please feel free to drop me a
note.
