The mask is unique in that its effects depend on a code that is input by the user via a dialog box that appears when the user clicks the CP Mask button.
When you select CP mask you are asked for a password (or more) this password decides the pattern of block shifting. The CP algorithm splits the selected area into individual 8 × 8 pixel blocks. The password you choose must be only alphabetical characters and must be between 1 and 16 characters in length. It is not case sensitive. Once applied the algorithm switches the red and green channels and applies the Negative mask. It then arranges the block in accordnce to the password you have chosen, rotating some blocks 90° but not all blocks.
Use of the CP Mask can be frowned upon, because without knowing the code it is virtually impossible to unmask the image. Furthermore, it can be difficult to notice when a CP mask has been applied to an image at all, as the scrambled pattern can be mistaken for the pattern provided by more common mixtures of FL Mask and Meko Mask.
The input code may be comprised only of alphabetical characters. Anything else returns an error: "Only Alphabetical Chars. Allowed." Spaces do not cause an error, but are instead ignored: "GMASK WIKI" is the same as "GMASKWIKI". The code is case insensitive.