If I understand your preperly...
I have not any information about your possible values of entered strings... If you know about list of possible characters in text, then you can change it after entering string. You can use global replacing like this:
'|' -> '<vertical-line>'
'.' -> '<dot>'
This replaces is true only if user can't entering '<vertical-line>' or '<dot>'... You can use more strange replaces like '|'->'asdqwezxc'
or any other simplier string-code.
But you must before this string output use reverse decoding of this values...
May be in some situations this method will be usefull...