Feature Request: Shift Cipher with Prepended Key

[JProffitt71]

Right now powers that be can search for encoded keywords and find everyone that mentioned e.g. "landlord" in their comment on their website.

It would be very helpful if the extension optionally prepended a value that offset the encoding/decoding, so that for this one message say "\u{200D}\u{2060}" actually decodes to "a" instead of "m". This would make it much more difficult to search for people mentioning certain keywords.