You can also have a separate set of pads that decrypt the messages to something entirely different from the real messages. I'm not aware of another crypto system that allows for this. Here's an example:

    $ padder -d -m c2wrbumxvj8gob34mxn46pxg29a6kxnwfhcaam3en-hr-2v -p ryxrvqnlhz04icqq6eg56cuhg10vlx5dff3ba44wg6ic-kd

PlainText: we-are-moving-north-and-will-attack-at-the-pass

    $ padder -d -m c2wrbumxvj8gob34mxn46pxg29a6kxnwfhcaam3en-hr-2v -p zifs6d9dgk36k94m9d5x77jhj277ip59gw9btmv4j7in-kc

PlainText: our-group-fled-south-to-the-city-we-sailed-east