"I'm sure the title of today's post probably put off
more than a few purists who subscribe to the more exact definition
that steganography is "the art of writing in cipher, or in
characters which are not intelligible except to persons who have
the key." If you define steganography that strictly, there can be
no such thing as keyless steganography, except in the land where
the oxymoron is king ;)
"Later in the week, we'll be looking at "really" hiding a
message inside another message (or PDF, or picture, etc, as the
case may be) so that it can't be encoded or decoded without a key.
For now, we're going to look at just how easily one can pass a
message along (inside a bitmap image) without using a key. The
beauty of this method is that it's incredibly easy to implement and
hard to notice if one isn't looking for it."