I was amused by the suggestion of sending a secret message written on shaven head of messenger, who then could not be sent into enemy territory until his hair had re-grown. By that time the message would be a bit stale, don't you think?
I also think the idea of reducing size of message by repeated use of photocopier is hardly practical. The resolution of a photocopier is inadequate for that job.
I remember a scheme that involved dyeing a thread with bands in Morse code or soemthing like that, and then knitting it into part of a garment.
AnnaStrophic ought to be able to describe other methods. Below is what wordsmith wrote, and something i found on Internet.

steganography (ste-GUH-nog-ruh-fee) noun

Secret communication by hiding the existence of message.

A couple of examples of steganography: shrinking the
secret text (by repeated use of a photocopy machine) until
it's the size of a dot and then putting it in an unsuspected
place, such as on top of a letter i in some innocuous letter.
Second, shaving the head of a man, writing the secret
message on his pate with unwashable ink, and then letting
the hair grow back before dispatching him to the
destination. To take an example from modern digital
techniques, one could put the text of a message in the
blank spaces in an image file.

The history of cryptography crackles with famous names.
Shifting the whole alphabet forward or backward by one or
more letters, so that, for example, A becomes B, B becomes
C, and so on, is known as a `Caesar shift', one of the
simplest kinds of cypher or letter-substitution code (see
the title of this article). Julius Caesar also used the ruse of
writing a Latin message in Greek characters so that it would
be unreadable if intercepted by the Gauls. One such missive
was delivered to the besieged Cicero fixed to a spear which
was hurled into his camp by a messenger. And pin-pricking
the letters of an existing document to spell out a secret
message, a form of steganography popular in Victorian
times when newspapers could be sent by post for free,
dates back to Aeneas." Moreover: Tijguz cvtjoftt, The
Economist (London) Aug 28, 1999.
[From Greek stego- (cover) + -graphy (writing).]

Steganography simply takes one piece of information and hides it within
another. Computer files (images, sounds recordings, even disks) contain
unused or insignificant areas of data. Steganography takes advantage of
these areas, replacing them with information (encrypted mail, for
instance). The files can then be exchanged without anyone knowing
what really lies inside of them. An image of the space shuttle landing
might contain a private letter to a friend. A recording of a short sentence
might contain your company's plans for a secret new product.
Steganography can also be used to place a hidden "trademark" in
images, music, and software, a technique referred to as watermarking.

AnnaStrophic ought to be able to describe other methods.

I, for one, have pretty much given up on teaching you where to post weekly theme topics, Dr. Bill, (http://wordsmith.org/board/postlist.pl?Cat=&Board=weeklythemes), but I cannot control the ASp.

s Dr. tBill, e
I greally alike nthe oidea gof
rwhata your ppost hsuggests y.

>s Dr. tBill, eI greally alike nthe oidea gof rwhata your ppost hsuggests y.

and you no doubt have more appreciation for the lengths one must attain to do it efficaciously.

Dear Faldage: I have pretty much given up the idea of teaching you the difference between a day and a week.

the difference between a day and a week

So when I'm using a public restroom I shouldn't use the Men's room because I'm only one man?

Yes, Dr bill, using a standard photocopier to reduce and reduce the size if a printed document won't work, but i remember when i was at xerox, they developed (and never successfully marketed, as per usual) an encrycption code that looked like a "shaded pattern" one of the kind commonly found on " frames" with either WP or Word.. the shaded pattern could hold lots of encryption. so a 50 page document could be encryted onto a single four sided, 1/4 inch "grey" frame. to de encrypt, you would place the document onto another copier, and add a password, otherwise, you'd just get the same grey frame.

now days, encryption is a real science.. often using pairs of prime numbers,

The deal with steganography is that the resulting message doesn't look like it's encoded. YJOD, ;PPLD SMRMV PFRF, RDDSH RSMFO YOD whereas an encoded stenograph wouldn't look like an encoded message.

Dear Faldage:

Why the first comma, please?
And, didn't you leave out ;olr after ;ppld?

The deal with steganography is that the resulting message doesn't look like it's encoded.
Exactly: as Faldage notes, there's a distinction.

For example, if you and I exchange messages using a "Caesar shift" as above [e.g., replace each letter with the letter which follows it int the alphabet], then (as an above post stated), "the files can then be exchanged without any third party knowing what really lies inside of them." However, the snoop would at least know that we were sending some kind of hidden message.

That isn't steganography; its cipher. With steganography, you conceal the fact that any special message exists -- of course you also might, and commonly would, encipher or encode the message. ("Code" is technically not the same thing as cipher, but is also non-steganograhic.)

Example: if you're trying to send a hidden message out of a prison where they censor your mailings, a code/cipher won't do; you need steganograph. A practical means is to send a chatty, innocent message using handwritten script, where your pen would normally "flow" from one letter to the next, not lifting the pen off the page. If you "lift the pen" immediately before selected letters, isconnecting each from the letter preceding, those selected letters can send a steganographic message.

YJOD, ;PPLD SMRMV PFRF, RDDSH RSMFO YOD

I'm sorry, Brain slippage. It should have read:

YJOD, RDDSH R;PPL D;OLR ;PPLD SMRMV PFRF, RDDSH RSMFO YOD

And, didn't you leave out ;olr after ;ppld?


As you can see, yes I did. Good catch, Jackie.

Thanks, Faldage!

Dr Bill, never you mind about the day or the week. 'S'far as I'm concerned, this can be the Daily Theme thread.

I notice that our dear lady wrote
"Dr Bill, never you mind", rather than
"Dr. Bill, never you mind".

No period? Dear woman, are you steganographically telling us of a forthcoming blessed event?

are you steganographically telling us of a forthcoming blessed event?
Awp! At 48?? I don't thi-ink so!
But I wanted to tell you, anyway, that I LOVED your lift-the-pen before certain letters trick! AND--I see that you now have a member.

but not prior to the last post -- so I could only have been responsible for a negative pregnant. But someone must make an honest woman of you, Dear Lady.

but not prior to the last post

Well, Keiva, I guess I'll blush for both of us--however did I come to leave out one rather important word? My post should have read (correction in red):
I see that you now have become a member.!