From the Riddles of Ancient Egypt to Cryptography in the Renaissance — 3500 Years in the Making - Codes: The Guide to Secrecy from Ancient to Modern Times - page 6

colophons are well known with only a couple of numbers for many plaintexts.
In fact, some tablet pieces from this Mesopotamia period have been found in
Susa, in modern-day Iran, consisting of cuneiform numbers in a column next to
cuneiform symbols. Now, in modern-day terminology, if we have a column of
plaintext symbols next to a column of ciphertext numbers, that is an example
of a code-book , since you can look up the code and find the plaintext next to it.
Hence, if this find in Susa is what it purports to be, it is the oldest code book
in the known world. There are not enough of these tablet pieces for the experts
to make a definitive decision on the matter. It makes great fodder for stories
about antiquity, however.
Codes and the Rosetta Stone
We digress here for a moment to discuss the important term “codes”. At
the outset of the chapter, we cavalierly used the term “decode”. However, what
we really meant was “decipher” or “decrypt”, since ciphers are applied to plain-
text independent of their semantic or linguistic meaning. Throughout history
the term “code” has become blurred with that of “cipher” and has come to
mean (in many people's minds) any kind of disguised secret. However, today
the word “code” has a very specific meaning in various contexts. It is usually
reserved for the kind of meaning we have given above when we defined a “code-
book”, a dictionary-like listing of plaintext and corresponding ciphertext. A
cryptographic code means the replacement of linguistic groups (such as groups
of words, or phrases) with numbers, designated words, or phrases, called code-
groups . This is the meaning that we shall use throughout. Moreover, today
there are error-correcting codes , which have nothing to do with secrecy, but
rather refer to the removal of “noise” from, say, a telephone line or satellite
signal; namely, these codes provide a means of fixing portions of a message that
were corrupted during transmission. We will look at such codes in Chapter 11.
The codes with which we are concerned here are the ones defined above, which
are cryptographic codes, since they have to do with secrecy. Now we return to
our historical narrative.
At the beginning of the second century BC, some stonework was created
in Egypt that would prove to be, some 2000 years later, the gateway to an
understanding of virtually all Egyptian hieroglyphs that came before it. It was
discovered in August 1779 by a Frenchman named Bouchard near the town,
known to the Europeans as Rosetta, which is 56 kilometers (35 miles) northeast
of Alexandria. It is called the Rosetta Stone , an irregularly shaped black basalt
stone about 114 centimeters (3 feet 9 inches) long by 72 centimeters (2 feet 4.5
inches) wide, and 28 centimeters (11 inches) thick. It was discovered with three
of its corners broken.
When the French surrendered to the British in Egypt in the spring of 1801, it
came into British possession and now sits in the British Museum. On it are three
different writing systems: Greek letters, hieroglyphics, and demotic script, the
language of the people , which is a cursive form of writing derived from hieratic ,a
simplified form of Egyptian hieroglyphics. Hence, this provided an opportunity