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 8

China
One of those great civilizations, China, did not develop any meaningful cryp-
tography. Perhaps the reason is that most messages were memorized and sent
in person to be delivered orally. Sometimes, if written, usually on rice paper,
the message was concealed by covering it with wax, then either swallowing it,
or concealing it elsewhere on the body. These techniques are examples, not of
cryptography, but rather of steganography , the concealment of the existence of
the message, sometimes called covert secret writing , whereas cryptography is
overt secret writing . (We will study this practice in detail in Section 1.3.) Due
to the ideographic (symbolic writing representing things or ideas) nature of the
Chinese language, ciphers are ruled out as unworkable. Furthermore, since most
of the populace of that time were illiterate, then the mere act of writing would
have been a suGcient form of encryption in itself.
India
The India of antiquity did have numerous forms of cryptographic commu-
nications that, ostensibly, were used in practice. We mention two of the out-
standing contributions from this civilization. One of them is still used today,
namely finger communications (which today would be recognized by hearing-
and speech-challenged people as sign language , or more commonly used today,
signing ). Ancient India called this kind of communication “nirabhasa”, where
joints of fingers represented vowels and the the other parts used for consonants.
The second contribution of Indian civilization of antiquity is that they are re-
sponsible for the first reference in recorded history for the use of cryptanalysis
for political purposes. A classic book on the craft of statehood, written at the
end of the fourth century BC by Kau¸ilya, called the Artha-sastra , contained
suggestions for diplomatic types to use cryptanalysis for obtaining information
necessary to their trade. Although no mechanisms are given for carrying out
such suggestions, there is some cryptographic maturity seated in the knowledge
that such cryptanalysis could indeed be achieved. Later, in Section 1.4, we
will see how the Arabs were the first in recorded history to give a systematic
explanation of cryptanalysis.
The Spartans and Military Cryptography
The first to use military cryptography for correspondence were the Spar-
tans, who used a transposition cipher device. Before describing it, let us have a
look at this new term, “transposition” cipher. First let us clarify and distinguish
it from the earlier use of the term, “substitution” cipher. In the case of a substi-
tution, we replace plaintext symbols with other symbols to produce ciphertext.
As a simple example, the plaintext might be palace , and the ciphertext might be
QZYZXW when a,c,e,l,p are replaced by Z,X,W,Y,Q , respectively. (The cryp-
tographic convention is to use lower-case letters for plaintext and UPPER-CASE
letters for CIPHERTEXT .) However with a transposition cipher, we permute
the places where the plaintext letters sit. What this means is that we do not