Cryptography Reference
In-Depth Information
prominent British poet before Shakespeare. In the 1390s he wrote his best-
known work, the unfinished Canterbury Tales . Our interest, however, comes
from a work written in 1392, namely, The Equatorie of the Planetis , which
was a supplement to his 1391 Treatise on the Astrolabe . In the Equatorie ,he
included six passages written in cipher. The cryptosystem that he used consisted
of a substitution alphabet of symbols, where for instance, the letter h might be
represented by a symbol looking like the Greek letter σ , sigma . He also talks of
a cipher “using magic figures and spells.” This brings us to the association that
cryptography has had with the occult and black magic.
Codes and the Occult
One of the best-known enciphered magic writings is the Leiden papyrus ,
which was actually written in the third century BC. It has both Greek and
demotic symbols as enciphering techniques to hide the “magic recipes”, among
which are spells for making potions that would give a man an incurable skin
disease, and another on how to make a woman desire a man. Of course, none
of these work. However, it is a precursor to the kinds of “magical” associations
that cryptography had in the Middle Ages.
Part of the reason for the lingering air of the occult attached to cryptog-
raphy today is due to the association with secret spells and incantations, the
history of which we will discuss. It was assumed, in the Middle Ages, that these
incantations bestowed power on the sorcerer who voiced them, and that the
removal of a disguise from a secret is somehow miraculous or magical. However,
the extraction of information by modern cryptographic techniques has become
an objective science, whereas the unfortunate association with divination, or
insight into the future, is subjective and at best an amusing distraction in our
modern world. Through education about cryptology, we can remove this aura
of the occult and better understand it as a science with a fascinating history.
Now let us learn more about why such an aura lingers.
In the late Middle Ages, February 2, 1462, Johannes Trithemius was born in
Trittenheim, Germany. In 1482, subsequent to attending school in Heidelberg,
he entered the Benedictine monastery of Saint Martin in Sponheim, Germany.
In a very short time he was designated abbot, probably due to the recognition
of his clear and outstanding brilliance. He became a prolific writer, known
for his biographical dictionaries, and an encyclopedic bibliography, Liber de
scriptoribus ecclesiasticus , published in 1494, which earned him the title of the
Father of Bibliographies . This has become a reference work on church writers
that is used to this day. However, Trithemius had interests on the darker side.
Trithemius authored topics on alchemy, witchcraft, planetary angels, and
general topics of the occult. In particular, in his book Steganographia ,
Trithemius describes techniques that we today call aspects of steganography , the
etymology of which is from the Greek steganos meaning impregnable , and from
a secrecy point of view, this means concealing the very existence of the message
itself, rather than the cryptographic goal of disguising the message. We have
actually encountered various uses of steganography in earlier sections (pages 8
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