Rules for Substitution
Cryptograms
In the simple substitution cryptogram, the
coded message is formed by substituting one letter (or other symbol) for
another letter in the uncoded message (called "clear text" or "plaintext"),
each and every time the letter occurs in the plaintext. Thus, if you chose
to let "P" in the plaintext be represented by "X" in the coded text, "O"
by "M," "S" by "G," and "T" by "W," the plaintext word "POST" would be
coded "XMGW," plaintext "STOP" would be coded "GWMX," and plaintext "SPOT"
would be coded "GXMW."
Although, in its most basic form, the simple
substitution cipher is comparatively easy to break, the use of nulls and
frequently changed patterning schemes, as well as keywords and odd word
division patterns, can render the simple substitution cipher more difficult
to break. As Q notes in The
Quiller Memorandum, "All ciphers are broken by applying three tools:
mathematics, the laws of frequency, and trial-and-error. The most experienced
cryptographer uses these three tools and plies them with patience, the
prime mover."
For an excellent introduction to the breaking
of simple substitution ciphers, check out this fantastic lecture
by "LANAKI" posted by the American Cryptography Association (another great
bunch of folks to go
and join).
The three messages on the substitution
cipher page are simple substitutions. In an effort to "raise the bar"
in the face of increased skill among the "Elites," none of the substitution
cryptograms have normal word divisions.
Neglect not the "crib"!
In addition to notes about level of difficulty and "enhancements" (variations
on the basic simple substitution cipher), you are given a clue. The clue
is for the purpose of giving you what is known to cryptanalysts as a "crib,"
a way of getting a likely word you expect to find in a plaintext and then
using that word to pry out a few letters of the coded text.
***Take
me to the simple substitution cryptograms!***
