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!***