Condi
History
First published in the Sep-Oct 2011 edition of American Cryptogram Association (ACA) magazine The Cryptogram the Condi cipher is so named because it uses CONsecutive DIgraphs and developed by ACA member G4EGG. It tries to hide pattern words and disguise frequency counts.
Description
The Condi cipher uses the position of the preceding plaintext letter in a keyed alphabet to generate the next ciphertext letter. A keyed alphabet is created from a keyword, with repeated letters being omitted, followed by the unused letters of the alphabet in alphabetical order. The position of each letter in the keyed alphabet is then labelled to help with the enciphering.
For example the keyword HAPPINESS is reduced to HAPINES when repeated letters are removed. Appending unused alphabet letters produces the following keyed alphabet:
HAPINESBCDFGJKLMOQRTUVWXYZ
These are then numbered consecutively as follows:
.........11111111112222222
12345678901234567890123456
HAPINESBCDFGJKLMOQRTUVWXYZ
An initial number is chosen, between 1 and 25, say 7. This is the starting offset for the enciphering.
Locate the first plaintext letter in the keyed alphabet and count 7 characters further along the alphabet, wrapping back to the beginning if necessary. This character is the first ciphertext letter. The position of this ciphertext letter, say 13, is the new offset for the next plaintext letter. Locate the second plaintext letter in the keyed alphabet, and locate the letter 13 positions along and this becomes the second ciphertext letter. Keep repeating this until the whole plaintext has been enciphered.
Example
Keyword: HAPPINESS
Starting number: 7
Plaintext: Real happiness is when you marry a girl for love and find out later she has money.
Plaintext: Real happiness is when you marry a girl for love and find out later she has money
Ciphertext: ZYBO MPNESCFJK FF IXSF IMG FQUGQ H KMWB ZAD BEJA BSL ULCL HGL COVZY ZBS SPC WSVFN
Solving
Solving methods: Hill Climbing and Dictionary keyword search.
The Condi cipher type enables a tip to be included when solving with a dictionary search. This is optional but including a tip improves the solving speed.
On selecting the Solve button using a dictionary search a dialog box will appear to enable the tip and tip location to be set. On selecting OK the program will search for a solution.
Tip – Enter the tip in the Tip field including spaces between words.
Click on the Locate tip button will populate the Tip location list with possible locations for the tip.
Tip location – Select the location of the tip from the list then press OK. When a tip location is selected the ciphertext and plaintext positions are shown below the Tip location.
