On the Subject of the Square CM

A machine that knows no bounds when it comes to ciphers.

From the Shape Cipher module by TracksJosh.

Create a key using the keyword on screen 1 and the Boolean Expression on screen A. Make sure to replace any Js with Is. Rearrange the key into a 5×5 matrix.

For each letter of the encrypted word, do the following:

• Find the Nth letter of the encrypted word in the matrix.
• Find the Nth letter shown on screen 2 in the matrix.
• Create a 4 sided shape using the 2 letters found in the matrix as the corners.
• Take the sum of the alphabetic positions (A1Y25Z0) of the letters within this 4 sided shape.
• Modulo the result by 26 and turn it back to a letter (A1Y25Z0) to get your Nth decrypted letter.

Note: The sum of the entire matrix is equal to 341 or 3.

Example 1

Encrypted Word: MYCN
Screen 2: SGBW

B	C	E	F	G
H	I	K	L	M
N	O	P	Q	S
T	U	V	X	Y
Z	D	R	A	W

MS → M + S → 32 MOD 26 → 6 → F
YG → G + M + S + Y → 64 MOD 26 → 12 → L
CB → B + C → 5 MOD 26 → 5 → E
NW → N + O + P + Q + S + T + U + V + X + Y + Z + D + R + A + W → 239 MOD 26 → 5 → E
Decrypted Word: FLEE