On the Subject of the Trisquare CM

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

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. This will be called Matrix A.

Create a 2nd and 3rd matrix by doing the same steps to create Matrix A but with the keyword on screen 2 and the Boolean Expression on screen B to create Matrix B and the keyword on screen 3 and the Boolean Expression on screen C to create Matrix C.

Form an backwards L shape pattern with Matrix C being in the bottom right, Matrix A in the bottom left, and Matrix B in the top right.

Concatenate the encrypted word and the letters displayed on screen D in that order. Then split the string into groups of 3 letters, unless the length of the string is not divisble by 3, then the last group will contain 2 letters.

For each 3 letter group, do the following:

• Find the 1st letter of the Nth letter group in Matrix A.
• Find the 2nd letter of the Nth letter group in Matrix B.
• Find the 3rd letter of the Nth letter group in Matrix C.
• Use the intersection of the column in Matrix A and the row in Matrix C to get the 1st letter of the Nth decrypted pair.
• Use the intersection of the row in Matrix B and the column in Matrix C to get the 2nd letter of the Nth decrypted pair.

For the 2 letter group, do the following:

• Find the 1st letter of the Nth letter group in Matrix A.
• Find the 2nd letter of the Nth letter group in Matrix B.
• Use the intersection of the row in Matrix A and the column in Matrix B to get the Nth decrypted letter from Matrix C.

Finally, if any of the letters on screen 4 match at the same position as any of the letters of your encrypted word, replace that letter with a J. You should now have an decrypted word.

Example

Encrypted Word: KIBRS
Screen 4: ALKWA
Matrix A: CRAWLINGBDEFHKMOPQSTUVXYZ
Matrix B: BCDEFGHKLMNOPQRUVXYZWAIST
Matrix C: MEDICABFGHKLNOPQRSTUVWXYZ
Screen D: AME

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

KIB → BA
RSA → NW
ME → O
BANWO + ALKWA → BANJO
Decrypted Word: BANJO