﻿ Double Square Rotation CM — Keep Talking and Nobody Explodes Module

## On the Subject of the Double Square Rotation CM

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

From the Synapse Cipher module by Kilo Bites and VFlyer.

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 Square A.

Create a 2nd matrix by doing the same steps to create Square A but with the keyword on screen 2 and the Boolean Expression on screen B. This will be called Square B.

Obtain the alphabetic positions of each letter in the keyword on screen 3 (A1Z26) and modulo this by 10. This will be Offset Key.

If the Submit Button is white, follow the instructions under Encrypt Instructions. Otherwise, follow the instructions under Decrypt Instructions.

#### Encrypt Instructions

• Start from Square A and alternating between Square B.
• Find the Xth letter in the provided square.
• If the letter obtained is at the center of the square, do not modify that letter. Otherwise, count Y times counterclockwise around the given region from where the letter is at, Y being the Xth number from the Offset Key for this step.

#### Decrypt Instructions

• Start from Square A and alternating between Square B.
• Find the Xth letter in the provided square.
• If the letter obtained is at the center of the square, do not modify that letter. Otherwise, count Y times clockwise around the given region from where the letter is at, Y being the Xth number from the Offset Key for this step.

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.

All counts must stay within the same region as the letter that was started on. Do not change regions when counting! I.E. From the diagram, do not go from the green region to blue or blue to red, and vice versa.

#### Example 1

Encrypted Word: DERBRK

Screen 3: TEDIUM

Constructed Squares:

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

Alphabetic positions of each letter in screen 3's keyword, mod 10: 0, 5, 4, 9, 1, 3

Using Encrypt Rules

D, CCW 0 -> D

E, CCW 5 -> I

R, CCW 4 -> N

B, CCW 9 -> N

R, CCW 1 -> E

K, CCW 3 -> R

Decrypted word: DINNER

#### Example 2

Encrypted Word: ZRGEFW

Screen 3: GLOOMY

Constructed Squares:

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

Alphabetic positions of each letter in screen 3's keyword, mod 10: 7, 2, 5, 5, 3, 5

Using Decrypt Rules

Z, CW 7 -> C

R, CW 2 -> I

G, CW 5 -> V

E, CW 5 -> I

F, CW 3 -> C

W, CW 5 -> S

Decrypted word: CIVICS