 ## On the Subject of the Sean CM

Create a key using the keyword on screen 1 and the Boolean Expression on Screen A. Split the key in half and place the 2nd half underneath the 1st half. This will be referred to as "THE SEAN SHIFTER".

If the Boolean Expression on screen 2 is true, follow the instructions under Instruction Set A. Otherwise follow the instructions under Instruction Set B.

#### Instruction Set A

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

• Find the Nth letter of the encrypted word in THE SEAN SHIFTER and replace it with the letter above/below.
• Take the last letter of the top half of THE SEAN SHIFTER and place it at the front of the top half.
• Swap the first letter of the top half with the first letter of the bottom half of THE SEAN SHIFTER.
• Take the first letter of the bottom half of THE SEAN SHIFTER and place it at the back of the bottom half.

#### Instruction Set B

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

• Find the Nth letter of the encrypted word in THE SEAN SHIFTER and replace it with the letter above/below.
• Take the last letter of the bottom half of THE SEAN SHIFTER and place it at the front of the bottom half.
• Swap the first letter of the top half with the first letter of the bottom half of THE SEAN SHIFTER.
• Take the first letter of the top half of THE SEAN SHIFTER and place it at the back of the top half.

The resulting letters should form a decrypted word.

#### Example 1

Encrypted Word: YQWNDQ
Sean Shifter: CONTRASBDEFGHIJKLMPQUVWXYZ
Using Instruction Set A

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

Y → G

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

Q → R

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

W → A

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

N → V

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

D → E

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

Q → L

Decrypted Word: GRAVEL

#### Example 2

Sean Shifter: NEATHBCDFGIJKLMOPQRSUVWXYZ
Using Instruction Set B

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

M → E

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

E → N

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

A → E

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

D → M

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

S → Y

Decrypted Word: ENEMY