On the Subject of the Chaocipher 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. This will be referred to as Key A.

Create a key using the keyword on screen 2 and the Boolean Expression on screen B. This will be referred to as Key B.

Write Key A above Key B and place an asterisk above the 14th letter of the keys.

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

Encrypt Instructions

• Find the Nth letter of the encrypted word in Key A. This will be called Character A.
• Replace it with the letter in Key B. This will be called Character B.
• Shift Key A so that the last letter of the key is Character A. Take out the 3rd letter of Key A and place it back in at the position of the asterisk.
• Shift Key B so that the 1st letter of the key is Character B. Take out the 2nd letter of Key B and place it back in at the position of the asterisk.

Decrypt Instructions

• Find the Nth letter of the encrypted word in Key B. This will be called Character B.
• Replace it with the letter in Key A. This will be called Character A.
• Shift Key A so that the last letter of the key is Character A. Take out the 3rd letter of Key A and place it back in at the position of the asterisk.
• Shift Key B so that the 1st letter of the key is Character B. Take out the 2nd letter of Key B and place it back in at the position of the asterisk.

Do this for each letter of the encrypted word to get a decrypted word.

Example 1

Encrypted Word: MFBGY
Key A: BARGINCDEFHJKLMOPQSTUVWXYZ
Key B: BCFGHJKLOPQRSUVWXYZDEMNTIA
Using Encrypt Rules

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B

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M → V

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F → O

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B → I

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Y → E

Decrypted Word: VOICE

Example 2

Encrypted Word: SZFZZ
Key A: ABCDEFGHJKMNOPQSUVWXYZTRIL
Key B: GUESTABCDFHIJKLMNOPQRVWXYZ
Using Decrypt Rules

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S → D

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Z → A

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Z → C

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Decrypted Word: DANCE