## On the Subject of the M-209 CM

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

**This cipher uses 2 pages.**

Create an M-209 machine by following the instructions below:

**1:**Write down 16 zeros for row 1, 13 zeros for row 2, 11 zeros for row 3, 9 zeros for row 4, 7 zeros for row 5, and 5 zeros for row 6.**2:**For each letter on page 1 screen 1, replace the zero with a one with at row 1, at the column equal to the alphabetic position of the letter (A1Z26).**3:**Repeat step 2 for row 2 using the letters on page 1 screen 2.**4:**Repeat step 2 for row 3 using the letters on page 1 screen 3.**5:**Repeat step 2 for row 4 using the letters on page 1 screen 4.**6:**Repeat step 2 for row 5 using the letters on page 2 screen 1.**7:**Repeat step 2 for row 6 using the letters on page 2 screen 2.**8:**For each letter on page 2 screen 3, shift the Nth row to the left, equal to the alphabetic position of the Nth letter, minus 1 (A0Z25).**9:**Turn each character on pages 1 and 2, screens A–D into a row/col pair using the table below.**10:**For each row, the offset for the Nth row is equal to the number of N numbers you got from the previous step.

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

- Subtract 27 by the alphabetic position of the Nth letter of the encrypted word (A1Z26).
- For each row of the M-209 machine, if the left most digit is a 1, add the offset of that row to the number.
- If the number is greater than 26, subtract 26 until it is between 1–26.
- Convert the number back to a letter to get your Nth decrypted letter (A1Z26).
- Shift all the rows of the M-209 machine to the left one.

1 | 2 | 3 | 4 | 5 | 6 | |
---|---|---|---|---|---|---|

1 | A | B | C | D | E | F |

2 | G | H | I | J | K | L |

3 | M | N | O | P | Q | R |

4 | S | T | U | V | W | X |

5 | Y | Z | 0 | 1 | 2 | 3 |

6 | 4 | 5 | 6 | 7 | 8 | 9 |