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.
123456
1ABCDEF
2GHIJKL
3MNOPQR
4STUVWX
5YZ0123
6456789

Example

Encrypted Word: GARSF
Page 1 Screen 1: BEGHKMNO
Page 1 Screen 2: ACDGHKM
Page 1 Screen 3: BEHIK
Page 1 Screen 4: BCFGI
Page 2 Screen 1: ADFG
Page 2 Screen 2: ACD
Page 2 Screen 3: FGJCFD
Pages 1-2 Screens A-D: JR7DHP5XJ5RIZXT

0100101100101110
1011001100101
01001001101
011001101
1001011
10110

Shifting the rows: FGJCFD

0110010111001001
1100101101100
01010010011
100110101
1110010
10101

JR7DHP5XJ5RIZXT → 426364142234266442626332254624

1:0110010111001001
9:1100101101100
4:01010010011
8:100110101
1:1110010
7:10101

G → 27 - 7 → 20 + 9 + 8 + 1 + 7 → 45 - 26 → 19 → S

1:1100101110010010
9:1001011011001
4:10100100110
8:001101011
1:1100101
7:01011

A → 27 - 1 → 26 + 1 + 9 + 4 + 1 → 41 - 26 → 15 → O

1:1001011100100101
9:0010110110011
4:01001001101
8:011010110
1:1001011
7:10110

R → 27 - 18 → 9 + 1 + 1 + 7 → 18 → R

1:0010111001001011
9:0101101100110
4:10010011010
8:110101100
1:0010111
7:01101

S → 27 - 19 → 8 + 4 + 8 → 20 → T

1:0101110010010110
9:1011011001100
4:00100110101
8:101011001
1:0101110
7:11010

F → 27 - 6 → 21 + 9 + 8 + 7 → 45 - 26 → 19 → S

Decrypted Word: SORTS