01 What is the Mexican Army Cipher Wheel?

The Mexican Army Cipher Wheel. With the Mexican Army Cipher Wheel, we… | by Prof Bill Buchanan OBE FRSE | ASecuritySite: When Bob Met Alice | Medium

The Mexican Army Cipher Wheel is a polyalphabetic monographic substitution cipher.

The wheel consists of five discs, the position of which can be freely adjusted.

From the outside to the inside:

  • Letters A – Z
  • numbers 01 – 26
  • numbers 27 – 52
  • Numbers 53 – 78
  • Numbers 79 – 100

The key is defined by

  • four numbers that lie below the A
  • four letters for the numbers 01, 27, 53 and 79.

Then the letters are encrypted by the respective numbers or the four numbers are decrypted to the letters.