The Decimation Cipher

message

cipher

encryption value

3

encrypt

decrypt

next step

new example

c

i

p

h

e

r

The decimation cipher encrypts a message by using modular arithmetic. Each letter in the message is replaced by its position in the alphabet (a → 0, b → 1, …, z → 25). These position values are then multiplied by an encryption value. Multiplication is done modulo 26, and the resulting products are replaced by their corresponding letters to arrive at the encrypted message.