Our students enjoyed trying to solve a simple substitution cipher using frequency tables.
The following message was encoded using a simple substitution cipher and is included for your students to decode:
Simple substitution ciphers like these are easy to solve, even if the code is not known, as shall be shown subsequently.
About 2,000 years ago, transposition ciphers had made the barest appearance and Julius Caesar carried on correspondence in a very simple substitution cipher
Criminals typically use homemade, simple substitution cipher systems which use a single cipher text character to replace a plain text character.
Using these and many other known language characteristics, a cryptanalyst can often decipher a simple substitution cipher with little difficulty.
Cryptanalysis of the Playfair cipher is much more difficult than normal simple substitution ciphers
, because digraphs (pairs of letters) are being substituted instead of monographs (single letters) .
Experiments with relaxation algorithms for breaking simple substitution ciphers