Simple Square Cipher
A pen and paper puzzle for simple messages which is quick and easy but not secure. It is for use among Muggles and is good for brief and temporary messages.
Five Square Starter
The Magic Square wherein numbers sum to the same figure in rows and columns - and even diagonally - has been a curiosity for centuries. Heinrich Cornelius Agrippa von Nettesheim provided this Square of Mars that sums to 5 x 13 in all directions using the numbers 1 to 25. He served as a secretary to the Holy Roman Emperor Karl V.
Put letters into the square in the sequence 1 to 25 and you have a cipher jumble:
EESUP HTSEI NESAC RSCER RRQIS
This is not really easy or practical. There are other arrangements of 25 letters in a 5 x 5 square. Have a look at this SIMPLE NOTE.
https://simplebooklet.com/sumsandshapes
The Square of Mars
CIPHER SECRETS SET IN SQUARES
Codes and Ciphers is about communication: sure, we do puzzles and secrets as well …