There are two rings, inner and outer, each with all 26 letters, and you can move the rings relative to one another.Ī simple substitution cypher would be to just set the decoder ring and encypher your message. Imagine you have a simple decoder ring like you would stereotypically get from a cereal box. So our key of CORGICORGIC shifts the plaintext of REDDITRULES to our ciphertext TSUJQVFLRMU. Now we loop back and start the keyword again. In the I shift (moving 8 letters), I becomes Q. In the G shift (moving 6 letters), D becomes J. In the R shift (moving 17 letters), D becomes U. In the O shift (moving 14 letters), E becomes S. In the C shift (moving two letters), R becomes T. We take out message, say REDDITRULES, and we encrypt it by using a different Caesar shift for each letter, according to the codeword.
#Polyalphabetic cipher code#
Now we need a code word, let's say CORGI. We can identify these different shifts by what the letter A becomes. Or you could shift two spaces, A to C, B to D, C to E., Y to A, Z to B. So A becomes B, B becomes C, C becomes D, etc, and Z becomes A.
A Caesar cipher (or a shift cipher, or a Caesar shift) is when you take the whole alphabet and shift it along some number of spaces. One simple way to do this is with a bunch of Caesar ciphers.