Math for Liberal Studies: Decoding a Message Using the Bifid Cipher

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in this video we'll be learning to

decode a message using the bifid cipher

here's a typical problem decode the

message GH p k FN hygiene using the

bifid cipher with the keyword eagles

here's how this will work the first step

will be to make what's called the

Polybius where the Polybius square is a

5 by 5 grid it's got five rows running

horizontally and five columns running

vertically each of the rows and columns

are numbered 1 through 5 and what this

does is it lets us describe each of the

locations in the grid by true numbers

the row number and the column number so

in this grid we'll be filling in the

letters of our alphabet we want to make

sure that we never repeat any letters

and so every letter should appear here

exactly once but since there's only 25

positions and 26 letters in our alphabet