We return to the series on columnar transposition ciphers to discuss permutations, how CTCs can be thought of as permutations, and some questions that this connection opens up.

Today’s Math Monday begins a multi-part series on the columnar transposition cipher. Today’s Math Monday begins a multi-part series on the columnar transposition cipher. Skip to content.

Crack the Ciphers by Jim Gillogly Here ... Double Playfair, and Double Transposition ciphers, respectively. In the opening paragraph for each challenge, we link to instructions ...

To decrypt a double transposition, construct a block with the right number of rows under the keyword, blocking off the short columns. Write the cipher in by columns, and read it out by rows.