Double Transposition Ciphers
Double transposition ciphers are very similar to normal transposition ciphers but
are more complex in their design and are harder to decipher. There are also multiple
methods for creating a double transposition cipher. One example is shown below:
Start with a keyword such as "shoes." Create a matrix grid below the keyword and
write in your secret message from left to right. Then assign an order of sequencing
to the columns or rows in your matrix. In the example below the cipher is made more
difficult by ordering the columns out of order. The letter "Z" is used to fill in blank
spaces found inside of the matrix. Each column or row, in numbered order, is then
written down in blocks of 3 to 5 letters, in all uppercase, to encipher the message.
Plain Message: Pay me by Sunday or suffer the consequences.
Enciphered Message: PGDSR OUSEN RECQE ZAYAU TNEZM UOFEE CZYSY FHSNZ
To decipher the message you need to know how many letters are in the keyword and what
order to arrange the columns for rewriting the enciphered letters into the matrix.
To make it even harder you may want to try other patterns of enciphering your message
with a keyword. Try spiraling outwards from the middle letter in your matrix, go
right to left from the bottom corner to the upper left corner, or zig zag up and
down through different columns or rows.
*Can you figure out why the enciphered message is in all uppercase? What does uppercase
hide from your enemy? What would case sensitive text give away?