Concepts in Data Encryption:
Double transposition ciphers are very similar to normal transposition ciphers but are more
complex in their design and are harder to decipher. Observe the diagram below and note how
they differ only slightly. There are also multiple methods for creating a double
transposition cipher. One example is shown below:
Start with a keyword such as "encrypt." A matrix grid is created below the
keyword and the secret message is written in from left to right. An order of sequencing to
the columns or rows in then assigned into the matrix grid. In the example below the cipher
is made more difficult by ordering the columns out of order, that is, unlike transposition
method illustrated above, it does not follow the alphabetic 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: 'Welcome to the exciting world of encryption'.
Enciphered Message: OENOPZ EOIRCN LTTLRZ WTCONO CHIDYZ MEGFTX EXWEIZ
Why is the enciphered message in all uppercase? If one is observant enough, it is
apparent that a case sensitive text would at least give away the number of words that are
contained in the message, not mentioning much more steps which become unnecessary as one
tries to decipher it.