Editing Transposition cipher (section)

=== Encryption ===

In a columnar transposition, the message is written out in rows of a fixed length, and then read out again column by column, and the columns are chosen in some scrambled order. Both the width of the rows and the permutation of the columns are usually defined by a keyword. For example, the keyword {{mono|ZEBRAS}} is of length 6 (so the rows are of length 6), and the permutation is defined by the alphabetical order of the letters in the keyword. In this case, the order would be "6 3 2 4 1 5".

In a regular columnar transposition cipher, any spare spaces are filled with nulls; in an irregular columnar transposition cipher, the spaces are left blank. Finally, the message is read off in columns, in the order specified by the keyword. For example, suppose we use the keyword {{mono|ZEBRAS}} and the message {{mono|WE ARE DISCOVERED. FLEE AT ONCE}}. In a regular columnar transposition, we write this into the grid as follows:
 6 3 2 4 1 5
 W E A R E D
 I S C O V E 
 R E D F L E 
 E A T O N C 
 E Q K J E U 
providing five nulls ({{mono|QKJEU}}), these letters can be randomly selected as they just fill out the incomplete columns and are not part of the message. The ciphertext is then read off as:
 EVLNE ACDTK ESEAQ ROFOJ DEECU WIREE

In the irregular case, the columns are not completed by nulls:
 6 3 2 4 1 5
 W E A R E D 
 I S C O V E 
 R E D F L E 
 E A T O N C 
 E 
This results in the following ciphertext:
 EVLNA CDTES EAROF ODEEC WIREE