Editing Transposition cipher (section)

=== Decryption ===

To decipher it, the recipient has to work out the shape of the enciphering grid by dividing the message length by the key length to find the number of rows in the grid. The length of the grid's last line is given by the remainder. The key is written above the grid, and the ciphertext is written down the columns of the grid in the order given by the letters of the key. The plaintext appears on the rows. A partial decipherment of the above ciphertext, after writing in the first column:

 6 3 2 4 1 5
 . . . . E .
 . . . . V .
 . . . . L .
 . . . . N .
 .

In a variation, the message is blocked into segments that are the key length long and to each segment the same permutation (given by the key) is applied. This is equivalent to a columnar transposition where the read-out is by rows instead of columns.