I am studying classical ciphers and have the following doubts:

  1. Is the row and columnar transposition cipher the same?

It is similar since the process of encryption and decryption is the same for both(my opinion).

  1. How did the author get the ciphertext using row transposition cipher? (link: http://williamstallings.com/Extras/Security-Notes/lectures/classical.html)

Key(R): sorcery => 6 3 4 1 2 5 7

Plaintext: laser beams can be modulated to carry more intelligence than radio waves

Ciphertext: erasb lecam snabd umole atoed ctamo ryrre elntl iicee ntgha dnria oesav w


Your second Answer first. [2] write down the key column wise as shown ,then fill the plain text row by row so you will get the matrix of (len(plaintext)/7 x 7), now for ciphertext, take first row and then start taking the value in ascending order of key, see below, key and particular row for ex for row 1:- {1:e, 2:r, 3:a,4:s, 5:b,6:l,7:e} row 2:- {1:c,2:a, 3:m,4:s,5:n, 6:a,7:b} and so on..

so your cipher text would be erasb lecam snab.....

-Key: 6 3 4 1 2 5 7

-PT: l a s e r b e

-PT: a m s c a n b

[1] In columnar transposition cipher you read column wise, for ex. in above example, you can write entire characters of column 1 then 2 ...
so cipher text would be ecdtmecae rauooleds ammernena ....


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