A very different kind of mapping is achieved by performing some sort of permutation on the plaintext letters. This technique is referred to as a transposition cipher.
The simplest such cipher is the rail fence
Rail Fence Technique: Transposition Techniques
Encryption involves writing plaintext letters diagonally over a number of rows, then read off cipher row by row.
For example, the text “meet me after the party” can write (in 2 rows) as:
m e m a t r h p r y
et e f eteo at
Moreover, The ciphertext read from the above row-by-row:
This scheme is very easy to crypt analyze as no key involved.
Transposition cipher can make significantly more secure by performing more than one stage of transposition. The result a more complex permutation that not easily reconstructed.
Difference between Symmetric and Asymmetric key cryptography
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Rotor Machines: Transposition Techniques
- Moreover, The basic principle of the rotor machine illustrated in the figure. The machine consists of a set of independently rotating cylinders through which electrical pulse can flow.
- Each cylinder has 26 input and 26 output pins, with internal wiring that connects each input pin to unique output pin.
- If we associate each input and output pin with a letter of the alphabet, then a single cylinder defines a monoalphabetic substitution.
- If we use multiple cylinders then we will obtain polyalphabetic substitution.