Transposition ciphers rearrange symbols in a plaintext message to produce ciphertext without disguising the symbols. They aim to widely spread information from the message across the ciphertext to break patterns. Three types of transposition ciphers are described: route ciphers reorder symbols along different routes; rail fence ciphers layer plaintext in diagonal lines like a rail fence; and columnar transposition ciphers write plaintext in rows and read ciphertext out by columns ordered by a keyword-generated key. An example of columnar transposition is provided.

1. Transposition
Chiper(Grid)

2. Transposition Ciphers
Transposition cipher – reorders (rearrange) symbols but does not disguise
them. It is also called permutation
With transposition, the cryptography aims for diffusion
◦ Widely spreading the information from the message or the key across the ciphertext
◦ Transpositions try to break established patterns
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3. Transposition Ciphers
1. Route Cipher 3

4. Transposition Ciphers
2. Rail Fence Cipher 4

5. Transposition Ciphers
3. Columnar Transposition
Plaintext written in rows
Number of columns = key length
Key is used to number the columns
Ciphertext reads out by columns, starting with column whose key letter is
lowest
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6. Transposition Ciphers
3. Columnar Transposition
For example:
◦ Assume we used ZEBRAS as keyword
◦ Plaintext (M): WE ARE DISCOVERED FLEE AT
ONCE
◦ Key (K): 6 3 2 4 1 5
◦ Ciphertext(C): EVLNE ACDTK ESEAQ ROFOJ DEECU
WIREE
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7. Example: Columnar cipher
Ciphertext(C): EVLNX ACDTX ESEAX ROFOX DEECX
WIREE
Key: 632415
Plaintext (M): WE ARE DISCOVERED FLEE AT ONCE