Which type of cipher rearranges the positions of characters without changing them?

• A. Transposition
• B. Substitution
• C. Code
• D. Hash

Answer: (A)

Rearranging the order of characters without changing the characters themselves is a transposition cipher. In a transposition, every symbol stays the same, but the sequence is permuted according to a rule or key, so the ciphertext looks jumbled even though the letters haven’t been altered. For example, from a plaintext like REVEAL, a transposition could reorder the letters to EVLERA, keeping the same characters but in a different order.

Substitution changes the actual characters themselves by mapping each one to a different symbol, so the content changes, not just the order. Code systems also rely on substitution, using words or tokens to stand in for the original text. A hash produces a fixed-length value from the input and is designed to be one-way and non-reversible, so it isn’t used to rearrange or conceal text in the same way as a cipher.