Multialphabet substitution is a type of which cipher family?

• A. Substitution
• B. Transposition
• C. Hashing
• D. Stream cipher

Answer: (A)

Substitution ciphers replace each plaintext symbol with a corresponding ciphertext symbol according to a mapping. Multialphabet substitution extends this idea by using several different mappings (alphabets) for different positions or keys, but the core operation is still replacing symbols, not rearranging them. Transposition would shuffle the order of characters, hashing creates a one-way digest, and a stream cipher combines plaintext with a keystream rather than simply substituting symbols. So multialphabet substitution belongs to the substitution cipher family.