Which is a type of homomorphic encryption?

• A. AES
• B. RSA
• C. Full homomorphic encryption (FHE)
• D. SHA-256

Answer: (C)

Homomorphic encryption lets you perform operations on ciphertexts that translate into the same operations on the underlying plaintext when you decrypt. Full homomorphic encryption is the type that supports arbitrary computation on encrypted data, meaning you can evaluate any function or circuit without ever decrypting, and get the correct result when you do decrypt. That makes it a genuine type of homomorphic encryption.

The other options don’t fit this idea. AES is a symmetric encryption algorithm, not designed for computing on ciphertexts to yield meaningful plaintext results. SHA-256 is a hash function, not encryption, so it doesn’t provide a reversible mapping or allow computations on ciphertexts to reflect plaintext operations. RSA is a public-key encryption scheme with some algebraic properties (notably multiplicative), but it’s not categorized as a fully homomorphic encryption system designed for arbitrary computation on encrypted data.