Which concept allows performing computations on ciphertexts that translate to the same computations on the plaintext?

• A. Hashing
• B. Symmetric key exchange
• C. Homomorphic encryption
• D. Digital signatures

Answer: (C)

The idea is homomorphic encryption. It allows you to perform computations directly on encrypted data, and when you decrypt the result you obtain the same outcome as if you had performed those computations on the plaintext. This means additions, multiplications, or other supported operations on ciphertexts map to the corresponding operations on the underlying data, enabling secure processing without exposing the plaintext. Hashing is one-way and does not support reversible calculations on ciphertext to recover or compute plaintext results. Symmetric key exchange is about sharing keys securely for encryption and decryption, not about enabling computations on encrypted data. Digital signatures provide authentication and integrity, not the ability to compute on ciphertext to yield plaintext results.