Implementing a Stream Cipher for Enhanced Security

C.

The correct answer to this question is option C: Symmetric algorithm.

A stream cipher is a type of encryption algorithm that encrypts data one bit or byte at a time. It uses a key and a pseudorandom number generator to generate a stream of cipher bits that are XOR'd with the plaintext to produce the ciphertext. Stream ciphers are typically faster than block ciphers because they do not require padding or block alignment.

A hash function is a one-way mathematical function that generates a fixed-length output from an input. Hash functions are used for data integrity and authentication purposes, but they are not used for encryption.

Elliptic curve cryptography is a public-key cryptography technique that uses the mathematics of elliptic curves to provide encryption and digital signature capabilities. It is used primarily for key exchange and digital signatures, but it is not used for stream ciphers.

Public key cryptography, also known as asymmetric cryptography, uses a pair of keys to encrypt and decrypt data. The two keys are mathematically related, but one key is kept secret (private key) while the other is publicly known (public key). Public key cryptography is not typically used for stream ciphers.

Symmetric algorithms, also known as secret key cryptography, use the same key for both encryption and decryption. This means that the key must be kept secret to maintain security. Symmetric algorithms are well-suited for stream ciphers, as they can efficiently encrypt data one bit or byte at a time.

In summary, a stream cipher requires a symmetric algorithm to function. Therefore, the correct answer to the question is option C: Symmetric algorithm.