Which statement correctly contrasts symmetric and asymmetric encryption, and which algorithms exemplify each?

• A. Asymmetric encryption uses the same key for encryption and decryption; AES is an example.
• B. Symmetric encryption uses the same key for encryption and decryption; AES is an example.
• C. Asymmetric encryption uses public/private keys; RSA is an example.
• D. Symmetric encryption uses public/private keys; ECC is an example.

Answer: (B)

The key idea is how keys are used to encrypt and decrypt. Symmetric encryption relies on a single shared key for both operations. AES is a prime example of this: the same secret key is used to encrypt data and to decrypt it back to its original form. This makes symmetric schemes typically very fast and suitable for protecting large amounts of data, but it also means the key must be securely shared between parties before communication.

In contrast, asymmetric encryption uses a pair of keys—a public key for encryption and a private key for decryption—which supports secure key exchange and digital signatures. RSA is a well-known example of an asymmetric algorithm, and ECC is another widely used asymmetric approach based on elliptic curves.

So the statement that symmetric encryption uses the same key for encryption and decryption with AES as an example correctly contrasts the two types. The other options misstate how the keys are used or mislabel the algorithms (for instance, describing AES as asymmetric or claiming symmetric uses public/private keys).