Which statement correctly contrasts symmetric and asymmetric cryptography?

• A. Symmetric provides digital signatures only; Asymmetric provides encryption
• B. Symmetric uses a single shared key for encryption and decryption; Asymmetric uses a key pair for encryption/decryption and digital signatures
• C. Symmetric uses key pairs; Asymmetric uses a single key
• D. Symmetric cannot be used for encryption; Asymmetric is only for signing

Answer: (B)

Key distinction is how the keys are used to protect data. Symmetric cryptography relies on one shared secret key to both encrypt and decrypt information. Everyone who needs access must have that same key, which makes the process fast for large amounts of data but requires secure key exchange and protection of the key itself.

Asymmetric cryptography uses a pair of keys: a public key that can be shared openly for encryption or verification, and a private key that stays secret for decryption or signing. This setup not only enables encryption without distributing a secret key but also enables digital signatures, where a message signed with the private key can be verified with the corresponding public key.

So the statement that symmetric uses a single shared key for encryption and decryption, while asymmetric uses a key pair for encryption/decryption and digital signatures, is the correct description. The other options mix up how the keys are used and the capabilities of each type.