Which statement best describes symmetric cryptography?

• A. Uses the same key for encryption and decryption
• B. Requires a public/private key pair
• C. Is primarily used for digital signatures
• D. Is guaranteed to be slower than asymmetric

Answer: (A)

Symmetric cryptography is defined by using the same secret key to both encrypt and decrypt data. Because both parties share this single key, it can be used for fast, efficient encryption of large amounts of data, which is why symmetric algorithms like AES are commonly used for bulk protection. The catch is securely sharing and managing that key between sender and receiver.

The other statements describe characteristics of different approaches or incorrect claims: requiring a public/private key pair is a hallmark of asymmetric (public-key) cryptography, not symmetric. Digital signatures are typically produced with asymmetric methods, which use a private key to sign and a public key to verify. The claim that symmetric cryptography is guaranteed to be slower than asymmetric is false; in practice, symmetric approaches are usually much faster.