Which statement best describes symmetric encryption?

• A. It uses the same key for encryption and decryption
• B. It uses different keys for encryption and decryption
• C. It is only used for hashing
• D. It cannot be used for public-key systems

Answer: (A)

Symmetric encryption uses the same secret key for both encryption and decryption. Because the same key does both tasks, keeping that key private and sharing it securely between sender and receiver is essential. This contrasts with asymmetric encryption, which relies on a public key for encryption and a separate private key for decryption. Symmetric methods, such as AES or DES, are typically faster and better suited for encrypting large amounts of data, which is why they’re widely used for bulk encryption. The trade-off is key distribution and management—the secret key must be kept secure and exchanged safely. Hashing is a different concept altogether and is not reversible encryption, so it isn’t describing how symmetric encryption works.