Why use symmetric encryption for bulk data?

• A. It offers strong non-repudiation
• B. It encrypts with a public key
• C. It is slower for bulk data
• D. It is faster and more efficient for bulk data

Answer: (D)

Symmetric encryption is faster and more efficient for bulk data because it uses a shared secret key and streamlined algorithms that require less computation per byte. This makes encrypting and decrypting large files or streams quick and CPU-friendly. As a result, for big data, symmetric methods outperform asymmetric ones, which rely on heavier mathematical operations and are slower for large volumes. In real systems, a common approach is to encrypt the actual data with a symmetric key and then protect that key with asymmetric encryption to securely share it—combining speed for the data with secure key exchange. Non-repudiation isn’t provided by symmetric encryption since the same key is used by both parties, and public-key encryption is not what’s being used for bulk data.