Which description correctly defines symmetric encryption?

Which description correctly defines symmetric encryption?

• A. It uses two different keys for encryption and decryption
• B. It uses the same key for both encryption and decryption
• C. It creates a hash of the message
• D. It relies on a trusted third party

Answer: (B)

Symmetric encryption is defined by using the same key to both encrypt and decrypt data. The sender and receiver must share this secret key in advance and keep it secure, since anyone who has the key can both lock and unlock the message. This contrasts with using two different keys—one for encryption and a separate one for decryption—which is how asymmetric encryption works. It’s not about creating a hash, which is a one-way digest used for integrity checks and cannot be reversed to recover the original message. It also isn’t about relying on a trusted third party to manage keys; that relates to trust and key management, not the encryption method itself. In practice, symmetric encryption is fast and well-suited for securing large amounts of data, with secure key distribution being the main practical challenge.

Symmetric encryption is defined by using the same key to both encrypt and decrypt data. The sender and receiver must share this secret key in advance and keep it secure, since anyone who has the key can both lock and unlock the message. This contrasts with using two different keys—one for encryption and a separate one for decryption—which is how asymmetric encryption works. It’s not about creating a hash, which is a one-way digest used for integrity checks and cannot be reversed to recover the original message. It also isn’t about relying on a trusted third party to manage keys; that relates to trust and key management, not the encryption method itself. In practice, symmetric encryption is fast and well-suited for securing large amounts of data, with secure key distribution being the main practical challenge.