Which basic cryptographic service provides confidentiality?

• A. Data integrity
• B. Confidentiality
• C. Ident and Authen
• D. Non-repudiation

Answer: (B)

Confidentiality is the service that ensures only authorized parties can read the data. It’s achieved by encryption, which turns plaintext into ciphertext using a key; someone needs the key to decrypt and read the original message. This protects information from eavesdroppers even if it’s intercepted or accessed by an unauthorized party, whether the data is in transit or at rest. The other concepts address different security goals: data integrity ensures the data hasn’t been altered, identification and authentication verify who is communicating, and non-repudiation prevents a sender from denying they sent a message.