Which statement best describes how public-key encryption maintains confidentiality?

Which statement best describes how public-key encryption maintains confidentiality?

• A. Data encrypted with the private key can be decrypted with the public key.
• B. Data is transmitted unencrypted but hidden behind TLS.
• C. Data is secret on the server and never transmitted.
• D. Data encrypted with the public key can be decrypted only with the private key.

Answer: (D)

Public-key encryption keeps messages confidential by using two keys: a public key that anyone can use to encrypt, and a private key that only the recipient keeps to decrypt. When you encrypt data with the public key, only the holder of the private key can undo that encryption and read the original message. That ownership of the private key is what ensures secrecy even if the ciphertext travels across an open network. So the statement that data encrypted with the public key can be decrypted only with the private key best describes how confidentiality is maintained. The other ideas describe signing (encrypting with the private key so others can verify), relying on TLS for transport security, or keeping data on a server, none of which capture the core way public-key encryption protects content.

Public-key encryption keeps messages confidential by using two keys: a public key that anyone can use to encrypt, and a private key that only the recipient keeps to decrypt. When you encrypt data with the public key, only the holder of the private key can undo that encryption and read the original message. That ownership of the private key is what ensures secrecy even if the ciphertext travels across an open network. So the statement that data encrypted with the public key can be decrypted only with the private key best describes how confidentiality is maintained. The other ideas describe signing (encrypting with the private key so others can verify), relying on TLS for transport security, or keeping data on a server, none of which capture the core way public-key encryption protects content.