Which statement best describes AEAD modes like GCM?

• A. They provide confidentiality and integrity for the ciphertext and associated data
• B. They provide only confidentiality
• C. They provide only integrity
• D. They provide key management

Answer: (A)

AEAD modes like GCM combine encryption with authentication, giving both secrecy for the message and a way to verify that the message and any related data haven’t been tampered with. The ciphertext remains confidential, and an authentication tag ensures integrity for the ciphertext as well as for any associated data that’s processed together with it. That combination—confidentiality plus integrity for both the encrypted data and the associated data—best fits what AEAD modes provide. They don’t merely offer confidentiality, nor only integrity, and key management is a separate concern from the mode itself.