Which ensures that an individual cannot deny sending a message and the recipient cannot deny receiving it?

Which ensures that an individual cannot deny sending a message and the recipient cannot deny receiving it?

• A. Non-Repudiation
• B. Confidentiality
• C. Availability
• D. Authenticity

Answer: (A)

Non-repudiation is the assurance that someone cannot deny a transaction. In messaging, it means the sender cannot deny sending and the recipient cannot deny receiving. This is usually achieved by binding the sender’s identity to the message with a digital signature created with the sender’s private key, which anyone can verify using the sender’s public key to confirm who sent it and that the content hasn’t been altered. A delivery receipt or acknowledgment, often backed by secure logs or a timestamp authority, provides concrete proof that the message was delivered and received. This combination creates an undeniable trail of evidence for both parties. The other concepts don’t provide this dual-denial protection: confidentiality hides the content from others, not who sent or received it; availability ensures access to resources, not the denial of involvement; authenticity confirms who something is from, but not whether either party can later deny involvement.

Non-repudiation is the assurance that someone cannot deny a transaction. In messaging, it means the sender cannot deny sending and the recipient cannot deny receiving. This is usually achieved by binding the sender’s identity to the message with a digital signature created with the sender’s private key, which anyone can verify using the sender’s public key to confirm who sent it and that the content hasn’t been altered. A delivery receipt or acknowledgment, often backed by secure logs or a timestamp authority, provides concrete proof that the message was delivered and received. This combination creates an undeniable trail of evidence for both parties. The other concepts don’t provide this dual-denial protection: confidentiality hides the content from others, not who sent or received it; availability ensures access to resources, not the denial of involvement; authenticity confirms who something is from, but not whether either party can later deny involvement.