Non-repudiation in e-commerce is achieved through which methods?

• A. Digital signatures
• B. Confirmation services
• C. Timestamps
• D. All of the above

Answer: (D)

Non-repudiation means having credible evidence that a party carried out a transaction or sent a message and cannot later deny it. Digital signatures provide cryptographic proof of who signed the data and ensure its integrity, so the signer cannot dispute authorship. Confirmation services give verifiable acknowledgments that the other party received or approved the transaction, supplying explicit proof of participation. Timestamps record exactly when the action occurred, preventing denial of the timing of the event. Using all three together creates a strong, auditable trail from origin to receipt that supports non-repudiation in e-commerce.