Which of the following is a method for establishing non-repudiation?

Establishing non-repudiation ensures that parties in a transaction cannot deny their involvement in that transaction. Digital certificates play a central role in this process by providing a means of authenticating the identities of the parties involved.

Digital certificates are issued by trusted third parties known as Certificate Authorities (CAs). When a digital certificate is used, it incorporates encryption techniques to bind an individual’s identity to a public key, enabling secure and verified communications. This association helps prevent denial of participation in digital transactions. If a person, for example, uses a digital certificate to sign a document, they cannot later claim that they did not sign it, because the digital signature created using their private key can be verified using their public key contained within the certificate.

In contrast, email notifications, while useful for communication, do not inherently provide proof of identity or cannot confirm that a message was received or acknowledged. Encryption primarily serves the purpose of securing data in transit or at rest but does not offer definitive proof of who sent or received information. Data backups are critical for data recovery and integrity but do not establish non-repudiation between parties. Therefore, the use of digital certificates is the most effective method among the provided choices to establish non-repudiation.