A X.509 public key certificate with the key usage attribute "non repudiation" can be used for which of the following?

Encrypting messages typically uses the 'key encipherment' or 'data encipherment' key usage attribute, not 'non-repudiation,' which is for signing.

The 'non-repudiation' key usage attribute in an X.509 certificate signifies that the private key corresponding to the public key in the certificate is intended for creating digital signatures. These signatures provide strong proof of origin and integrity, preventing the signatory from denying that they sent or approved a particular message or transaction.

Verifying signed messages uses the signer's public key, which is contained within the certificate, but the 'non-repudiation' attribute specifically applies to the private key's capability to sign, not the public key's capability to verify.

Decrypting encrypted messages uses the 'data encipherment' or 'key agreement' attributes for the private key, not 'non-repudiation.'