In the context of PKI, which of the following is a requirement for achieving non-repudiation?

In the context of Public Key Infrastructure (PKI), achieving non-repudiation primarily relies on the use of digital signatures. Non-repudiation ensures that a party in a digital transaction cannot deny the authenticity of their signature on a document or the sending of a message. This is critical in building trust in electronic communications and transactions.

Digital signatures provide this assurance by using a person's private key to sign a document or message, creating a unique cryptographic hash. The corresponding public key can be used by anyone to verify that the signature was generated by the holder of the corresponding private key and that the document was not altered after it was signed. This process not only confirms the identity of the signatory but also ensures that the signatory cannot later claim they did not sign the document, thus fulfilling the requirement for non-repudiation.

While encryption keys, public keys, and certificate requests play important roles in the overall functioning of PKI and secure communications, they do not directly provide the necessary functionality to ensure non-repudiation on their own. Encryption keys are primarily used for confidentiality, public keys are utilized for secure communications, and certificate requests are part of the process for obtaining a digital certificate but do not inherently provide proof of signature or identity