Which of the following is required to verify the authenticity of a digitally signed document?

While a digital hash is part of the signing process internally, possessing only the hash of the signed document is insufficient to verify authenticity without the sender's public key to decrypt and compare it.

The sender's private key is used to create the digital signature, not to verify it; exposing the private key to the recipient would compromise the entire security model of asymmetric cryptography.

To verify a digital signature, the recipient uses the sender's public key (not the recipient's public key) to decrypt the signature and obtain the original hash, which is then compared against a freshly computed hash of the document. If the hashes match, the signature is authentic and the document has not been tampered with. This asymmetric process ensures only the holder of the corresponding private key could have created the signature.

A shared secret is associated with symmetric cryptography and HMAC-based authentication schemes, not with asymmetric digital signature verification, which relies on a public/private key pair.