Select ALL properties or checks supported by the digital-signature material.

### Why this is right - **The recipient can use the sender's public key to verify the signature** is true because verification uses the public key corresponding to the private key used for signing. - **A changed document should fail verification against the original signature** is true because the signature is checked against the document’s contents, so alteration changes what is being checked. ### The concept A **digital signature** supports checks of **authenticity** and **integrity**. Authenticity here means that verification links the signature to the private key corresponding to the public key used. Integrity means that the document being checked matches the signed content. Signing is not the same operation as encryption: the signature procedure described does not hide a document’s contents. A signature also does not, on its own, show whether a signed message is new or has been replayed. Those are distinct security goals and must not be inferred from a successful verification result. ### The other options - **C. The signing process automatically hides the document's contents**: this would be a confidentiality claim. The described procedure signs a file; it does not encrypt it. - **D. The signature alone proves that the message has never been reused**: a valid old signature can be copied with its original message, so freshness needs an additional check. ### Terms - **Authenticity**: assurance that data is associated with the expected sender’s signing key. - **Integrity**: assurance that the checked data has not changed relative to its signature. - **Encryption**: a process used to conceal data from people without the required key. - **Confidentiality**: protection against unauthorized reading of information. - **Replay**: reuse or resending of a previously valid message. ### Remember Signature verification checks origin-key association and content integrity, not secrecy or freshness.