In the described digital-signature process, which key does the sender use to create the signature?

### Why this is right The sender creates the signature with the private key, which is kept under the sender’s control. The recipient checks it with the corresponding public key, so the two operations use different keys. ### The concept A **digital signature** is cryptographic information attached to a document so a recipient can check whether the signed content has changed and whether it was signed using the private key associated with a public key. A **key pair** consists of related private and public keys. The private key must be protected because someone who obtains it may be able to create signatures that appear to come from its owner. The public key can be given to recipients so they can verify signatures. Signing does not, by itself, hide the document’s contents. ### The other options - **B. The sender's public key**: the public key is used for verification in this workflow, not signature creation. - **C. The recipient's public key**: a recipient’s public key is not the sender’s signing key; it is associated with the recipient. - **D. A shared secret key**: this describes a symmetric-key approach, whereas the described signature process uses a private and public key pair. ### Terms - **Digital signature**: cryptographic data used to check a document’s origin and whether its contents have changed. - **Private key**: the key kept by its owner and used here to create a signature. - **Public key**: the corresponding key distributed to recipients for signature verification. - **Symmetric key**: a secret key shared by parties for cryptographic operations. ### Remember The sender signs with the private key; the recipient verifies with the matching public key.