A recipient has the sender's public key and a signed document. Which action matches the verification step shown in the material?

### Why this is right Verification uses the public key associated with the sender’s private signing key and checks the signature against the document supplied. The command in the material specifies both the signature file and the document being checked. ### The concept **Verification** is a check that determines whether a signature is valid for a particular document under a particular public key. In the example, the recipient runs `openssl dgst -sha256 -verify public.pem -signature document.sha256 document.txt`. The command checks the signature file against the contents of `document.txt`; a changed document should not pass the same check. The filename itself is only a label and does not prove who signed a file. Verification also does not conceal the document or prove that the signed message is new. ### The other options - **B. Use the public key to create a replacement signature**: the public key is used for verification in this workflow; signing is done with the private key. - **C. Use the private key to decrypt the document**: the material describes signature verification, not decrypting the document, and the recipient uses the public key. - **D. Use the document's filename to confirm who signed it**: filenames can be chosen freely and are not cryptographic proof of origin. ### Terms - **Verification**: checking whether a signature is valid for a given document and public key. - **OpenSSL**: software that provides cryptographic tools, including the command-line operations shown in the material. - **SHA-256**: Secure Hash Algorithm 256, the hash algorithm named in the example command. - **Hash**: a compact value calculated from data and used by the signature process to detect changes. - **PEM**: Privacy-Enhanced Mail, a text-based format used for the example key files. ### Remember Verify the signature against the actual document, not merely its name or appearance.