In the OpenSSL command `openssl x509 -req -days 365 -in conestoga.csr -CA infinityca.crt -CAkey infinityca.key -CAcreateserial -out conestoga.crt`, what is the purpose of `-CAkey infinityca.key`?

### Why this is right The `-CAkey` option points to the CA’s private-key file. OpenSSL uses that key to sign the certificate being issued from the request. The CA certificate itself is supplied separately with `-CA`. ### The concept The command takes a Certificate Signing Request (CSR) as input, uses the CA certificate and CA private key to issue a certificate, and writes the result to the output file. The `-CA` file supplies CA certificate information, including its public key, while `-CAkey` supplies the secret signing key. The server’s private key is not copied into the certificate; certificates contain public keys. Protecting the CA private key matters because it is used to create certificates that may be trusted by systems accepting the CA. ### The other options - **It identifies the server private-key file to be copied into the certificate.**: The server private key should remain secret and is not inserted into a certificate. - **It selects the CA certificate file used to verify the server certificate.**: The CA certificate is supplied by `-CA`, not `-CAkey`. - **It creates the server’s Certificate Signing Request (CSR).**: A CSR is created in an earlier step, before the certificate-signing command. ### Terms - **OpenSSL**: A software toolkit used for cryptographic operations and certificate handling. - **Certificate Signing Request (CSR)**: A request containing the server’s public key and subject information. - **Certificate Authority (CA)**: An entity that signs certificates. - **Private key**: A secret key used here by the CA to sign the issued certificate. - **Certificate**: A signed record binding a subject to a public key. ### Remember In this command, `-CAkey` names the CA’s signing key; `-CA` names the CA certificate.