Match each public-key infrastructure (PKI) or cryptographic component with its primary role: Components: 1. Recipient's public key 2. Recipient's private key 3. Certificate Authority (CA) 4. Cryptographic hash function Roles: A. Issues digital certificates that bind entities to their public keys B. Decrypts data or recovers session keys encrypted for the recipient C. Generates a fixed-length digest to detect data alteration and verify integrity D. Encrypts a confidential message or session key intended for the recipient

### Why this is right Each item has a separate role: the public key is shareable, the private key is secret, the certificate authority vouches for identity-to-key binding, and the hash fingerprints data. ### The concept | Item | Matches | Why | |---|---|---| | Recipient’s public key | Encrypts a confidential message or protects its session key | A sender can use the recipient’s public key without learning the private key. | | Recipient’s private key | Decrypts the message or recovers its protected session key | Only the recipient should control this secret key. | | Certificate Authority (CA) | Issues certificates that bind identities to public keys | The certificate helps others assess whether a public key belongs to the claimed party. | | Hash | Fingerprint used to check whether data has changed | Comparing the expected and calculated hashes can reveal alteration. | ### The pairs The table shows how public and private keys work together and distinguishes their use from certificates and hashes. ### Terms - **Certificate Authority (CA)**: A trusted entity that issues digital certificates. - **Hash**: A one-way data fingerprint. - **Public key**: The shareable key in a public/private pair. - **Private key**: The secret key in that pair. ### Remember The public key can be shared; the private key must remain secret.