Which feature of Public Key Infrastructure (PKI) supports integrity checks?

The feature of Public Key Infrastructure (PKI) that supports integrity checks is digital signatures. Digital signatures provide a way to ensure that a message or document has not been altered during transmission and confirm the authenticity of the sender.

When a sender creates a digital signature, they use their private key to encrypt a hash of the message. This hash acts as a unique fingerprint of the data. The recipient, upon receiving the message and the signature, can decrypt the hash using the sender's public key. If the decrypted hash matches the hash of the received message, it confirms that the content has remained unchanged and verifies the authenticity of the sender. This process is crucial in establishing data integrity, as any modification to the original content would result in a different hash value, alerting the recipient to a potential integrity violation.

Other options like availability monitoring, key distribution, and bandwidth monitoring focus on different aspects of network and system security, such as ensuring that systems are up and running or managing the distribution of cryptographic keys, rather than directly addressing the integrity of information.