Digital certificates are electronic documents that use public key cryptography to verify the identity and authenticity of the sender and the receiver of encrypted communications. Digital certificates are issued and signed by trusted entities called certificate authorities (CAs), and they contain information such as the public key, the name, and the expiration date of the certificate. Digital certificates enable network security devices to decrypt perimeter traffic and inspect it for command and control communications or other malicious activity. Reference:= Understanding Cisco Cybersecurity Operations Fundamentals (CBROPS) - Cisco, page 51.