Cisco Cyber Security Practice Exam

What are key elements needed to implement HMAC effectively?

1. Secret key and message digest

2. Public key and system log

3. Session ID and timestamp

4. Random number and user input

The correct answer is: Secret key and message digest

To implement HMAC (Hash-based Message Authentication Code) effectively, it's essential to have a secret key and a message digest. The secret key serves as a critical component for ensuring that the message can only be authenticated by parties who possess the key, thereby maintaining the confidentiality and integrity of the data. The message digest, which is produced by hashing the message along with the secret key, creates a unique representation of the data. This process combines the hash function's properties with the secret key to provide both authenticity and integrity verification. If the message or the key is altered in any way, the resulting message digest will change, enabling the detection of tampering. The other options do not encompass the foundational elements necessary for HMAC. For instance, public keys and system logs do not provide the requisite method for creating a secure authentication code. Likewise, a session ID and timestamp or a random number and user input do not inherently involve secret keys or hashing processes that are crucial for the HMAC functionality. Therefore, it’s clear that having a secret key and message digest is fundamental for effectively implementing HMAC.