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Explain the purpose and construction of HMAC (Hash-based MessageAuthentication Code). Compare it to a simple MAC construction like h(k ⊕ d),and describe the specific vulnerability (such as length-extension) that HMACaddresses and how it mitigates it. [8 Points]

A common XSRF defense that binds a token to the session ID using an HMAC (no extra server state) is called:

Compare ingress and egress filtering in packet-filtering firewalls. Using the DNS port 53 example, illustrate how a border firewall uses these rules to protect an internal trusted network.

Compare Signature-based IDS and Anomaly-based IDS in terms of detection approach, strengths, and drawbacks. Also briefly explain the difference between Host-based IDS (HIDS) and Network-based IDS (NIDS).

True or False: Application-specific mechanisms such as SSL/TLS and S/MIME provide security at the network layer for all applications.

The Origin header in cross-origin requests:

In RSA, d is computed such that:

Which PKI entity validates identity before a certificate is issued?

Describe the two main security protocols in IPSec (AH and ESP). For each, state what security services it provides (authentication, integrity, confidentiality, replay protection) and one scenario where it would be preferred over the other.

Bell-LaPadula enforces