4.16 LOOKING AHEAD

Channel coding addresses the first of two fundamental challenges in communication system design: reliability in the presence of noise.

The second challenge is security in the presence of adversaries. Channel coding protects against random physical-layer errors but does not defend against deliberate interception, impersonation, or manipulation. For example, a CRC can detect accidental corruption of a frame with extremely high probability, yet it provides no assurance of the sender’s identity and offers no protection against intentional modification by an attacker who can recompute the CRC. Achieving confidentiality, authenticity, and provable integrity requires cryptographic mechanisms.

The next chapter examines the security services required to protect information and systems against intentional threats. These services—confidentiality, integrity, availability, authentication, and non-repudiation—form the foundation of modern cybersecurity architectures. Cryptography provides the mathematical tools that enable these services, just as channel coding provides the tools for reliability. Together, error control and cryptographic protection form complementary pillars of secure and dependable communication systems.