The act of intercepting the first message in a public key exchange and substituting a bogus key for the original key is an example of which style of attack?

Spoofing refers to masquerading as another entity, which can be a component of an MITM attack but doesn't describe the full interception and substitution process during a key exchange.

Hijacking typically involves taking control of an already established session or system, rather than manipulating the initial key exchange handshake.

A Man-in-the-Middle (MITM) attack occurs when an attacker secretly relays and potentially alters communication between two parties who believe they are communicating directly. In a public key exchange, the attacker replaces the legitimate public key with their own, enabling them to decrypt and re-encrypt all traffic between the two unsuspecting parties.

Social Engineering relies on psychological manipulation of individuals, not on the technical interception and substitution of cryptographic keys.

A Distributed Denial of Service (DDoS) attack aims to overwhelm a system to disrupt its availability, which is entirely different from intercepting and manipulating a public key exchange.