To answer this question, we need to understand the concept of side channel attacks.
Option A) Back Attack - This option is incorrect because there is no specific attack known as a "back attack" in the context of cryptography.
Option B) Unknown Attack - This option is incorrect because the term "unknown attack" does not specifically refer to attacks based on information gained from the physical implementation of a crypto system.
Option C) Reverse Attack - This option is incorrect because the term "reverse attack" does not specifically refer to attacks based on information gained from the physical implementation of a crypto system.
Option D) Side Channel Attack - This option is correct. A side channel attack is an attack on a cryptographic system that is based on information gained from the physical implementation of the system, rather than relying on brute force or algorithm weaknesses. Side channel attacks exploit unintended side effects of a system's implementation, such as timing information, power consumption, electromagnetic radiation, or sound, to gain information about the secret key or plaintext.
The correct answer is D) Side Channel Attack. This option is correct because it accurately describes an attack that is based on information gained from the physical implementation of a crypto system.