Which term describes a cryptanalysis technique involving an exhaustive search of all possibilities?

Which term describes a cryptanalysis technique involving an exhaustive search of all possibilities?

• A. Dictionary attack
• B. Brute force
• C. Rainbow table attack
• D. Side-channel attack

Answer: (B)

Exhaustive search of all possible inputs is what a brute force approach does. It tries every key or password in the entire key space until the correct one is found. This method doesn’t depend on any weakness in the cryptosystem or on precomputed data; its success is guaranteed in principle because the right input is somewhere in the space. How practical it is depends on the size of that space—the longer the key, the more possibilities, and the longer it takes, often making it infeasible with strong modern keys. Other techniques use different ideas: a dictionary attack relies on a precompiled list of common passwords rather than all possibilities; a rainbow table attack uses huge precomputed tables to reverse hashes; a side-channel attack exploits information leaked during the device’s operation rather than breaking the cryptography itself.

Exhaustive search of all possible inputs is what a brute force approach does. It tries every key or password in the entire key space until the correct one is found. This method doesn’t depend on any weakness in the cryptosystem or on precomputed data; its success is guaranteed in principle because the right input is somewhere in the space. How practical it is depends on the size of that space—the longer the key, the more possibilities, and the longer it takes, often making it infeasible with strong modern keys. Other techniques use different ideas: a dictionary attack relies on a precompiled list of common passwords rather than all possibilities; a rainbow table attack uses huge precomputed tables to reverse hashes; a side-channel attack exploits information leaked during the device’s operation rather than breaking the cryptography itself.