Which statement about increasing key length on brute-force resistance is illustrated by extending from 43 to 50 bits?

• A. It shortens brute-force time
• B. Has no effect
• C. Increases brute-force time
• D. Makes it impossible to crack

Answer: (C)

Increasing the key length boosts brute-force resistance because each additional bit doubles the number of possible keys. Extending from 43 to 50 bits adds seven bits, so the total key space grows from 2^43 to 2^50, a factor of 2^7 (128) more possibilities. Since a brute-force attack must try keys until it finds the correct one, the expected time to crack rises roughly by a factor of 128 under the same testing rate. This makes cracking significantly harder, though not impossible with enough time or massive parallel resources. The other options don’t fit because the brute-force effort would not shorten, would not remain unchanged, and it’s not rendered entirely crackproof just by this increase.