Password guessing with Brute force attack -


when key guessing, key length used in cipher determines practical feasibility of performing brute-force attack, longer keys exponentially more difficult crack shorter ones. cipher key length of n bits can broken in worst-case time proportional 2^n , average time of half that. average combination 2^n-1.

why formula 2^n consist of 2?

the key length measured in bits binary value. either 0 or 1, there's 2 different possible answers each position.

a key length of 1 can either 0 or 1. 2 possible combinations. can represented 2^1.

a key length of 2bits can 00, 01, 10, 11. 4 possible combinations, or 2^2.

the 2 constant, it's number of bits change.


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