Question

1. The key length in DES is 56-bits. If a hacker uses a parallel computer that can perform 10 billion guesses per second, estimate the average time (in days) it takes the hacker to find the key using brute-force method. (10 points)

Answer 1

Des algorithm is bit long.

So there are ​​​ keys.

Number of keys =  =

Speed of guess = 10 billion keys / second

= keys/ second

So total time = number of keys / speed of guess

=7.2 * 10^16 / 10^10

=7.2 *10 ^6

=7200000 seconds

=120000 minutes ( divide by 60)

=2000 hour ( divide by 60)

=83 days ( divide by 24)

It take 83 days to try all keys in brute force methode