: DES Cipher

Take a gray$-$level image of $8$ bit depth in pgm format $($or some other simple image format

that directly represents the gray values without complicated encoding$).$ Take DES and

encrypt the image $($using ECB mode or CBC mode$).$

a$.($Brutal force attack $-25$ points$)$ Try a brutal force attack on the ciphertext. Plot the

relationship between key length and time consumed for the attack. $($Since keys for DES

are of $56-$bit, you can simulate a key of n$-$bit $($n$<56)$ by fixing the remaining $56-$n bits.$).$

You may want to use diff and time shell command in Unix$/$Linux$.$ No need to plot for all

the key lengths, but the curve should be able to show the trend.