This problem provides a numerical ciphertext of encryption using a two-round version of DES.
We start with the same bit pattern for the master key K and the plaintext, namely:
Hexadecimal notation:
0 1 2 3 4 5 6 7 8 9 A B C D E F
Binary notation:
0000 0001 0010 0011 0100 0101
0110 0111 1000 1001 1010 1011
1100 1101 1110 1111
This is the encrypted form of M = 0123456789ABCDEF, namely,
C (ciphertext) = 85E813540F0AB405 (hexadecimal form)
QUESTION: Decrypt the ciphertext given and EXPLAIN all the steps.