For a string of bits S. let S' denote the complimentary string obtained by changing all the 0s to 1s and all the 1s to the 0s( equivalently S'=S xor 111111....).
show that if a DES(data encryption standard) key K encrypts P(plaintext) to C(cipher text) then K' encrypts P' to C'.
Is it possible to show this using cryptool?
If possible dont use mathematical proof otherwise show the mathematical proof.