Assume that the ciphertext C is computed from the plaintext P by C= P ⊕ K1 ⊕ K2 , where K1 and K2 are the encryption key and ⊕ denotes the bitwise Xor operation. Also, we know that the ciphertext of P=5 is C=12. What is the encryption key?
a) 9
b) 10
c) 3
d) 0