Using the triple DES algorithm, which is the cipher text?
A. output derived from key K1
B. output derived from key K2
C. output derived from key K4
D. output derived from key K3

D. output derived from key K3

Explanation:

The cyphertext = EK3( DK2(EK1(plain text)))

And from the above, it is quite clear that in the case of the triple DES, the plain text is first encrypted using key 1, and then it is decrypted using the key 2. Finally, it is encrypted using the key 3, and this results in the final encrypted content, and which is the ciphertext. Thus, this clarifies that the output derived from the key k3 is the actual ciphertext, and hence the correct option for the above question is as mentioned above.