Queston 1:

In block cipher required where each 64-bit block is encrypted and decrypted independently

	a	CBC cipher block chaining
	b	ECB electronic Codebook
	c	Cipher feedback
	d	Output feedback

Which from the following is describe Cipher Block Chaining Mode CBC, where is P_j and P_j-1 are plaintext and previous plaintext, and C_j and C_j-1 ciphertext and previous cipher text, K is a key and E encryption function

	a	Cj = E(K, [Cj-1 XOR Pj])
	b	Cj = E(K, Pj)
	c	Cj = Pj_ E(K, [Cj-1 XOR Pj-1])
	d	None of above