ABSTRACT
The private-key encryption schemes are further illustrated in this chapter. Block ciphers themselves are not secure encryption schemes, but rather building blocks to construct secure private-key encryption schemes. To achieve security, block ciphers are run in certain modes of operations including ECB, CBC, and CTR mode. It concludes that the ECB mode is not IND-CPA secure while CBC and CTR are IND-CPA secure. This is followed by a stronger security notion, i.e., security against a chosen ciphertext attack and some examples which are CPA-secure but not CCA-secure.
