ISC2 Exam ISSAP Topic 1 Question 49 Discussion

XORed with the plaintext blocks to get the ciphertext. With other stream ciphers, flipping a bit in the ciphertext produces a flipped bit in the

plaintext at the same location. This property allows many error correcting codes to function normally even when applied before encryption.

Answer option C is incorrect. In the cipher-block chaining (CBC) mode, each block of plaintext is XORed with the previous ciphertext block

before being encrypted.

Answer option D is incorrect. The propagating cipher-block chaining or plaintext cipher-block chaining (PCBC) mode is designed to cause small

changes in the ciphertext to propagate indefinitely when decrypting, as well as when encrypting.

Answer option B is incorrect. The cipher feedback (CFB) mode, a close relative of CBC, makes a block cipher into a self-synchronizing stream

cipher.