A __________ cipher is one in which a block of plaintext is treated as a whole and used to produce a ciphertext block of equal length.
A)bit
B)product
C)stream
D)block

Question

Quizplus · Accepted Answer

A block cipher is a symmetric-key cipher that operates on fixed-length groups of bits, called blocks, with an unvarying transformation defined by a cipher key. It takes as input a block of plaintext and a key, and produces a block of ciphertext of the same size as the input block. The output of a block cipher is a function of the plaintext block and the key. This makes it difficult for an adversary without the key to obtain the original plaintext from the ciphertext.

A __________ Cipher Is One in Which a Block of Plaintext