Ablock cipher:
A.
Converts a variable-length of plaintext into a fixed length ciphertext.
B.
Is an asymmetric key algorithm.
C.
Encrypts by operating on a continuous data stream.
D.
Breaks a message into fixed length units for encryption.
Explanation:
The correct answer is “Breaks a message into fixed length units for encryption”.
Answer “Encrypts by operating on a continuous data stream” describes a stream cipher.
Answer “Is an asymmetric key algorithm” is incorrect because a block cipher applies to symmetric
key algorithms; and answer “Converts a variable-length of plaintext into a fixed length ciphertext”
describes a hashing operation.