Which mode of DES is the weakest?

A.
CFB

B.
OFB

C.
ECB

D.
CDC

Explanation:
Answer C is correct; ECB is Electronic Code Book, the simplest form of DES. It uses no initialization vector or chaining.

Incorrect Answers and Explanations: A, B, and D: Answers A, B, and D are incorrect. Cipher Feedback, Output Feedback, and Cipher Block Chaining all use initialization vectors and chaining or feedback.