Question

Which of the following is false for ECB mode of operation

i) The Plain text is broken into blocks of size 128 bytes

ii) Blocks can be swapped, repeated, replaced without recipient noticing

iii) Good for short data

iv) Encryption of each block is done separately using a randomly generated key for each block

(a) i) only

(b) ii) and iii)

(c) i) and iv)

(d) i) ii) and iv)

I had been asked this question in an international level competition.

The above asked question is from DES Modes of Operation topic in portion Advanced Encryption Algorithm and Block Cipher Operation of Cryptograph & Network Security

Answer 1

Correct option is (c) i) and iv)

To elaborate: Block size is 64 bits. The same Key is used for each block.