network security

Question

suppose that a message has been encrypted using DES in chipertext block chaining mode. One bit of chipertext in block Ci is accedntally transformed from 0to 1during transmissin. How much plaintext will be grabled as a result?

 

a)1

b)2

c)n-

d)n-i+1

Answer 1

In ciphertext block chaining the ciphertext of a block depends on the previous blocks.

As the block number 'i' is changed so the next 'n-i+1' blocks will be affected.