Consider the following encryption scheme to provide confiden

Consider the following encryption scheme to provide confidentiality. A and B share a secret key K for an encryption scheme E which works with 4 - bit blocks. A wants to send an English text message M to B. A is going to encrypt M one character at a time. To encrypt a single character s, we look at the 8 bit ASCII representation of x: b_7, b_6, b_3, b_4 b_3, b_2, b_2, b_1, b_0. The eiphertext C will be C = B_k (b_7, b_5, b_3, b_1) and this is what A will transmit to B Is this a good scheme? Give a YES/NO answer. If you said NO explain what you think is the single biggest weakness of the scheme.

Solution

This encryption scheme will works fine until intruder doesn\'t able to get the key. The biggest weakness is that if anyone taps the message in between transition none of the sender or receiver will be able to identify that and intruder will see the message.

Hope it helps, do give your response.