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 x, we look at the 8 bit ASCII representation of x: b_7, b_6, b_3, b_2, b_1, b_0. The ciphertext C will be C = E_K (b_7, b_3, b_3, b_1) and this what A will transmit to B Is this a good scheme? i. Give a YES/NO answer. ii. If you said NO explain what you think is the single biggest weakness of the scheme