Consider the following pseudo-WEP protocol. The key is 4 bits and the IV is 2 bits. The IV is appended to the end of the key when generating the keystream. Suppose that the shared secret key is 1011. The keystreams for the four possible inputs are as follows:

1011 00: 1100101101010101001011010100100... 1011 01: 0110011011001010110100100101101... 1011 10: 1010111010111100010100101001111... 1011 11: 1111101010001000101010100010111...

Suppose all messages are 8-bits long and the ICV ( integrity check), and is calculated by XOR-ing the first 4 bits of data with the last 4 bits of data. Suppose the pseudo-WEP packet consists of three fields: first the IV field, then the message field, and last the ICV field, with last two fields encrypted.

(1) We want to send the message m = 11111001 using the above pseudo-WEP protocol with IV = 01. What will be the values of the ICV before encryption, the encrypted message, and the encrypted ICV?

(2) Briefly explain how confidentiality and message integrity are achieved in this pseudo-WEP pro- tocol.

(3) What is the weakness of WEP? Explain why.