Problem
During WEP authentication, the access points sends a random challenge value to the station. The station must send back the challenge value encrypted with the shared key (and the IV, which is sent in the clear) to continue the process.
Suppose an adversary is attempting a masquerade attack on an access point which is using the original version of WEP. When a challenge value is received from the access point, adversary's system generates a pseudorandom key value to encrypt the challenge value.
What is the probability of a successful attack using this process? Express your result as "1 in x" where x is a number in scientific format. Show your calculations.