}}</ref><ref name="ECRYPT">{{cite techreporttech report |author1 = Christophe De Cannière |author2 = Joseph Lano |author3 = Bart Preneel |title = Comments on the Rediscovery of Time/Memory/Data Trade-off Algorithm |institution = ECRYPT Stream Cipher Project |number = 40 |year = 2005 |url = http://www.ecrypt.eu.org/stream/papersdir/040.pdf }}</ref> When the IV is chosen at random, the probability of collisions due to the [[birthday problem]] must be taken into account. Traditional stream ciphers such as [[RC4]] do not support an explicit IV as input, and a custom solution for incorporating an IV into the cipher's key or internal state is needed. Some designs realized in practice are known to be insecure; the [[Wired Equivalent Privacy|WEP]] protocol is a notable example, and is prone to related-IV attacks.
