If we only know the period of a Stream Cipher, let's say 150-200 bit in length, how can we use this information to attack a stream cipher?
Taking a look at this link, What is the period of a cipher? I see that the period of the stream cipher is simply the amount of data we encrypt before starting the encryption over again.
From the attacker's stand point, this let's us know the chunk size of data we are encrypting but how does this help us attack the stream cipher? Won't we still need to know plaintext and cipher text?