Randy can almost guess what the next two letters are going to be, but he has to keep working through the algorithm or the deck will get out of whack. He generates a 23 and then a 47 which, modulo 26, is 21, and subtracting the 23 and the 21 from the next two ciphertext letters K and J (again, modulo 26) gives him N and O as expected. So he has "DONO" deciphered. And continuing to work through it, one letter at a time, the cards getting a little sweaty in his hands now, he eventually gets DONOTUSEP and finally loses his place while trying to generate the last keystream letter. So now the deck is out of whack and completely unrecoverable, reminding him that he’d better be careful next time. But he can guess that this message must be: DO NOT USE PC. Enoch is worried that Randy did not anticipate Van Eck phreaking.