Eat the Cake! by Little Pwnie

Hi all, can someone PM me ? I unp****d using PE********. Now I am reversing, I think it is checking multiple bytes in the provided string, but not all of them…Do I have to guess the bytes which are not compared ?

EDIT → This box involves some guesswork from what I understand, solved it but 1-2 digits had to be guessed. Did anyone solve it without guessing ?