a) Suppose your professor wanted to distribute some code to all members of your class. Assume your professor is unquestionably trustworthy. Your professor invents a scheme by which she will denote that her code is safe to use. Before distributing the code, she will send a not to everyone saying she is about to post program P1, so when you find P1 on your class's server you can trust it. How could Mel, a malicious student, sneak in his own malicious code under that model?

b) Continuing the previous question, suppose your professor added that the first 4 bytes of P were abcd. How could Mel sneak in his code under that model?