1- Developers often think of software quality in terms of faults and failures. Faults are problems, such as loops that never terminate or misplaced commas in statements, that developers can see by looking at the code. Failures are problems, such as a system crash or the invocation of the wrong function, that are visible to the user. Thus, faults can exist in programs but never become failures, because the conditions under which a fault becomes a failure are never reached. How do software vulnerabilities fit into this scheme of faults and failures? Is every fault a vulnerability? Is every vulnerability a fault?

2- Suggest a source of a very long sequence of unpredictable numbers. Your source must be something that both the sender and receiver can readily access but that is not obvious to outsiders and is not transmitted directly from sender to receiver.

3- What characteristics would make an encryption absolutely unbreakable? What characteristics would make an encryption impractical to break?