Consider a variant of the k-bit key and lock scheme described for memory protection whereby a process can access memory blocks for which every bit position set to 1 within the lock is also set to 1 in the process’s key.

a. How many unique locks are in the system?

b. Characterize all keys that access a memory block with the lock 01100110 for k = 8.

c. Show how this mechanism can be used to allow a process B to keep some memory blocks private, to share some with process A, and to share others with process C (but for which A and C do not share any memory blocks).