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consider a system that requires a 9 character password. restricted to a-z, A-Z, 0-9, ! ,* and requires the use of characters from at least 2 different categories. were the categories are (0-9 , !, and *),(a-z), (A-Z)

ASSUME rate of password crack as 20/second

a) assuming no feedback until each attempt had been completed, what is the expected time to discover password?

b) assuming feedback to the adversary flagging an error as each incorrect character is entered , what is the expected time to discover password?