The probability that Alice sends a message to Bob encrypted with a weak key is .05. Eve has the technical ability to intercept messages. After having intercepted 4 messages encrypted with strong keys, what is the probability that the fifth message intercepted by Eve is encrypted with a weak key? How many messages will Eve have to intercept to have the hope of running into a message encrypted with a weak key? Hint: use math expectation Solution (.95)*(.95)*(.95)*(.95)*(.05) = .0407253125 the mean of a distribution like this is simply n*p since we want the mean to be 1 we will solve for p so 1 = n*.05 divide both sides by .05 and we get that n = 20.

1. The probability that Alice sends a message to Bob encrypted with a weak key
is .05. Eve has the technical ability to intercept messages. After having
intercepted 4 messages encrypted with strong keys, what is the probability that
the fifth message intercepted by Eve is encrypted with a weak key?
How many messages will Eve have to intercept to have the hope of running into a
message encrypted with a weak key? Hint: use math expectation
Solution
(.95)*(.95)*(.95)*(.95)*(.05) = .0407253125 the mean of a distribution like this is
simply n*p since we want the mean to be 1 we will solve for p so 1 = n*.05 divide both sides by
.05 and we get that n = 20