A network consists of n hosts Assuming that cryptographic ke

A network consists of n hosts. Assuming that cryptographic keys are distributed on a per-host-pair basis, compute how many different keys are required.

Solution

a)
When every computer is linked to all others, you have a complete graph, which has (n(n-1))/2 edges.

For 6 computers, you would have (6*5)/2 = 15 keys.