This brings us to the end of unit 3.
As long as we have a channel with integrity, we have a solution to our key distribution problem.
We can use the Diffie-Hellman protocol where at the end of the protocol
we've established a shared secret.
Once we're established that shared key we can use it to send messages,
using our symmetric encryption operations from the previous two units.
We still haven't solved many of the important problems that Diffie and Hellman identified
in this 1976 paper.
The one that I highlighted at the beginning was digital signatures.
We can't do digital signatures this way because the key is shared between Alice and Bob.
That couldn't be used to sign something since either Alice or Bob
would be able to make that signature.
To have digital signatures, what we need is asymmetric crypotography.
That's the main topic for Unit 4. Hope to see you there.
