concept Alice in category cryptography
This is an excerpt from Manning's book Real-World Cryptography MEAP V09.
Figure 1.1. Alice asks her (potentially malicious) messenger to deliver a confidential message to Bob.
This problem of finding ways to trust others (and their public keys), and making it scale, is at the center of real-world cryptography. A famous cryptographer was once heard saying "symmetric crypto is solved" to describe a field of research that had overstayed its welcome. And for the most part the statement was true. We seldom have issues encrypting communications, and we have strong confidence in the current encryption algorithms we use. Most engineering challenges when it comes to encryption are not about the algorithms themselves anymore, but about who Alice and Bob are, and how to prove it.
Same for Alice, how does she figure out if the public key she received truly is Bob’s public key? It’s possible that someone in the middle could have tampered with the first message as illustrated in figure 10.2.
Figure 10.2. Bob sends his public key to Alice so that she can use it to encrypt her messages to him. As nobody is authenticated, a man-in-the-middle attacker can simply replace Bob’s public key with their own.
