Trust and certificates
In this and the previous chapters, we learned how public-key cryptography allows us to have secure communication with another person over an untrusted channel, and how, with digital signatures, we also get integrity, authentication, and non-repudiation. All those things are excellent; yet, before we end our dissertation around this topic, there's one last thing we need to cover.
The problem of trusting keys
Let's assume you need to send some confidential information to your friend Alex over the Internet, so you decide to build a solution that uses public-key cryptography. Before you can send Alex a message, you know you need to ask them for their public key. You decide that, for increased security, you want Alex to send you their public key in a message that is signed with their private key (that is, Alex's message contains their public key and a signature that can be verified with the very same public key). This will act as a guarantee that...
