TR 102 153 V1 1 1 Electronic Signatures and ETSI Etsi Form

Instructions and help about TR 102 153 V1 1 1 Electronic Signatures And ETSI Etsi

The point of public key encryption is that the public key component is really public. That is, any user can send his or her public key to any other user or just broadcast it to the world. Although this approach is very convenient, it has a major weakness. That is, anyone can forge such a public announcement. Some user could pretend to be Bob, and send a public key to another user such as Alice, and tell Alice that this is Bob's public key. The result is that when Alice sends a private message to Bob saying she encrypts it using Bob's public key. But remember this Bob's public key is actually forged by the attacker. Then the message can be intercepted by the attacker, and can be read by the attacker. Now, at some point hopefully, Bob can discover that there's a forgery going on and a fake public key of his was being used. But then what can Bob do? Bob can send Alice another message saying that, hey, this is my real public key. But how could Alice tell? That is, how could Alice tell that