Protocol Game

In case you've missed them, check first the introduction.

Interactive game

We now introduce the console, so that you can execute yourself the different commands of the attackers!

Let us start with four simple network control commands:

• encrypt(fact, key): if E knows both fact and key, then E will know {fact}key;
• decrypt({fact}key, key): if E knows both {fact}key and key, then E will know fact;

For instance, let us consider the following protocol:

Knowledge: A:[s, hello], B:[K], E:[fake]
Steps:

1. A -> B: hello
2. B -> A: #K
3. A -> B: {#s}K

Can you figure out a way for E to know the session secret? Can you figure out a way for B to know "fake"?

The next exercise considers a simple server key protocol.