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1 \documentclass{article} |
1 \documentclass{article} |
2 \usepackage{../style} |
2 \usepackage{../style} |
3 \usepackage{../langs} |
3 \usepackage{../langs} |
4 |
4 |
5 \begin{document} |
5 \begin{document} |
6 \fnote{\copyright{} Christian Urban, King's College London, 2014, 2016} |
6 \fnote{\copyright{} Christian Urban, King's College London, 2014, 2016, 2017} |
7 |
7 |
8 %% the expectation is that anything encrypted today, will be |
8 %% the expectation is that anything encrypted today, will be |
9 %% decrypted in 20 years time |
9 %% decrypted in 20 years time |
10 |
10 |
11 %http://www.net.in.tum.de/fileadmin/TUM/teaching/netzsicherheit/ws1516/07_PKI.pdf |
11 %http://www.net.in.tum.de/fileadmin/TUM/teaching/netzsicherheit/ws1516/07_PKI.pdf |
359 replayed, because $A$ would send out each time a fresh nonce. |
359 replayed, because $A$ would send out each time a fresh nonce. |
360 So with this protocol you can ensure also for $A$ that it |
360 So with this protocol you can ensure also for $A$ that it |
361 talks to $B$. I leave you to argue that $B$ can be sure to |
361 talks to $B$. I leave you to argue that $B$ can be sure to |
362 talk to $A$. Of course these arguments will depend on the |
362 talk to $A$. Of course these arguments will depend on the |
363 assumptions that only $A$ and $B$ know the key $K_{AB}$ and |
363 assumptions that only $A$ and $B$ know the key $K_{AB}$ and |
364 that nobody can break the encryption unless they have this key |
364 that nobody can break the encryption |
365 and that the nonces are fresh each time the protocol is run. |
365 and that the nonces are fresh each time the protocol is run. |
366 |
366 |
367 The purpose of the nonces, the random numbers that are sent |
367 The purpose of the nonces, the random numbers that are sent |
368 around, might be a bit opaque. Because they are unpredictable |
368 around, might be a bit opaque. Because they are unpredictable |
369 they fulfil an important role in protocols. Suppose |
369 they fulfil an important role in protocols. Suppose |