48 |
48 |
49 \end{frame} |
49 \end{frame} |
50 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
50 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
51 |
51 |
52 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
52 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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53 \begin{frame} |
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54 \frametitle{Interlock Protocol} |
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55 |
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56 invented by Ron Rivest and Adi Shamir (198X?) |
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57 |
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58 \begin{center} |
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59 \begin{tabular}{ll@{\hspace{2mm}}l} |
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60 1. & $A \to B :$ & $K^{pub}_A$\smallskip\\ |
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61 2. & $B \to A :$ & $K^{pub}_B$\smallskip\\ |
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62 3. & & $\{A,m\}_{K^{pub}_B} \;\mapsto\; H_1,H_2$\\ |
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63 & & $\{B,m'\}_{K^{pub}_A} \;\mapsto\; M_1,M_2$\\ |
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64 4. & $A \to B :$ & $H_1$\smallskip\\ |
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65 5. & $B \to A :$ & $\{H_1, M_1\}_{K^{pub}_A}$\smallskip\\ |
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66 6. & $A \to B :$ & $\{H_2, M_1\}_{K^{pub}_B}$\smallskip\\ |
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67 7. & $B \to A :$ & $M_2$ |
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68 \end{tabular} |
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69 \end{center} |
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70 |
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71 \end{frame} |
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72 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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73 |
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74 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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75 \begin{frame} |
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76 \frametitle{Car \& Transponder} |
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77 |
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78 \begin{enumerate} |
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79 \item $C$ generates a random number $N$ |
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80 \item $C$ calculates $\{N\}_K \mapsto F,G$ |
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81 \item $C \to T$: $N, F$ |
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82 \item $T$ calculates $\{N\}_K \mapsto F',G'$ |
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83 \item $T$ checks that $F = F'$ |
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84 \item $T \to C$: $N, G'$ |
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85 \item $C$ checks that $G = G'$ |
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86 \end{enumerate} |
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87 |
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88 Does the car authenticate the transponder? Does the |
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89 transponder authenticate the car? |
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90 |
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91 \end{frame} |
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92 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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93 |
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94 |
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95 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
53 % student prticipation |
96 % student prticipation |
54 \begin{frame} |
97 %\begin{frame} |
55 \frametitle{Bitcoins} |
98 %\frametitle{Bitcoins} |
56 |
99 % |
57 \begin{center} |
100 %P2P, 21 Mio, $10^-8$, Mt~Gox, value decreased?, anonymity, |
58 \Huge\bf ? |
101 %Silk Road, verification incentive, puzzle, SHA-256, slow |
59 \end{center} |
102 %transactions, |
60 |
103 % |
61 \end{frame} |
104 %\end{frame} |
62 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
105 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
63 |
106 |
64 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
107 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
65 \begin{frame}[t] |
108 \begin{frame}[t] |
66 \frametitle{Bitcoins from 10,000m} |
109 \frametitle{Bitcoins from 10,000m} |
627 \end{frame} |
670 \end{frame} |
628 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
671 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
629 |
672 |
630 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
673 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
631 \begin{frame}[t] |
674 \begin{frame}[t] |
632 \frametitle{But I did not Inhale} |
675 \frametitle{But I did not Inhale\ldots} |
633 |
676 |
634 \begin{center} |
677 \begin{center} |
635 \includegraphics[scale=0.4]{../pics/bitcointornetwork.png} |
678 \includegraphics[scale=0.4]{../pics/bitcointornetwork.png} |
636 \end{center} |
679 \end{center} |
637 |
680 |
638 ledger is public forever; everybody can inspect |
681 \only<1>{ |
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682 ledger is public ``forever''; everybody can inspect |
639 how money was transferred from which address to |
683 how money was transferred from which address to |
640 which address |
684 which address; maybe not ideal for money laundering} |
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685 \only<2>{ |
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686 You should use a new pp-pair for \alert{every} transaction; |
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687 but few do (merchants). A design flaw(?): combining transactions.} |
641 |
688 |
642 \end{frame} |
689 \end{frame} |
643 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
690 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
644 |
691 |
645 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
692 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
646 \begin{frame}[t] |
693 \begin{frame}[t] |
647 \frametitle{Anonymity} |
694 \frametitle{Anonymity} |
648 \small |
695 \small |
649 |
696 |
650 Bitcoins may not be ideal for money laundering because all |
697 ``How anonymous is Bitcoin? Many people claim that Bitcoin can |
651 transactions are public. |
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652 |
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653 How anonymous is Bitcoin? Many people claim that Bitcoin can |
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654 be used anonymously. This claim has led to the formation of |
698 be used anonymously. This claim has led to the formation of |
655 marketplaces such as Silk Road (and various successors), which |
699 marketplaces such as Silk Road (and various successors), which |
656 specialize in illegal goods. However, the claim that Bitcoin |
700 specialize in illegal goods. However, the claim that Bitcoin |
657 is anonymous is a myth. The block chain is public, meaning |
701 is anonymous is a \underline{myth}. The block chain is public, |
658 that it’s possible for anyone to see every Bitcoin transaction |
702 meaning that it’s possible for anyone to see every Bitcoin |
659 ever. Although Bitcoin addresses aren’t immediately associated |
703 transaction ever. Although Bitcoin addresses aren’t |
660 to real-world identities, computer scientists have done a |
704 immediately associated to real-world identities, computer |
661 great deal of work figuring out how to de-anonymize |
705 scientists have done a great deal of work figuring out how to |
662 “anonymous” social networks. The block chain is a marvellous |
706 de-anonymize `anonymous' social networks. The block chain is a |
663 target for these techniques. |
707 marvellous target for these techniques.'' |
664 |
708 |
665 \end{frame} |
709 \end{frame} |
666 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
710 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
667 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
711 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
668 \begin{frame}[t] |
712 \begin{frame}[t] |
687 \end{center} |
731 \end{center} |
688 |
732 |
689 \end{frame} |
733 \end{frame} |
690 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
734 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
691 |
735 |
|
736 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
|
737 \begin{frame}[t] |
|
738 \frametitle{Take Home Points} |
|
739 |
|
740 |
|
741 \begin{itemize} |
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742 \item Don't gamble! I am not a first mover in such things. |
|
743 \item Cool idea, but I am sure there will be a Bitcoin~2.0. |
|
744 \item It still depends on a lot of old-fashioned security |
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745 (e.g.~keeping private-keys secret)\bigskip |
|
746 |
|
747 \item Having now the knowledge how it works, go back |
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748 and listen to what people/media make of it. |
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749 \end{itemize} |
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750 |
|
751 \end{frame} |
|
752 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
692 |
753 |
693 |
754 |
694 |
755 |
695 \end{document} |
756 \end{document} |
696 |
757 |