diff -r 3391a4fc3533 -r d58f8e3e78a5 handouts/ho07.tex --- a/handouts/ho07.tex Fri Jun 01 15:46:34 2018 +0100 +++ b/handouts/ho07.tex Sat Jun 09 21:01:46 2018 +0100 @@ -177,7 +177,7 @@ Did Alice intend to send him 10 Bitcoins, or did the message get duplicated by for example an attacker re-playing a sniffed message? What is needed is a kind of serial number for such -transactions. This means transaction messages shoul look more like +transactions. This means transaction messages should look more like \begin{center} $\{\text{I, Alice, am giving Bob Bitcoin \#1234567.}\}_{K^{priv}_{Alice}}$ @@ -277,7 +277,7 @@ transactions, but also to split outgoing transactions to potentially more than one receiver. The latter is also needed. Consider again the rightmost transactions in -Figure~\ref{txngraph} and suppose Alice is a coffeeshop owner +Figure~\ref{txngraph} and suppose Alice is a coffee shop owner selling coffees for 1 Bitcoin. Charles received a transaction from Zack over 5 Bitcoins, say. How does Charles pay for the coffee? There is no explicit notion of \emph{change} in the @@ -622,7 +622,7 @@ \subsubsection*{Bitcoins for Real} -Let us now turn to the nitty gritty details. As a participant +Let us now turn to the nitty-gritty details. As a participant in the Bitcoin network you need to generate and store a public-private key pair. The public key you need to advertise in order to receive payments (transactions). The private key @@ -642,7 +642,7 @@ forever) I would opt for the third option for anything except for trivial amounts of Bitcoins. As we have seen earlier in the course, securing a computer system that it can withstand a -targeted breakin is still very much an unsolved problem. +targeted break-in is still very much an unsolved problem. An interesting fact with Bitcoin keys is that there is no check for duplicate addresses. This means when generating a @@ -753,7 +753,7 @@ to pay with Bitcoins? Paying with paper money used to be a quite anonymous act (unlike paying with credit cards, for example). But this has changed nowadays: You cannot come to a -bank anymore with a suitcase full of money and try to open a +bank any longer with a suitcase full of money and try to open a bank account. Strict money laundering and taxation laws mean that not even Swiss banks are prepared to take such money and open a bank account. That is why Bitcoins are touted as @@ -830,7 +830,7 @@ located somewhere in the vicinity of the government's reach). This would impinge on what is called \emph{fungibility} of Bitcoins and make them much less attractive to baddies. Suddenly their - ``hard-earned'' Bitcoin money cannot be spent anymore. The attraction + ``hard-earned'' Bitcoin money cannot be spent any more. The attraction of this option is that this blacklisting can be easily done ``whole-sale'' and therefore be really be an attractive target for governments \& Co.