handouts/ho08.tex
changeset 367 3f0738fc8230
parent 366 34a8f73b2c94
child 371 690d778b9127
equal deleted inserted replaced
366:34a8f73b2c94 367:3f0738fc8230
   638 
   638 
   639 \begin{center}
   639 \begin{center}
   640 \url{http://bitcoinmagazine.com/13774/government-bans-professor-mining-bitcoin-supercomputer/}
   640 \url{http://bitcoinmagazine.com/13774/government-bans-professor-mining-bitcoin-supercomputer/}
   641 \end{center}
   641 \end{center}
   642 
   642 
   643 \noindent
   643 \noindent Bitcoin mining nowadays is only competitive, or
   644 Bitcoin mining nowadays is only competitive, or profitable,
   644 profitable, if you get the energy for free, or use special
   645 if you get the energy for free, or use special purpose 
   645 purpose computing devices. 
   646 computing devices.
   646 
       
   647 This about ``free'' energy can actually hurt you very badly in
       
   648 unexpected ways. You probably have heard about, or even used,
       
   649 Amazon's Elastic Compute Cloud (EC2). Essentially, Amazon is
       
   650 selling computing power that you can use to run your web site,
       
   651 for example. It is \emph{elastic} in the sense that if you
       
   652 have a lot of visitors, you pay a lot, if you have only a few,
       
   653 then it is cheap. In order to bill you they, you need to set
       
   654 up an account with Amazon and receive some secret keys in
       
   655 order to authenticate you. The clever (but also dangerous) bit
       
   656 is that you upload the code of your web site to GitHub and
       
   657 Amazon will pull it from there. You can probably already guess
       
   658 where this is going: in order to learn about Amazon's API, it
       
   659 gives out some limited computing power for free. Somebody used
       
   660 this offer in order to teach himself Ruby on Rails with a
       
   661 mildly practical website. Unfortunately, he uploaded also his
       
   662 secret keys to GitHub (this is really an easy mistake). Now,
       
   663 nasty people crawl GitHub for the purpose of stealing such
       
   664 secret keys. What can they do with this? Well, they quickly
       
   665 max out the limit of computing power with Amazon and mine
       
   666 Bitcoins (under somebody else's account). Fortunately for this
       
   667 guy, Amazon was aware of this scam and in a goodwill gesture
       
   668 refunded him the money the nasty guys incurred over
       
   669 night with their Bitcoin mining. If you want to read the
       
   670 complete story, google for ``My \$2375 Amazon EC2 Mistake''.
       
   671 
   647 
   672 
   648 \subsubsection*{Anonymity with Bitcoins}
   673 \subsubsection*{Anonymity with Bitcoins}
   649 
   674 
   650 One question one often hears is how anonymous is it actually
   675 One question one often hears is how anonymous is it actually
   651 to pay with Bitcoins? Paying with paper money used to be a
   676 to pay with Bitcoins? Paying with paper money used to be a
   652 quite anonymous act (unlike paying with creditcards, for
   677 quite anonymous act (unlike paying with credit cards, for
   653 example). But this has changed nowadays: You cannot come to a
   678 example). But this has changed nowadays: You cannot come to a
   654 bank anymore with a suitcase full of money and try to open a
   679 bank anymore with a suitcase full of money and try to open a
   655 bank account. Strict money laundering and taxation laws mean
   680 bank account. Strict money laundering and taxation laws mean
   656 that not even Swiss banks are prepared to take such money and
   681 that not even Swiss banks are prepared to take such money and
   657 open a bank account. That is why Bitcoins are touted as 
   682 open a bank account. That is why Bitcoins are touted as