+ <div class="entry">
+ <div class="title">
+ <a href="http://people.skolelinux.org/pere/blog/A_fist_full_of_non_anonymous_Bitcoins.html">A fist full of non-anonymous Bitcoins</a>
+ </div>
+ <div class="date">
+ 29th January 2014
+ </div>
+ <div class="body">
+ <p>Bitcoin is a incredible use of peer to peer communication and
+encryption, allowing direct and immediate money transfer without any
+central control. It is sometimes claimed to be ideal for illegal
+activity, which I believe is quite a long way from the truth. At least
+I would not conduct illegal money transfers using a system where the
+details of every transaction are kept forever. This point is
+investigated in
+<a href="https://www.usenix.org/publications/login">USENIX ;login:</a>
+from December 2013, in the article
+"<a href="https://www.usenix.org/system/files/login/articles/03_meiklejohn-online.pdf">A
+Fistful of Bitcoins - Characterizing Payments Among Men with No
+Names</a>" by Sarah Meiklejohn, Marjori Pomarole,Grant Jordan, Kirill
+Levchenko, Damon McCoy, Geoffrey M. Voelker, and Stefan Savage. They
+analyse the transaction log in the Bitcoin system, using it to find
+addresses belong to individuals and organisations and follow the flow
+of money from both Bitcoin theft and trades on Silk Road to where the
+money end up. This is how they wrap up their article:</p>
+
+<p><blockquote>
+<p>"To demonstrate the usefulness of this type of analysis, we turned
+our attention to criminal activity. In the Bitcoin economy, criminal
+activity can appear in a number of forms, such as dealing drugs on
+Silk Road or simply stealing someone else’s bitcoins. We followed the
+flow of bitcoins out of Silk Road (in particular, from one notorious
+address) and from a number of highly publicized thefts to see whether
+we could track the bitcoins to known services. Although some of the
+thieves attempted to use sophisticated mixing techniques (or possibly
+mix services) to obscure the flow of bitcoins, for the most part
+tracking the bitcoins was quite straightforward, and we ultimately saw
+large quantities of bitcoins flow to a variety of exchanges directly
+from the point of theft (or the withdrawal from Silk Road).</p>
+
+<p>As acknowledged above, following stolen bitcoins to the point at
+which they are deposited into an exchange does not in itself identify
+the thief; however, it does enable further de-anonymization in the
+case in which certain agencies can determine (through, for example,
+subpoena power) the real-world owner of the account into which the
+stolen bitcoins were deposited. Because such exchanges seem to serve
+as chokepoints into and out of the Bitcoin economy (i.e., there are
+few alternative ways to cash out), we conclude that using Bitcoin for
+money laundering or other illicit purposes does not (at least at
+present) seem to be particularly attractive."</p>
+</blockquote><p>
+
+<p>These researches are not the first to analyse the Bitcoin
+transaction log. The 2011 paper
+"<a href="http://arxiv.org/abs/1107.4524">An Analysis of Anonymity in
+the Bitcoin System</A>" by Fergal Reid and Martin Harrigan is
+summarized like this:</p>
+
+<p><blockquote>
+"Anonymity in Bitcoin, a peer-to-peer electronic currency system, is a
+complicated issue. Within the system, users are identified by
+public-keys only. An attacker wishing to de-anonymize its users will
+attempt to construct the one-to-many mapping between users and
+public-keys and associate information external to the system with the
+users. Bitcoin tries to prevent this attack by storing the mapping of
+a user to his or her public-keys on that user's node only and by
+allowing each user to generate as many public-keys as required. In
+this chapter we consider the topological structure of two networks
+derived from Bitcoin's public transaction history. We show that the
+two networks have a non-trivial topological structure, provide
+complementary views of the Bitcoin system and have implications for
+anonymity. We combine these structures with external information and
+techniques such as context discovery and flow analysis to investigate
+an alleged theft of Bitcoins, which, at the time of the theft, had a
+market value of approximately half a million U.S. dollars."
+</blockquote></p>
+
+<p>I hope these references can help kill the urban myth that Bitcoin
+is anonymous. It isn't really a good fit for illegal activites. Use
+cash if you need to stay anonymous, at least until regular DNA
+sampling of notes and coins become the norm. :)</p>
+
+<p>As usual, if you use Bitcoin and want to show your support of my
+activities, please send Bitcoin donations to my address
+<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&label=PetterReinholdtsenBlog">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
+
+ </div>
+ <div class="tags">
+
+
+ Tags: <a href="http://people.skolelinux.org/pere/blog/tags/bitcoin">bitcoin</a>, <a href="http://people.skolelinux.org/pere/blog/tags/english">english</a>, <a href="http://people.skolelinux.org/pere/blog/tags/personvern">personvern</a>, <a href="http://people.skolelinux.org/pere/blog/tags/sikkerhet">sikkerhet</a>.
+
+
+ </div>
+ </div>
+ <div class="padding"></div>
+
+ <div class="entry">
+ <div class="title">
+ <a href="http://people.skolelinux.org/pere/blog/Bitcoin_er_ikke_anonymt___f_res_Stortinget_bak_lyset_av_finansministeren_.html">Bitcoin er ikke anonymt - føres Stortinget bak lyset av finansministeren?</a>
+ </div>
+ <div class="date">
+ 22nd April 2013
+ </div>
+ <div class="body">
+ <p><a href="http://bitcoin.org/">Bitcoin</a> er mye i mediene for
+tiden. Jeg følger med via Mylder for å finne
+<a href="http://mylder.no/?drill=bitcoin">artikler som omtaler
+temaet</a>, og takket være dette oppdaget jeg at stortingsrepresentant
+Ketil Solvik-Olsen fra FrP nylig har spurt finansminister Sigbjørn
+Johnsen om hans syn på Bitcoin, og
+<a href="http://www.stortinget.no/no/Saker-og-publikasjoner/Sporsmal/Skriftlige-sporsmal-og-svar/Skriftlig-sporsmal/?qid=57052">fått
+svar for noen dager siden</a>. Jeg bet meg spesielt merke til
+følgende formulering fra finansministeren:</p>
+
+<p><blockquote>
+«Det er også utfordringer ved at handel med Bitcoins er uregulert og
+at transaksjonene er anonyme.»
+</blockquote></p>
+
+<p>At Bitcoin er anonymt er en myte som spres av både journalister og
+andre, så det er ikke veldig overraskende at også finansministeren har
+gått på limpinnen. Det er dog litt rart, da jeg håper at
+finansdepartementet ikke baserer seg på rykter og myter når de
+besvarer Stortinget. Men du trenger ikke bare tro på meg som kilde
+til påstanden om at Bitcoin ikke er anonymt. Sondre Rønjom har
+<a href="http://blogg.nsm.stat.no/archives/3241">via Sikkerhetsbloggen
+hos Nasjonal Sikkerhetsmyndighet</a> uttalt følgende:</p>
+
+<p><blockquote>
+«At [bitcoin] i utgangspunktet
+<a href="http://arxiv.org/abs/1107.4524"><em>ikke</em> er anonymt</a>,
+kommer kanskje som en overraskelse på mange.»
+</blockquote></p>
+
+<p>Enhver bevegelse av Bitcoin er offentlig tilgjengelig for alle på
+Internet, og en må legge svært mye innsats inn hvis en skal hindre at
+nettverksanalyse av transaksjonsloggene kan brukes til å identifisere
+brukerne. F.eks. kan en enkelt se hva jeg har mottatt til min
+offentliggjorte mottaksadresse ved å besøke blockexplorer og slå opp
+adressen
+<a href="http://blockexplorer.com/address/15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a>.
+Det virker dermed på meg ganske klart at å påstå at
+Bitcoin-transaksjoner er anonyme strengt tatt er å føre Stortinget bak
+lyset.</p>
+
+<p>Finansministeren er ikke den eneste som har latt seg forlede av
+medieomtalen. I spørsmålet fra Hr. Solvik-Olsen skriver han at «For
+noen dager siden kom den første bitcoin-minibanken på Kypros», hvilket
+så vidt jeg har klart å finne ut ikke er riktig. Det er annonsert
+planer om en slik minibank (fra
+<a href="http://www.bitcoinatm.com/">BitcoinATM</a>), men jeg finner
+intet tegn til at en slik minibank er utplassert noe sted.</p>
+
+<p>Som vanlig, hvis du bruker Bitcoin og ønsker å vise din støtte til
+mine aktiviteter, så setter jeg pris på Bitcoin-donasjoner til min
+adresse
+<b><a href="bitcoin:15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b&label=PetterReinholdtsenBlog">15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b</a></b>.</p>
+
+ </div>
+ <div class="tags">
+
+
+ Tags: <a href="http://people.skolelinux.org/pere/blog/tags/bitcoin">bitcoin</a>, <a href="http://people.skolelinux.org/pere/blog/tags/norsk">norsk</a>, <a href="http://people.skolelinux.org/pere/blog/tags/stortinget">stortinget</a>.
+
+
+ </div>
+ </div>
+ <div class="padding"></div>
+
projects / homepage.git / blobdiff