

How can we catch a kidnapper if he demands a ransom in Bitcoin? - salehhamadeh

If the criminal wants cash, we can catch him by his geographic location. If he is stupid enough to ask for a check, we can catch him by the bank account that the money gets deposited to. However, if he asks for Bitcoins, there is no way we can track him. Any thoughts?
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informatimago
You can track the bitcoins, and as soon as a transaction occurs with a known
party, you can go back up the transaction chain.

It's just like with GSM IMEI, notably pre-paid GSM cards, they're identified
(in most countries), by an ID card when you buy the pre-paid card. If people
wanted anonymity, they'd have to swap their pre-paid card randomly and
anonymously in the street.

If you want anonymity with bitcoins, you will have to swap them on paper, in
the street.

And even having shuffled bitcoins, you'd have to be very careful, because
there are other ways to identify entities, based on their behavior. See for
example:

[https://hal.archives-
ouvertes.fr/file/index/docid/718763/fil...](https://hal.archives-
ouvertes.fr/file/index/docid/718763/filename/TR.pdf)

[http://homepages.laas.fr/mkilliji/docs/journals/jcss.pdf](http://homepages.laas.fr/mkilliji/docs/journals/jcss.pdf)

[http://www.cl.cam.ac.uk/~ks640/files/papers/wpes2014.pdf](http://www.cl.cam.ac.uk/~ks640/files/papers/wpes2014.pdf)

etc.

There are only 9 billion humans. Therefore to identify one, you only need 34
bits! Extracting the right 34 bit of information from the petabytes available
each second, while requiring some mathematical and computing resources, is
clearly not impossible.

Beware also of the Air Force 1 effect: when the American secret services
destroyed the World Trade Center, they issued an order to ground all
airplanes. All, but one, Air Force One. And therefore everybody knew where it
was, because it was the only plane in the sky keeping signaling meteorological
data.

Similarly, when everybody is tracked on facebook, on ApplePay and on bitcoin
(however anonymously), getting outside of those tracking system only serves to
flag and identify your even better!

We're certainly very close to have a system like in Minority Report, where not
only real-time tracking of everybody will be relatively easy, but of course,
probabilistic prevision of (near) future behavior will be possible as well.

When you can track with a high resolution spy satellite or drone somebody in
downtown Los Angeles at 11:43, you can predict with quite a certainty that he
won't be in New York at 11:50. Given physical constraints and Bayes
statistics, you can predict quite a lot.

[http://www.dailymail.co.uk/sciencetech/article-2269563/The-U...](http://www.dailymail.co.uk/sciencetech/article-2269563/The-
U-S-militarys-real-time-Google-Street-View-Airborne-spy-camera-track-entire-
city-1-800MP.html)

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echolima
Getting ready for Nanowrimo tomorrow? :)

