
Exotic Transaction Types with Bitcoin - enmaku
http://codinginmysleep.com/exotic-transaction-types-with-bitcoin/
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robertskmiles
This is very interesting and I think needs to be more widely known. There is a
general perception of Bitcoin as simply a currency useful to criminals. The
idea that it is capable of useful things that regular currency can't do helps
to legitimise it.

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anologwintermut
Smart property doesn't work unless the control devices speak bitcoin(and are
probably online). Bitcoin, because of its distributed nature, can't keep
secrets, so it is impossible to tie the necessarily secret cryptographic
credentials used for access control to public transactions.

You end up having to give escrow keys to a third party who well they might
agree to be bound by a bitcoin script contract, can't actually be forced to
honor such a script any more than they could with a normal loan/contract.

~~~
enmaku
By way of a functional example:

I have a lock, it knows it has a unique ID of 123.

I have a keypair A, the lock is programmed to trust messages signed by keypair
A.

My friend has a keypair B. I encode a message in the block chain signed by A
that says something equivalent to "lock 123, you may open for whoever controls
public key B"

When either I or my friend come to the door and scan at the lock, we send it
our public key. If the public key matches one that the lock has been told to
trust, it sends back some random data. We sign that random data with private
key A or B, thus proving that we actually own that keypair, and the lock
opens.

If someone else sends a message to lock 123 that isn't signed in an
appropriate way by some key the lock has been told to trust it ignores the
encoded message. If someone sends it a public key that it doesn't trust, it
ignores that too.

I need to give access to my wife, who holds keypair C. I send another message
to the lock saying "allow access for keypair C but also make keypair C an
administrator so she can grant access to others too"

All of this happens transparently in milliseconds with a simple application
that could run on your smartphone.

~~~
anologwintermut
If that works _, it works without bitcoin. I can send that messaged, signed,
with or with out bitcoin. Conversely, no bitcoin script can force me to sign
that message since no bitcoin script can contain that private key. Just
because a systems uses public key crypto , doesn't mean its works with
bitcoin.

_ In the sense that it works securely. It clearly works for giving someone
authorization.

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dfc
The audio of the talk is awful. Are there any better sources for the original
talk?

~~~
enmaku
[http://soundcloud.com/david-perry-17/the-future-of-
bitcoin-n...](http://soundcloud.com/david-perry-17/the-future-of-bitcoin-new)

That's the best I could do - I'm not exactly an audio engineer but I can
remove noise and normalize at least. Not much I can do about the echo, but if
someone else knows a way, downloads are enabled so feel free.

~~~
jaylevitt
It's theoretically possible with deconvolution, but I don't know that anyone's
had much success there without a bunch of MATLAB coding and a perfect impulse
of the room.

There's a newish plugin called Zynaptiq Unveil that claims to do "blind"
reverb removal, that is, without having an impulse response. I haven't tried
it, but there's a demo version:

<http://www.zynaptiq.com/unveil/>

Other interesting conversations about de-reverberation:

<http://comments.gmane.org/gmane.comp.audio.music-dsp/775>
[http://www.gearslutz.com/board/music-
computers/60299-convolu...](http://www.gearslutz.com/board/music-
computers/60299-convolution-reverb-removal.html)

