<p>Perhaps I missing something obvious about the definition of coloured coins, but this appears to be very simple. Just create a transaction that transfers 300 coins and have an unsigned input connected to the coloured output. send to the owner of the coloured output, they sign it and broadcast.</p>
<div class="gmail_quote">On Sep 22, 2012 11:10 AM, "Jorge Timón" <<a href="mailto:timon.elviejo@gmail.com">timon.elviejo@gmail.com</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
I'm very interested in this. I was expecting transitive/multi-hop<br>
transactions (Ripple) with colored coins, and I don't understand why<br>
is not possible.<br>
<br>
>From <a href="https://en.bitcoin.it/wiki/Contracts" target="_blank">https://en.bitcoin.it/wiki/Contracts</a><br>
<br>
---<br>
SIGHASH_ALL: This is the default. It indicates that everything about<br>
the transaction is signed, except for the input scripts. Signing the<br>
input scripts as well would obviously make it impossible to construct<br>
a transaction, so they are always blanked out. Note, though, that<br>
other properties of the input, like the connected output and sequence<br>
numbers, are signed; it's only the scripts that are not. Intuitively,<br>
it means "I agree to put my money in, if everyone puts their money in<br>
and the outputs are this".<br>
---<br>
<br>
Why "Signing the input scripts as well would obviously make it<br>
impossible to construct a transaction"?<br>
I don't understand that part. I think a new SIGHASH_* type that<br>
doesn't pay attention to that "obviously" is needed to achieve what we<br>
want.<br>
<br>
Say we want the following transaction:<br>
<br>
A 1 satoshi -> B 1 satoshi -> C 100 btc -> A<br>
<br>
It would be necessary to sign the following:<br>
<br>
Inputs: from srcA, from srcB,<br>
Outputs: 1 satoshi to destB, 1 satoshi to destC, 100 btc to destA<br>
<br>
"from srcC" is not really necessary.<br>
<br>
This same scheme can be used for n-hops.<br>
<br>
What am I missing?<br>
<br>
On 9/22/12, Jeff Garzik <<a href="mailto:jgarzik@exmulti.com">jgarzik@exmulti.com</a>> wrote:<br>
> Forum URL: <a href="https://bitcointalk.org/index.php?topic=112007.0" target="_blank">https://bitcointalk.org/index.php?topic=112007.0</a><br>
><br>
> gmaxwell was talking about colored coins[1] in IRC recently. They are<br>
> potentially interesting in the context of distributed bonds[2], which<br>
> I am currently pursuing with pybond[3].<br>
><br>
> Here is the problem I am trying to solve, does the crowd have an answer?<br>
><br>
> 1. Alice transfers a 1-satoshi colored coin to Bob.<br>
> 2. Bob transfers 100 BTC to Alice. May be restricted to 1 txout, if<br>
> that eases implementation details.<br>
> 3. Steps #1 and #2 happen as an atomic unit, all-or-none.<br>
> 4. Alice and Bob must both approve this atomic transfer of coins, with<br>
> appropriate signatures.<br>
><br>
> Is this possible within the current bitcoin system? As far as I can<br>
> see, the answer is "no" but maybe I'm missing something.<br>
><br>
> My best guess to the answer is "possible, but requires a new SIGHASH_*<br>
> type"?<br>
><br>
> [1] <a href="https://bitcointalk.org/index.php?topic=106449.0" target="_blank">https://bitcointalk.org/index.php?topic=106449.0</a><br>
> [2] <a href="https://bitcointalk.org/index.php?topic=92421.0" target="_blank">https://bitcointalk.org/index.php?topic=92421.0</a><br>
> [3] <a href="https://github.com/jgarzik/pybond" target="_blank">https://github.com/jgarzik/pybond</a><br>
><br>
> --<br>
> Jeff Garzik<br>
> exMULTI, Inc.<br>
> <a href="mailto:jgarzik@exmulti.com">jgarzik@exmulti.com</a><br>
><br>
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<br>
<br>
--<br>
Jorge Timón<br>
<br>
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