[Bitcoin-development] Feedback request: colored coins protocol

[Bitcoin-development] Feedback request: colored coins protocol

[Flavien Charlon]

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Hi,

I am the lead developer of Coinprism <https://www.coinprism.com/>, the new
colored coins web wallet. After some discussions with the other people
involved with colored coins, I wrote a specification document describing
the colored coins protocol that we are using in coinprism.

I am looking for feedback/discussions regarding the protocol before we move
from TestNet to MainNet. The document is here:
https://github.com/Flavien/colored-coins-protocol/blob/master/specification.mediawiki
.

The colored coin protocol is layered on top of the existing Bitcoin
protocol and requires no modification of the existing protocol, so it can
be used today. This means that SPV is not as efficient, as the client needs
to backtrack up to the issuing transaction to find the color of an output,
but that is something we can live with.


The protocol marks transactions either as issuance or transfer transactions
by using an OP_RETURN output with a 9 bytes marker. The protocol uses the
value of an output as the colored value. So if an output has 1 BTC and is
colored with color A, that means we have 1 BTC colored with color A.

An alternative would have been to completely disconnect the colored value
and the real BTC value. The colored value of each output would be encoded
in an OP_RETURN output. Someone who wants to send 1000 colored coins would
craft a transaction with an output with the smallest possible amount of BTC
(5,400 satoshis) and indicate in the OP_RETURN that they are sending 1000
colored coins.
The two reasons why we haven't chosen that approach is that first, this
only works with a limited number of outputs given that we have only 40
bytes. And second, this could lead to people spamming the network with very
small outputs (but containing an arbitrary number of colored coins).

On the other hand, with the approach we're using (colored value = actual
value of the output), the 5,400 satoshis rule means that the smallest unit
of colored coin you can send is 5,400 satoshis.

If you want to issue 1 million shares, while still being able to trade each
share individually, you'd have to set 1 share = 5,400 satoshis, and you
would need a capital of 54 BTC for issuing a million shares. It's not a big
problem in itself, but still a slight inconvenience.

Do you think this is the right approach?

Feel free to reply with any feedback regarding the protocol.

Thanks,
Flavien

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Re: [Bitcoin-development] Feedback request: colored coins protocol

[Mark Friedenbach]

On 04/06/2014 01:59 PM, Flavien Charlon wrote:
> Do you think this is the right approach?

No, I'm afraid it has significant flaws. The two chief flaws are (1)
there is absolutely no reason to include asset tagging information if it
is not validated - that just bloats the block chain, and (2) you
shouldn't be using fixed increments for share sizes either. It's not
future-proof as the minimum output size changes based on the minimum fee
(currently 540 satoshis, not 5,400, and it will float in the near
future). And needing a capital of 54 btc for a million shares is totally
unacceptable.

Flavien, I know that I've seen you on the Bitcoin-X mailing list, where
these issues have been mostly worked out:

https://groups.google.com/forum/#!forum/bitcoinx

Have you seen the padded order-based coloring scheme worked out here?

https://github.com/bitcoinx/colored-coin-tools/wiki/colored_coins_intro

Kind regards,
Mark Friedenbach

Re: [Bitcoin-development] Feedback request: colored coins protocol

[Flavien Charlon]

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Thanks for the feedback Mark.

> (1) there is absolutely no reason to include asset tagging information if
it is not validated

Sure, there is a good reason to include it in the blockchain: so that
clients don't need external information to recognize colored coins. Also,
I'm not sure what you mean by "not validated", in that proposal, the tagged
transaction is the authoritative source of information.

> that just bloats the block chain

9 bytes is much less than what Mastercoin and counterparty are doing
(certainly under the 40 bytes allowed).

> Have you seen the padded order-based coloring scheme worked out here?

Yes I have seen it and find the padding quite clumsy and unintuitive. A
more general solution is the one I described in my original post, where the
color value is entirely separate from the satoshi value, and encoded
separately: if you have to have an additional "padding" value to calculate
color_value = satoshi_value - padding, you might as well have color_value
directly, independently from satoshi_value. But I don't even think it is
necessary:

> (2) And needing a capital of 54 btc for a million shares is totally
unacceptable.

An easy workaround is to have various scales, the same way you have $1
bills, $5 bills an $10 bills. I don't see that as a big problem. That way
the protocol is more lightweight and simple.

Also those 54 BTC (actually 5.4 BTC if the dust is now 540 satoshis) become
part of the capital of the company, and can always be recovered by
uncoloring the shares. It's an investment, not an expense, so I think it is
acceptable.

Best,
Flavien






On Mon, Apr 7, 2014 at 12:23 AM, Mark Friedenbach <mark@monetize.io> wrote:

> On 04/06/2014 01:59 PM, Flavien Charlon wrote:
> > Do you think this is the right approach?
>
> No, I'm afraid it has significant flaws. The two chief flaws are (1)
> there is absolutely no reason to include asset tagging information if it
> is not validated - that just bloats the block chain, and (2) you
> shouldn't be using fixed increments for share sizes either. It's not
> future-proof as the minimum output size changes based on the minimum fee
> (currently 540 satoshis, not 5,400, and it will float in the near
> future). And needing a capital of 54 btc for a million shares is totally
> unacceptable.
>
> Flavien, I know that I've seen you on the Bitcoin-X mailing list, where
> these issues have been mostly worked out:
>
> https://groups.google.com/forum/#!forum/bitcoinx
>
> Have you seen the padded order-based coloring scheme worked out here?
>
> https://github.com/bitcoinx/colored-coin-tools/wiki/colored_coins_intro
>
> Kind regards,
> Mark Friedenbach
>
>
> ------------------------------------------------------------------------------
> _______________________________________________
> Bitcoin-development mailing list
> Bitcoin-development@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>

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Re: [Bitcoin-development] Feedback request: colored coins protocol

[Jorge Timón]

On 4/7/14, Flavien Charlon <flavien.charlon@coinprism.com> wrote:
> Also those 54 BTC (actually 5.4 BTC if the dust is now 540 satoshis) become
> part of the capital of the company, and can always be recovered by
> uncoloring the shares. It's an investment, not an expense, so I think it is
> acceptable.

This doesn't make much sense to me.
If you print shares on gold plates instead of paper, is that gold
"part of the capital of the company"? I don't think so.

Re: [Bitcoin-development] Feedback request: colored coins protocol

[Flavien Charlon]

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Jorge, they'd have to be. Otherwise, assuming the price of the share goes
low enough, you could buy a share of the company, melt the gold plate, and
sell it for a profit. If the gold is part of the capital of the company,
the cheapest a share can be is the price of the gold on which the stock
certificate is printed.

This is why I think the importance of padding with colored coins is
overblown.


On Mon, Apr 7, 2014 at 1:12 PM, Jorge Timón <jtimon@monetize.io> wrote:

> On 4/7/14, Flavien Charlon <flavien.charlon@coinprism.com> wrote:
> > Also those 54 BTC (actually 5.4 BTC if the dust is now 540 satoshis)
> become
> > part of the capital of the company, and can always be recovered by
> > uncoloring the shares. It's an investment, not an expense, so I think it
> is
> > acceptable.
>
> This doesn't make much sense to me.
> If you print shares on gold plates instead of paper, is that gold
> "part of the capital of the company"? I don't think so.
>

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Re: [Bitcoin-development] Feedback request: colored coins protocol

[Mark Friedenbach]

Flavien, capital is wealth or resources available for the stated purpose
of the company. These bitcoins represent nothing more than a speculative
floor owned by the investors, not the company.

On 04/07/2014 07:00 AM, Flavien Charlon wrote:
> Jorge, they'd have to be. Otherwise, assuming the price of the share
> goes low enough, you could buy a share of the company, melt the gold
> plate, and sell it for a profit. If the gold is part of the capital of
> the company, the cheapest a share can be is the price of the gold on
> which the stock certificate is printed.
> 
> This is why I think the importance of padding with colored coins is
> overblown.
> 
> 
> On Mon, Apr 7, 2014 at 1:12 PM, Jorge Timón <jtimon@monetize.io
> <mailto:jtimon@monetize.io>> wrote:
> 
>     On 4/7/14, Flavien Charlon <flavien.charlon@coinprism.com
>     <mailto:flavien.charlon@coinprism.com>> wrote:
>     > Also those 54 BTC (actually 5.4 BTC if the dust is now 540
>     satoshis) become
>     > part of the capital of the company, and can always be recovered by
>     > uncoloring the shares. It's an investment, not an expense, so I
>     think it is
>     > acceptable.
> 
>     This doesn't make much sense to me.
>     If you print shares on gold plates instead of paper, is that gold
>     "part of the capital of the company"? I don't think so.
> 
> 

Re: [Bitcoin-development] Feedback request: colored coins protocol

[Flavien Charlon]

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Ok, I guess I'm not using the proper terminology. It would be listed on the
"Asset" section of the company's balance sheet, is what I meant.


On Mon, Apr 7, 2014 at 4:06 PM, Mark Friedenbach <mark@monetize.io> wrote:

> Flavien, capital is wealth or resources available for the stated purpose
> of the company. These bitcoins represent nothing more than a speculative
> floor owned by the investors, not the company.
>
> On 04/07/2014 07:00 AM, Flavien Charlon wrote:
> > Jorge, they'd have to be. Otherwise, assuming the price of the share
> > goes low enough, you could buy a share of the company, melt the gold
> > plate, and sell it for a profit. If the gold is part of the capital of
> > the company, the cheapest a share can be is the price of the gold on
> > which the stock certificate is printed.
> >
> > This is why I think the importance of padding with colored coins is
> > overblown.
> >
> >
> > On Mon, Apr 7, 2014 at 1:12 PM, Jorge Timón <jtimon@monetize.io
> > <mailto:jtimon@monetize.io>> wrote:
> >
> >     On 4/7/14, Flavien Charlon <flavien.charlon@coinprism.com
> >     <mailto:flavien.charlon@coinprism.com>> wrote:
> >     > Also those 54 BTC (actually 5.4 BTC if the dust is now 540
> >     satoshis) become
> >     > part of the capital of the company, and can always be recovered by
> >     > uncoloring the shares. It's an investment, not an expense, so I
> >     think it is
> >     > acceptable.
> >
> >     This doesn't make much sense to me.
> >     If you print shares on gold plates instead of paper, is that gold
> >     "part of the capital of the company"? I don't think so.
> >
> >
>

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Re: [Bitcoin-development] Feedback request: colored coins protocol

[Jorge Timón]

On 4/7/14, Flavien Charlon <flavien.charlon@coinprism.com> wrote:
> Ok, I guess I'm not using the proper terminology. It would be listed on the
> "Asset" section of the company's balance sheet, is what I meant.

No, it's an asset for the owner of the share, not the company, just
like the gold plates are not assets for the company when someone else
holds them.
What you're doing is getting less capital for the company due to the
money that is going to pay the gold costs.
Are you rising capital or selling gold?
It doesn't make sense to do both at once.
You need money, why would you spend money on gold before asking for
other people's money to build your company?
Investors will appreciate the convenience of being able to buy shares
of your company and gold separately (or not buy gold at all).

It may even be more clear for other use cases different than stocks.
Does an IOU written in a gold plate make sense to you?

Re: [Bitcoin-development] Feedback request: colored coins protocol

[Flavien Charlon]

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An IOU written in a gold plate sure makes no sense. I see what you are
saying, the inconvenience comes from the fact that the buyer has to buy
some amount of BTC at the same time as he buys a share.

That's why I was making the point that you could have a colored coin
representing a single share, a different colored coin representing 10
shares, and another one representing 100 shares (like the different
denominations of dollar bills). Assuming you have a proper application
layer/UI that can hide this from the user, the need for padding is greatly
reduced. My opinion is that the protocol should do the minimum required and
remain as simple as possible. If a proper UI can work around this, then it
might not be worth complicating the protocol for this. Also, the dust rule
may disappear all together one day (it's already been slashed heavily to
540 satoshis), at which point we'll be left with a useless padding
parameter. It's easier to add something when you need it than to remove it.

But I am posting here to see how people feel about this, and I see you are
on the opinion that satoshi_value and color_value should have a degree of
freedom between each other. Thanks for the feedback.


On Mon, Apr 7, 2014 at 7:23 PM, Jorge Timón <jtimon@monetize.io> wrote:

> On 4/7/14, Flavien Charlon <flavien.charlon@coinprism.com> wrote:
> > Ok, I guess I'm not using the proper terminology. It would be listed on
> the
> > "Asset" section of the company's balance sheet, is what I meant.
>
> No, it's an asset for the owner of the share, not the company, just
> like the gold plates are not assets for the company when someone else
> holds them.
> What you're doing is getting less capital for the company due to the
> money that is going to pay the gold costs.
> Are you rising capital or selling gold?
> It doesn't make sense to do both at once.
> You need money, why would you spend money on gold before asking for
> other people's money to build your company?
> Investors will appreciate the convenience of being able to buy shares
> of your company and gold separately (or not buy gold at all).
>
> It may even be more clear for other use cases different than stocks.
> Does an IOU written in a gold plate make sense to you?
>

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Re: [Bitcoin-development] Feedback request: colored coins protocol

[Alex Mizrahi]

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This is beyond ridiculous...

Color kernel which works with padding is still quite simple. I think we
have extra 10-50 lines of code to handle padding in coloredcoinlib.
Essentially we have a couple of lines like this :

    value_wop = tx.outputs[oi].value - padding

(value_wop means "value without padding").
And then we have like 10 lines of code which selects padding for a
transaction.

That's not a lot of extra complexity. And it solves the problem once and
for all.

What you propose instead: "a different colored coin representing 10 shares,
and another one representing 100 shares (like the different denominations
of dollar bills)"  is much more complex, and it won't work:

Suppose you have $100 coin, as a single coin.
How do you send $54.23?
That's simply impossible.

So you'd rather push complexity to higher levels (and create inconvenience
for end users, as you admitted yourself) than add 10-50 lines of code to
color kernel?
I just do not understand this.

But I'm not going to argue. I already wrote everything which I could write
on this topic.

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Re: [Bitcoin-development] Feedback request: colored coins protocol

[Flavien Charlon]

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Thanks for the valuable feedback. I see there is a strong concern with
requiring a large BTC capital for issuing coloring coins, so I am now in
the process of modifying the specification to address that. I will post an
update when this is finished.

By the way, padding doesn't solve the issue entirely (issuing 10 billion
shares sill takes you 100 BTC, even with padding and 1 satoshi = 1 share),
so I am going for the solution where the asset quantity of every output is
explicitly encoded in the OP_RETURN output. That way, whether you are
issuing 1 share or 100 trillions, you never need to pay more than 540
satoshis.


On Mon, Apr 7, 2014 at 8:58 PM, Alex Mizrahi <alex.mizrahi@gmail.com> wrote:

> This is beyond ridiculous...
>
> Color kernel which works with padding is still quite simple. I think we
> have extra 10-50 lines of code to handle padding in coloredcoinlib.
> Essentially we have a couple of lines like this :
>
>     value_wop = tx.outputs[oi].value - padding
>
> (value_wop means "value without padding").
> And then we have like 10 lines of code which selects padding for a
> transaction.
>
> That's not a lot of extra complexity. And it solves the problem once and
> for all.
>
> What you propose instead: "a different colored coin representing 10
> shares, and another one representing 100 shares (like the different
> denominations of dollar bills)"  is much more complex, and it won't work:
>
> Suppose you have $100 coin, as a single coin.
> How do you send $54.23?
> That's simply impossible.
>
> So you'd rather push complexity to higher levels (and create inconvenience
> for end users, as you admitted yourself) than add 10-50 lines of code to
> color kernel?
> I just do not understand this.
>
> But I'm not going to argue. I already wrote everything which I could write
> on this topic.
>
>
>
> ------------------------------------------------------------------------------
> Put Bad Developers to Shame
> Dominate Development with Jenkins Continuous Integration
> Continuously Automate Build, Test & Deployment
> Start a new project now. Try Jenkins in the cloud.
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>
>

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Re: [Bitcoin-development] Feedback request: colored coins protocol

[Jean-Pierre Rupp]

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By deciding to use a decentralized network to hold your assets, it may
make more sense to emit less shares. Two billion shares backed by
coloured coins makes less sense than a more conservative number, like
10,000. That costs a negligible amount of money, at least until the day
when Bitcoin takes over the world and a satoshi becomes very expensive.
But it is irrelevant now.

If you have already created a massive amount of shares for your company,
then the only reasonable solution is for a coloured coin to represent a
bundle of shares as Flavien suggested. Some shareholder could emit
another coloured coin instrument with a genesis block based on a smaller
set of shares to trade among smaller investors unwilling to deal in
terms of the bundled shares.

We need to understand that coloured coins provide benefits, but also has
constraints that are not difficult to live with.

On 10/04/14 13:19, Flavien Charlon wrote:
> By the way, padding doesn't solve the issue entirely (issuing 10 billion
> shares sill takes you 100 BTC, even with padding and 1 satoshi = 1
> share), so I am going for the solution where the asset quantity of every
> output is explicitly encoded in the OP_RETURN output. That way, whether
> you are issuing 1 share or 100 trillions, you never need to pay more
> than 540 satoshis.

-- 
haskoin.com

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Re: [Bitcoin-development] Feedback request: colored coins protocol

[Mark Friedenbach]

On 04/10/2014 05:19 AM, Flavien Charlon wrote:
> By the way, padding doesn't solve the issue entirely (issuing 10 billion
> shares sill takes you 100 BTC, even with padding and 1 satoshi = 1
> share), so I am going for the solution where the asset quantity of every
> output is explicitly encoded in the OP_RETURN output. That way, whether
> you are issuing 1 share or 100 trillions, you never need to pay more
> than 540 satoshis.

At this point, I don't think what you are doing is even colored coins
anymore. You might want to look into Counterparty or Mastercoin.

Re: [Bitcoin-development] Feedback request: colored coins protocol

[Alex Mizrahi]

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> At this point, I don't think what you are doing is even colored coins
> anymore. You might want to look into Counterparty or Mastercoin.
>

Nope, it's still colored coins. The difference between colored coin model
and Mastercoin model is that colored coins are linked to transaction
outputs, while Mastercoin has a notion of address balances.

The implications of this is that in colored coin model explicit
dependencies allow us to rely on SPV. (Assuming that one can fetch the
dependency graph to link txout in question to genesis.)
While it is not the case with Mastercoin.

While it's pretty far from the original colored coins model, what Flavien
have described is identical to it in majority of aspects.

This is an interesting approach, but OP_RETURN size limitations can be a
significant problem for some kinds of applications.

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Re: [Bitcoin-development] Feedback request: colored coins protocol

[Flavien Charlon]

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I have updated the
spec<https://github.com/Flavien/colored-coins-protocol/blob/master/specification.mediawiki>
.

> This is an interesting approach, but OP_RETURN size limitations can be a
significant problem for some kinds of applications.

This is correct, the number of colored outputs you can have per transaction
is limited by OP_RETURN's 40 bytes. We use a compact format
(LEB128<http://en.wikipedia.org/wiki/LEB128>)
for the asset quantity of each output to mitigate that. Assuming you're
transferring small amounts of colored coins, you could have up to about 30
colored ouputs.

It should work for a decentralized exchange (you only really need 2 or 3
colored outputs). Applications like sending dividends in colored coins
however may require splitting into several smaller transactions, but I
believe that's an acceptable limitation.


On Thu, Apr 10, 2014 at 6:24 PM, Alex Mizrahi <alex.mizrahi@gmail.com>wrote:

>
>
>>  At this point, I don't think what you are doing is even colored coins
>> anymore. You might want to look into Counterparty or Mastercoin.
>>
>
> Nope, it's still colored coins. The difference between colored coin model
> and Mastercoin model is that colored coins are linked to transaction
> outputs, while Mastercoin has a notion of address balances.
>
> The implications of this is that in colored coin model explicit
> dependencies allow us to rely on SPV. (Assuming that one can fetch the
> dependency graph to link txout in question to genesis.)
> While it is not the case with Mastercoin.
>
> While it's pretty far from the original colored coins model, what Flavien
> have described is identical to it in majority of aspects.
>
> This is an interesting approach, but OP_RETURN size limitations can be a
> significant problem for some kinds of applications.
>
>
> ------------------------------------------------------------------------------
> Put Bad Developers to Shame
> Dominate Development with Jenkins Continuous Integration
> Continuously Automate Build, Test & Deployment
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>
>

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Re: [Bitcoin-development] Feedback request: colored coins protocol

[Alex Mizrahi]

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>
> Have you seen the padded order-based coloring scheme worked out here?
>
> https://github.com/bitcoinx/colored-coin-tools/wiki/colored_coins_intro


Just to clarify, a variant of padded order-based coloring called epobc is
already implemented in coloredcoinlib (which is used by
ngcccbase/ChromaWallet). It isn't document yet, however.
The idea is to use the otherwise unused nSequence field of first input to
specify padding and differentiate between genesis and transfer transactions.
Padding can be chosen for each transaction individually and can be set to
zero.

Python code is here (I recommend waiting for documentation, though):

https://github.com/bitcoinx/ngcccbase/blob/master/coloredcoinlib/colordef.py#L262

It is able to work with transactions with multiple colored and uncolored
outputs, particularly, p2ptrade transactions.

Examples of p2ptrade transactions on mainnet:
https://blockchain.info/tx/8c1926f2e3527153bf06e8ab2c8a417aad3d8e6cd993a4350efbb4050ab961fa
https://blockchain.info/tx/f85b6213939c9cbc14538dd24838061179cac2485f50be20a974b819a85e5ee9(It
looks quite a bit weird, I know.)

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