[Bitcoin-development] UUID to identify chains (payment protocol and elsewhere)

[Bitcoin-development] UUID to identify chains (payment protocol and elsewhere)

[Mark Friedenbach]

At the developer round-table it was asked if the payment protocol would 
alt-chains, and Gavin noted that it has a UTF-8 encoded string 
identifying the network ("main" or "test"). As someone with two 
proposals in the works which also require chain/coin identification (one 
for merged mining, one for colored coins), I am opinionated on this. I 
believe that we need a standard mechanism for identifying chains, and 
one which avoids the trap of maintaining a standard registry of 
string-to-chain mappings.

Any chain can be uniquely identified by its genesis block, 122 random 
bits is more than sufficient for uniquely tagging chains/colored assets, 
and the low-order 16-bytes of the block's hash are effectively random. 
With these facts in mind, I propose that we identify chains by UUID.

So as to remain reasonably compliant with RFC 4122, I recommend that we 
use Version 4 (random) UUIDs, with the random bits extracted from the 
double-SHA256 hash of the genesis block of the chain. (For colored 
coins, the colored coin definition transaction would be used instead, 
but I will address that in a separate proposal and will say just one 
thing about it: adopting this method for identifying chains/coins will 
greatly assist in adopting the payment protocol to colored coins.)

The following Python code illustrates how to construct the chain 
identifier from the serialized genesis block:

     from hashlib import sha256
     from uuid import UUID
     def chain_uuid(serialized_genesis_block):
         h = sha256(serialized_genesis_block).digest()
         h = sha256(h).digest()
         h = h[:16]
         h = ''.join([
             h[:6],
             chr(0x40 | ord(h[6]) & 0x0f),
             h[7],
             chr(0x80 | ord(h[8]) & 0x3f),
             h[9:]
         ])
         return UUID(bytes=h)

And some example chain identifiers:

     mainnet:  UUID('6fe28c0a-b6f1-4372-81a6-a246ae63f74f')
     testnet3: UUID('43497fd7-f826-4571-88f4-a30fd9cec3ae')
     namecoin: UUID('70c7a9f0-a2fb-4d48-a635-a70d5b157c80')

As for encoding the chain identifier, the simplest method is to give 
"network" the "bytes" type, but defining a "UUID" message type is also 
possible. In either case bitcoin mainnet would be the default, so the 
extra 12 bytes (vs: "main" or "test") would only be an issue for 
alt-chains or colored coins.

Kind regards,
Mark Friedenbach

Re: [Bitcoin-development] UUID to identify chains (payment protocol and elsewhere)

[Jeff Garzik]

On Mon, May 20, 2013 at 7:59 PM, Mark Friedenbach <mark@monetize.io> wrote:
> So as to remain reasonably compliant with RFC 4122, I recommend that we
> use Version 4 (random) UUIDs, with the random bits extracted from the
> double-SHA256 hash of the genesis block of the chain. (For colored
> coins, the colored coin definition transaction would be used instead,
> but I will address that in a separate proposal and will say just one
> thing about it: adopting this method for identifying chains/coins will
> greatly assist in adopting the payment protocol to colored coins.)

This proposal seems closer to Version 5 than Version 4, in spirit.
But given that useful content may be deduced from UUID, it is not
truly applicable to either.  A bitcoin-specific version 6, if you
will.


> And some example chain identifiers:
>
>      mainnet:  UUID('6fe28c0a-b6f1-4372-81a6-a246ae63f74f')
>      testnet3: UUID('43497fd7-f826-4571-88f4-a30fd9cec3ae')
>      namecoin: UUID('70c7a9f0-a2fb-4d48-a635-a70d5b157c80')

Note that, as this example unintentionally implies, humans are going
to want a side-by-side mapping /anyway/, just to make it readable and
usable to humans.

Almost all useful multi-chain software will require a readable
shortname string anyway, the thing this proposal wishes to avoid.

-- 
Jeff Garzik
exMULTI, Inc.
jgarzik@exmulti.com

Re: [Bitcoin-development] UUID to identify chains (payment protocol and elsewhere)

[Mike Hearn]

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Bitcoinj already has such chain id's and we use standard Java style reverse
DNS names: org.bitcoin.main, etc. If we want a more global naming system
that seems like a good compromise between uniqueness and readability.
On 20 May 2013 19:45, "Jeff Garzik" <jgarzik@exmulti.com> wrote:

> On Mon, May 20, 2013 at 7:59 PM, Mark Friedenbach <mark@monetize.io>
> wrote:
> > So as to remain reasonably compliant with RFC 4122, I recommend that we
> > use Version 4 (random) UUIDs, with the random bits extracted from the
> > double-SHA256 hash of the genesis block of the chain. (For colored
> > coins, the colored coin definition transaction would be used instead,
> > but I will address that in a separate proposal and will say just one
> > thing about it: adopting this method for identifying chains/coins will
> > greatly assist in adopting the payment protocol to colored coins.)
>
> This proposal seems closer to Version 5 than Version 4, in spirit.
> But given that useful content may be deduced from UUID, it is not
> truly applicable to either.  A bitcoin-specific version 6, if you
> will.
>
>
> > And some example chain identifiers:
> >
> >      mainnet:  UUID('6fe28c0a-b6f1-4372-81a6-a246ae63f74f')
> >      testnet3: UUID('43497fd7-f826-4571-88f4-a30fd9cec3ae')
> >      namecoin: UUID('70c7a9f0-a2fb-4d48-a635-a70d5b157c80')
>
> Note that, as this example unintentionally implies, humans are going
> to want a side-by-side mapping /anyway/, just to make it readable and
> usable to humans.
>
> Almost all useful multi-chain software will require a readable
> shortname string anyway, the thing this proposal wishes to avoid.
>
> --
> Jeff Garzik
> exMULTI, Inc.
> jgarzik@exmulti.com
>
>
> ------------------------------------------------------------------------------
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Re: [Bitcoin-development] UUID to identify chains (payment protocol and elsewhere)

[Mark Friedenbach]

This was meant to go to everyone:

On 5/20/13 7:45 PM, Jeff Garzik wrote:
> On Mon, May 20, 2013 at 7:59 PM, Mark Friedenbach <mark@monetize.io> wrote:
>> So as to remain reasonably compliant with RFC 4122, I recommend that we
>> use Version 4 (random) UUIDs, with the random bits extracted from the
>> double-SHA256 hash of the genesis block of the chain. (For colored
>> coins, the colored coin definition transaction would be used instead,
>> but I will address that in a separate proposal and will say just one
>> thing about it: adopting this method for identifying chains/coins will
>> greatly assist in adopting the payment protocol to colored coins.)
> This proposal seems closer to Version 5 than Version 4, in spirit.
> But given that useful content may be deduced from UUID, it is not
> truly applicable to either.  A bitcoin-specific version 6, if you
> will.
That is true, and perhaps we have enough clout to push an RFC specifying 
a double-SHA256 Version 6, or at least get it reserved. I proposed 
Version 4 (random) because any UUID library should allow you to specify 
the 122 supposedly random bits of that version, whereas conceivably 
there might exist UUID libraries that require a SHA1 pre-image to create 
a Version 5 UUID (I know of no examples though). Regardless, making an 
official double-SHA256 UUID version RFC is an option worth considering.
> And some example chain identifiers:
>
>       mainnet:  UUID('6fe28c0a-b6f1-4372-81a6-a246ae63f74f')
>       testnet3: UUID('43497fd7-f826-4571-88f4-a30fd9cec3ae')
>       namecoin: UUID('70c7a9f0-a2fb-4d48-a635-a70d5b157c80')
> Note that, as this example unintentionally implies, humans are going
> to want a side-by-side mapping /anyway/, just to make it readable and
> usable to humans.
>
> Almost all useful multi-chain software will require a readable
> shortname string anyway, the thing this proposal wishes to avoid.
I think there are perhaps two issues being conflated here (and in Mike's 
response): the UI identifying the network/coin to the user, and the 
matching of the protocol-supplied value to the underlying network/coin 
by the client/daemon. The former necessarily involves manual adjustments 
(e.g, localization), but it's preferable for the latter to be a 
self-validating reference to the block chain. This is a trivial 
difference for multi-chain wallets (what are you doing receiving 
requests for coins in chains you don't know about?), but is important 
for colored coins. Let me explain:

I will be proposing soon a colored coin architecture that allows 
issuance of new coins by anyone for a fee, by means of a special 
category of transaction. The hash of that issuing transaction would then 
be used to generate a UUID identifying the asset for the payment 
protocol and other purposes as well, analogous to how the hash of the 
genesis block identifies the host currency, bitcoin. It is expected that 
there will be many such coins issued, as they can be used to represent 
individual loans or lines of credit. In this context, any colored-coin 
aware client could scan the block chain (or lookup a maintained index) 
to discover the UUID -> coin mapping with absolute certainty. However 
the mechanism for mapping the text "mtgoxUSD" to a specific coin is not 
clear, and using some sort of DNS-resolution system adds huge external 
dependencies. IMHO it is much better to have the identifier derived from 
block chain data directly (and therefore accessible and trusted by all 
nodes), and then carry out optional UI mappings like UUID(...) -> 
"mtgoxUSD" at a higher level.

Does that make sense?

Re: [Bitcoin-development] UUID to identify chains (payment protocol and elsewhere)

[Luke-Jr]

Bitcoin currently uses raw hashes extensively as UUIDs; whether the payment 
protocol should be influence by that or not, I've not given thought to yet.

Some alt coins may share a blockchain, or even merely the genesis block (two 
currently do; despite one of those being a scamcoin, I think the possibility 
should not be dismissed). Because of this, requiring a 1:1 mapping between 
genesis block and chain or coin seems non-ideal.

On Monday, May 20, 2013 11:59:39 PM Mark Friedenbach wrote:
> At the developer round-table it was asked if the payment protocol would
> alt-chains, and Gavin noted that it has a UTF-8 encoded string
> identifying the network ("main" or "test"). As someone with two
> proposals in the works which also require chain/coin identification (one
> for merged mining, one for colored coins), I am opinionated on this. I
> believe that we need a standard mechanism for identifying chains, and
> one which avoids the trap of maintaining a standard registry of
> string-to-chain mappings.
> 
> Any chain can be uniquely identified by its genesis block, 122 random
> bits is more than sufficient for uniquely tagging chains/colored assets,
> and the low-order 16-bytes of the block's hash are effectively random.
> With these facts in mind, I propose that we identify chains by UUID.
> 
> So as to remain reasonably compliant with RFC 4122, I recommend that we
> use Version 4 (random) UUIDs, with the random bits extracted from the
> double-SHA256 hash of the genesis block of the chain. (For colored
> coins, the colored coin definition transaction would be used instead,
> but I will address that in a separate proposal and will say just one
> thing about it: adopting this method for identifying chains/coins will
> greatly assist in adopting the payment protocol to colored coins.)
> 
> The following Python code illustrates how to construct the chain
> identifier from the serialized genesis block:
> 
>      from hashlib import sha256
>      from uuid import UUID
>      def chain_uuid(serialized_genesis_block):
>          h = sha256(serialized_genesis_block).digest()
>          h = sha256(h).digest()
>          h = h[:16]
>          h = ''.join([
>              h[:6],
>              chr(0x40 | ord(h[6]) & 0x0f),
>              h[7],
>              chr(0x80 | ord(h[8]) & 0x3f),
>              h[9:]
>          ])
>          return UUID(bytes=h)
> 
> And some example chain identifiers:
> 
>      mainnet:  UUID('6fe28c0a-b6f1-4372-81a6-a246ae63f74f')
>      testnet3: UUID('43497fd7-f826-4571-88f4-a30fd9cec3ae')
>      namecoin: UUID('70c7a9f0-a2fb-4d48-a635-a70d5b157c80')
> 
> As for encoding the chain identifier, the simplest method is to give
> "network" the "bytes" type, but defining a "UUID" message type is also
> possible. In either case bitcoin mainnet would be the default, so the
> extra 12 bytes (vs: "main" or "test") would only be an issue for
> alt-chains or colored coins.
> 
> Kind regards,
> Mark Friedenbach
> 
> ---------------------------------------------------------------------------
> --- Try New Relic Now & We'll Send You this Cool Shirt
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> that delivers powerful full stack analytics. Optimize and monitor your
> browser, app, & servers with just a few lines of code. Try New Relic
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> _______________________________________________
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> Bitcoin-development@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/bitcoin-development

Re: [Bitcoin-development] UUID to identify chains (payment protocol and elsewhere)

[Melvin Carvalho]

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On 21 May 2013 01:59, Mark Friedenbach <mark@monetize.io> wrote:

> At the developer round-table it was asked if the payment protocol would
> alt-chains, and Gavin noted that it has a UTF-8 encoded string
> identifying the network ("main" or "test"). As someone with two
> proposals in the works which also require chain/coin identification (one
> for merged mining, one for colored coins), I am opinionated on this. I
> believe that we need a standard mechanism for identifying chains, and
> one which avoids the trap of maintaining a standard registry of
> string-to-chain mappings.
>
> Any chain can be uniquely identified by its genesis block, 122 random
> bits is more than sufficient for uniquely tagging chains/colored assets,
> and the low-order 16-bytes of the block's hash are effectively random.
> With these facts in mind, I propose that we identify chains by UUID.
>
> So as to remain reasonably compliant with RFC 4122, I recommend that we
> use Version 4 (random) UUIDs, with the random bits extracted from the
> double-SHA256 hash of the genesis block of the chain. (For colored
> coins, the colored coin definition transaction would be used instead,
> but I will address that in a separate proposal and will say just one
> thing about it: adopting this method for identifying chains/coins will
> greatly assist in adopting the payment protocol to colored coins.)
>
> The following Python code illustrates how to construct the chain
> identifier from the serialized genesis block:
>
>      from hashlib import sha256
>      from uuid import UUID
>      def chain_uuid(serialized_genesis_block):
>          h = sha256(serialized_genesis_block).digest()
>          h = sha256(h).digest()
>          h = h[:16]
>          h = ''.join([
>              h[:6],
>              chr(0x40 | ord(h[6]) & 0x0f),
>              h[7],
>              chr(0x80 | ord(h[8]) & 0x3f),
>              h[9:]
>          ])
>          return UUID(bytes=h)
>
> And some example chain identifiers:
>
>      mainnet:  UUID('6fe28c0a-b6f1-4372-81a6-a246ae63f74f')
>      testnet3: UUID('43497fd7-f826-4571-88f4-a30fd9cec3ae')
>      namecoin: UUID('70c7a9f0-a2fb-4d48-a635-a70d5b157c80')
>
> As for encoding the chain identifier, the simplest method is to give
> "network" the "bytes" type, but defining a "UUID" message type is also
> possible. In either case bitcoin mainnet would be the default, so the
> extra 12 bytes (vs: "main" or "test") would only be an issue for
> alt-chains or colored coins.
>

This is essentially name spacing.  As registries grow namespaces become
more important.  In bitcoin's quest for decentrality there's also the
question of who maintains the registry.

Some out of band algo/hash could work so long as there was a one to one
relationship between the described object and the UUID.  In this case the
gensis block may not uniquely identify a coin.

The normal way to namespace a registry on the internet is to allow it to be
a URI.  In this case an http style uri has the added bonus side effect that
it can be dereferencable and both human and machine readable.  So yes
something like org.bitcoin.* is good, just simply growing things to http
style uris is cleaner, imho


>
> Kind regards,
> Mark Friedenbach
>
>
> ------------------------------------------------------------------------------
> Try New Relic Now & We'll Send You this Cool Shirt
> New Relic is the only SaaS-based application performance monitoring service
> that delivers powerful full stack analytics. Optimize and monitor your
> browser, app, & servers with just a few lines of code. Try New Relic
> and get this awesome Nerd Life shirt! http://p.sf.net/sfu/newrelic_d2d_may
> _______________________________________________
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> Bitcoin-development@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/bitcoin-development
>

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Re: [Bitcoin-development] UUID to identify chains (payment protocol and elsewhere)

[Jeff Garzik]

On Wed, May 22, 2013 at 6:27 AM, Melvin Carvalho
<melvincarvalho@gmail.com> wrote:
> Some out of band algo/hash could work so long as there was a one to one
> relationship between the described object and the UUID.  In this case the
> gensis block may not uniquely identify a coin.

What does this mean?  It seems extremely unlikely that two different
genesis blocks will have the same hash.

-- 
Jeff Garzik
exMULTI, Inc.
jgarzik@exmulti.com

Re: [Bitcoin-development] UUID to identify chains (payment protocol and elsewhere)

[Melvin Carvalho]

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On 22 May 2013 16:07, Jeff Garzik <jgarzik@exmulti.com> wrote:

> On Wed, May 22, 2013 at 6:27 AM, Melvin Carvalho
> <melvincarvalho@gmail.com> wrote:
> > Some out of band algo/hash could work so long as there was a one to one
> > relationship between the described object and the UUID.  In this case the
> > gensis block may not uniquely identify a coin.
>
> What does this mean?  It seems extremely unlikely that two different
> genesis blocks will have the same hash.
>

Two coin ecosystems could have the same genesis block


>
> --
> Jeff Garzik
> exMULTI, Inc.
> jgarzik@exmulti.com
>

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Re: [Bitcoin-development] UUID to identify chains (payment protocol and elsewhere)

[Jeff Garzik]

On Wed, May 22, 2013 at 10:12 AM, Melvin Carvalho
<melvincarvalho@gmail.com> wrote:
> On 22 May 2013 16:07, Jeff Garzik <jgarzik@exmulti.com> wrote:
>>
>> On Wed, May 22, 2013 at 6:27 AM, Melvin Carvalho
>> <melvincarvalho@gmail.com> wrote:
>> > Some out of band algo/hash could work so long as there was a one to one
>> > relationship between the described object and the UUID.  In this case
>> > the
>> > gensis block may not uniquely identify a coin.
>>
>> What does this mean?  It seems extremely unlikely that two different
>> genesis blocks will have the same hash.
>
>
> Two coin ecosystems could have the same genesis block

That has really, really bad side effects.  The whole point of the
bitcoin consensus algorithm is to avoid situations like this.

We don't want to encourage that behavior with code.

-- 
Jeff Garzik
exMULTI, Inc.
jgarzik@exmulti.com

Re: [Bitcoin-development] UUID to identify chains (payment protocol and elsewhere)

[Luke-Jr]

On Wednesday, May 22, 2013 2:20:22 PM Jeff Garzik wrote:
> On Wed, May 22, 2013 at 10:12 AM, Melvin Carvalho
> 
> <melvincarvalho@gmail.com> wrote:
> > On 22 May 2013 16:07, Jeff Garzik <jgarzik@exmulti.com> wrote:
> >> On Wed, May 22, 2013 at 6:27 AM, Melvin Carvalho
> >> 
> >> <melvincarvalho@gmail.com> wrote:
> >> > Some out of band algo/hash could work so long as there was a one to
> >> > one relationship between the described object and the UUID.  In this
> >> > case the
> >> > gensis block may not uniquely identify a coin.
> >> 
> >> What does this mean?  It seems extremely unlikely that two different
> >> genesis blocks will have the same hash.
> > 
> > Two coin ecosystems could have the same genesis block
> 
> That has really, really bad side effects.  The whole point of the
> bitcoin consensus algorithm is to avoid situations like this.
> 
> We don't want to encourage that behavior with code.

In some cases, multiple currencies can use the same blockchain (not just the 
singular genesis block). This use case *is* something we want to encourage - 
no reason for people to make an entirely new blockchain if their altcoin fits 
within the scope of Bitcoin or another existing altchain.

Re: [Bitcoin-development] UUID to identify chains (payment protocol and elsewhere)

[Jeff Garzik]

On Wed, May 22, 2013 at 10:29 AM, Luke-Jr <luke@dashjr.org> wrote:
> In some cases, multiple currencies can use the same blockchain (not just the
> singular genesis block). This use case *is* something we want to encourage -
> no reason for people to make an entirely new blockchain if their altcoin fits
> within the scope of Bitcoin or another existing altchain.

OK, let me qualify.  Layers on top are one thing, but we really do not
want to support cases like the fork that leaves the genesis block
intact, and leaves the subsidy at 50.0 BTC forever.

-- 
Jeff Garzik
exMULTI, Inc.
jgarzik@exmulti.com

Re: [Bitcoin-development] UUID to identify chains (payment protocol and elsewhere)

[Gavin Andresen]

Getting back to the original proposal:

RE: uuid instead of "main" / "test" in the payment protocol:

I vote no.

The payment protocol will become at least 3 BIPs:

1) Protocol messages (current gist, essentially)
2) MIME type
3) bitcoin: URI extension

An alt coin will need its own version of (2) and (3), so when you
click on a foocoin: link a foocoin-specific MIME type is fetched and
foocoin.exe is launched to handle the request.

... or a specific MIME type is fetched and delivered to the
HandlesLotsOfCoins application (... and it knows what MIME type it is
getting, so can Do the Right Thing).

If a payment request is delivered via HTTP or email, it will be
bundled up in an envelope of some sort with the MIME type attached.

So, after further thought, I've changed my mind: which coin would be
encoded in the MIME type.  Which chain for that coin would be encoded
in PaymentDetails.network.

-- 
--
Gavin Andresen
Chief Scientist, Bitcoin Foundation
https://www.bitcoinfoundation.org/