Bitcoin Forum

how can we help? what do you need?

Basically, ideas what the specific goals of CCT are regarding NXT.

Schedule:
0) new thread for this

1) define an API
 - heavily use case dependent
 - you should contribute what you want to achieve with cross-chain trading
 - price negotiations?

2) design questions
 - I fear we need something like a plugin architecture as transactions of different cryptocurrencies can look completely different
 - re-use of current AE infrastructure?
 - re-use of AT infrastructure?

3) implementation and test

5) deploy

well,attractive.

Here is my proposal on using AE for trading one crypto to another:

Let us assume that we have a NXT asset that corresponds to all the cryptos, eg. BTC, DOGE, AUR, etc. The following example will work with any pair, but for clarity, lets pick BTC and AUR. People who had BTC would be able to do a 1:1 swap for BTCAUR and people who had AUR would be able to do a 1:1 swap for AURBTC. The reverse is possible, these are just trading pairs that lets us use the NXT AE for people to trade. We definitely will need more decimal places in the prices, but the biggest change is that these "swap" assets need to be denominated in one of the cryptos and it usually wont be NXT.

The orderbook would be bids for AURBTC and the asks would be inverse of BTCAUR. This is exactly like forex trading pairs. The market settles on which currency the market is traded in and for crypto when BTC is involved, it is the one that the prices are in. So when a trade is done, here comes the required NXTcore changes!, instead of exchanging the asset for NXT, the asset is exchanged for the agreed amount of the underlying currency, in this case BTC.

The owner of AUR swaps for AURBTC, agrees to trade at 0.1 BTC and gets BTC asset, the other party gets the AURBTC, which is freely convertible to AUR.

I just realized that if we can make change to the NXT API for asset trading to specify the trading to be in units of an asset,then we dont have to bother with all the AURBTC 1:1 swaps! We just directly trade AUR assets for BTC assets and specify that the trade is denominated in BTC. With one simple change to NXT AE handling in the NXT core, we get to use NXT AE for trading any crypto against any crypto that the gateway supports.

This isnt exactly automatic cross chain, but I think it will be what people will want to do, namely trade cryptos. Just one change in NXT API and we can do this as soon as NXT core supports fractions!!

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Now let us say that Mr 47...88 is not satisfied with the above and wants a solution without any gateway involved. In that case we wont have assurance that either party actually has what they say they want to trade, since presumably they are wanting to trade directly from their wallets. It also requires making a crypto to crypto exchange GUI and an interface that prompts the users to locally sign their transactions. Since each transaction would need manual intervention by both parties to complete, I would think that its use would be limited to large transactions only.

I think having the gateways provide an abstracted (and peer reviewed) interface to the external blockchains would allow an AT to manage the transaction process. Something has to interface with the bitcoind and it cant be the AT directly, so I am having trouble seeing how it is possible to do automated cross chain in a totally decentralized way.

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Unless I hear otherwise, I will assume that Mr 47...88 wants NXT to be able to trade crypto to crypto within NXT. My top solution does that and actually has several advantages over a pure cross chain solution, eg. funds are verified and no need to invoke lengthy blockchain transactions for each trade. I will proceed on the assumption that this is acceptable and that we will be able to make the one change in the NXT API.

James

Hey, guys!! I have posted here 'cause it's the current thread:

Mt. Barker Computers and Electronics in Western Australia is now accepting Nxt 'over the counter' for purchases.

We are 'indiamikezulu' (indiamikezulu dot com dot au), a hobby business devoted really to across-the-board cryptocurrency development in Australia rather than any particular crypto -- but we recognised the excellence of Nxt early on, hold coin, and are developing it 'on the ground.'

Actually, MBCE (my business partner's day job) is probably the only place in Australia that accepts more than two cryptos -- we're taking four.

Mark Blair (04 399 58791)

Hea guys - I'd like to be on board with this too. I am getting my client finished, and then there will be a dedicated thing for this.

Current status on the AE client is that I have moved the server requests to POST and also included the latest three new api calls. The one thing that is making trouble is using https and POST - this means that I can't use web-wallets yet. But it occurred to me that that is a rather special case, and for using the AE you rather wnat to run YOUR nxt on your local node, so this can wait.

I have also created a proper QAbstractTableModel for display in table widgets. This was tough, but I have one now, and I can just replicate it for all OB tables. Will be a bit of work, but not serious.

So - AE client will be available soon!

James - sorry that I haven't had time to run dogecoind yet - but I'll catch up..

best,
l8orre

hi very nice!

do you have a link?

Atomic crosschain is by definition NXT blockchain <-> BTC blockchain (or other pair).
It is not NXT blockchain <-> NXT AE <-> BTC blockchain.
If the first is impossible, please give the proof.

I agree.

I am still not available right now. But I think in 3 hours.

Please continue collecting ideas and use cases.

Well, that was quick! I'm amazed at how many Aussies are jumping on board the cyber train. You guys put us stodgy Canucks to shame  ;D

But wouldn't it be better for NXT that everythig goes through AE as hub...?

Welcome. :) Great. I see there is much support for CCT.

Post your ideas regarding CCT here.

Alright, I would focus on this very use case first as 'NXT blockchain <-> NXT AE <-> BTC blockchain' might be very complex both in implementation and understanding. So would make this delicate feature very error-prone.

Let's if we can find a way to do the pair 'NXT <-> BTC' first. Generalization should be easy when considering BTC as a replaceable asset.

That might be true for the pricing issue. That is the data-structures and API calls for placing/cancelling orders could be re-used:

http://wiki.nxtcrypto.org/wiki/Nxt_API#Asset_exchange_operations

One thing that needs more consideration is the asset one could trade in case of CCT.

We would need two different types of assets: onchain-assets and offchain-assets.

Furthermore, offchain-assets need to be bound to certain code in NXT that allows trading with the specified asset. I.e., if a node wants to create a bitcoin transaction, code for creating such transaction is necessary. So is for every additional cryptocurrency as transaction formats and API of the regarding networks can differ.

All AE API calls would need to act according to the specified asset type. Is there a flaw in my logic?

It might be better for Nxt holders, but this is about doing a first, xchain tx.

Maybe, we need to clarify something:

There is no such thing as a crosschain transaction. This is crosschain trading.

I need to leave now for an three hour or so. So, I will leave with more material to discuss:

Introductory:
https://bitcointalk.org/index.php?topic=345619.msg5462784#msg5462784

More detailed:
https://en.bitcoin.it/wiki/Atomic_cross-chain_trading


The basic idea goes as follows (publish = submit to the network):

1) Alice and Bob exchange unready transactions.

-> If Alice publishes a transaction, Alice will reveal a secret that Bob needs to publish his transaction

3) Alice publishes her transaction.
4) Bob can publish as well now.

Yes, good to clarify that.  Would this be a good time to explore Nxt parallel block chain for this application?

This sounds like an autonomous contract to me. Whence a contract is established, as long as the parties in the contract do what they are supposed to do the contract will be executed in the order. I guess AT can play a role in it.

Is this relevant at all to the discussion?

CoinWitness: https://bitcointalk.org/index.php?topic=277389.0

Sounds reasonable to me. Fees for executing the contract (we will pay per op) needs to be evenly split between the parties in order to prevent one party loosing more than the other one.

That is really interesting, especially for AT: https://bitcointalk.org/index.php?topic=463731.0
I sent CIYAM Open a PM on that. Thank you very much for that.

For CCT, as it builds upon AT and AE, we need should not need to bother with that as the 'dirty' work is done a layer underneath of us.

Chuck, there are two more posts similar to that one that I think are also relevant -- I am hunting them down.

I'm glad you forwarded that to CIYAM, because that's definitely beyond my pay grade. :)

any other detail??

We also need to discuss how automatic we want to have CCT.

If we want everything (including creating BTC transactions), we somehow need to create them without the users direct intervention. Storing some private keys in the NXT blockchain is not an option.

Yes, agreed,  I would say make it fully automatic

That would be the most convenient option, I know. But how to create a blank transaction without the private key of the user AND without revealing the secret necessary to perform the corresponding transaction on the other blockchain.

We have time to discuss this until AT and AE are up and running.

https://github.com/Coinffeine/coinffeine/wiki/Exchange-algorithm

Highly relevant

Yeah, that's the 3Mil Nxt question right there.   ;)

Unfortunately the CoinWitness thing and SCIP "goes right over my head" so I won't be specifying anything like it with our initial AT.

For the case of atomic cross-chain transactions an AT to do the equivalent of the pair of Bitcoin txs required is actually quite straight forward.

It will require a specific Nxt AT API command to "verify that the SHA256" of a value matches what is expected (this will need to be discussed with CfB).

Anyway after you've signed and returned the Bitcoin refund to the person wanting to buy NXT from you then you publish an AT containing the SHA256 hash the buyer sent you and their account # (for sending to if it proceeds) and giving that AT the agreed amount (so the NXT is under the AT's control).

The guy wanting to purchase NXT then sends the "secret key" as an AM to the AT - the AT will verify that the secret in the message is correct (i.e. when hashed gives the matching value) and then sends its balance to the "NXT buyer".

The NXT seller would then have to fix up the raw transaction by inserting the secret into it and broadcasting it (not quite as easy actually compared to the Nxt side of things) although it should be easy enough to "whip up" a script or small program to help with the Bitcoin side of things.

Any progress on this?

This is from ChuckOne regarding his work on Cross Chain Transactions (CCT), we need input to help develop:

I am waiting for:
 - AE and AT
 - usability/security ideas/suggestions in the CCT thread, i.e. in which want you as a user trade BTC and NXT?

As you might imagine it's not just "click a button and let NXT trade BTC <-> NXT". You need to somehow specify your BTC account, your NXT account. So, do you want to store you bitcoin-wallet in your CCT/NXT client? How much convenience do you as user need/want?

What are the restrictions? Do you want to be online when the transactions are exchanged (remember: we cannot store private data on the blockchain)? How long do you want to be online? Do you have client/node you trust that can be online for you for the time being to refund in case your trading partner scammed you?

Think I figured this one out, it requires that a few forgers all agreeing whether or not a transaction has gone through though, a couple of them can play dirty and it still works.

Already sent it to some of you but anyone who wants to see my algorithm, shoot me a PM and I'll send it to you.  I am a programmer but haven't touched Nxt source code yet and would most likely need help implementing it!

5 million nxt!  isn't that like $25,000,000????  for the person or team that figures this out, it is enough to retire for life!

no. nxt is still just a few cents each.

You mean it's a few cents each until someone figures out this problem? :)

As far as I'm concerned, each nxt is worth about $10

ahhhh, right $250,000.  Still..... that is quite a nice bonus!  I am guessing somebody will get this done. 

The problem is, it hasn't been known whether or not a trustless solution exists.

I've got an idea for one that at least requires multiple trusted accounts ganging up to mess things up.. which may be too much trust.  PM me to find out more if you can help me implement it. Thanks.

anyone worked on this project?

AT needs to be completed.

Is this bounty still active?

Who put up the 3-5M? Was it you pinarello?

I would give this my best shot, and find some others with cryptographic / programming experience to see if this can be done.

My bounty is still active.

Hi,

Glad to hear it.
What is your connection with NXT if you don't mind me asking?
Also, was proof of that much NXT posted somewhere?

I have some ideas how a cross-chain trustless system could be achieved but they are very out-of-the box ideas. I hope this will not be a problem.
If this were simple it'd already be done ;)

Should we be talking about this on nxtforum? There are some users there that may want to help contribute to solving this challenge.

Cheers,
- Fractal

http://www.nxtexplorer.com/nxt/nxt.cgi?action=3000&acc=4747512364439223888
His name is the first four and last three digits of his Nxt account number. At some point he posted token to prove ownership. (You can look up his post.)

nxtforum would be a better idea imho

Thanks for the info!

Figured it must be a founder (assuming it's all legit)

I think we should move this discussion to somewhere on nxtforum and see what other people have the interest (and ability)

I am thinking a large project like this would probably take more than one dev. Two might work.
I mean, really, this feature is the Holy Grail of crypto.  ;D

I would want to know who I'd be working with and to speak with whoever is putting up the NXT. The problem with doing such a big bounty like this is there is really nothing keeping the poster honest at the end of the day... It's a big leap of faith for a long project.

I would chat with ChuckOne (https://nxtforum.org/index.php?action=profile;u=140), he seems to be willing and able to work on this project and showed a lot of interest.  I can assure you the bounty is real and legitimate, and would probably be placed in the care of Anon (escrow) once there was some commitment. 

Thanks for the reassurance, some escrow would give me faith in the bounty.

I'll see if ChuckOne is interested.

Is this idea already transformed to http://multigateway.org/  or is this conversation still active?

Multigateway is not x-chain transactions, it's a hosted server that converts BTC to a Nxt Asset, not fully trustless.  However, Nxt is nearing release of Smart Contracts which will enable trustless x-chain transactions.