Colored Coin Wallet

[genterrios]

Hello all!

I'm giving a try to the NBitcoin Library on my way to create a colored coin wallet. I have a few questions maybe you can help me.
I'm trying to build a colored coin wallet using NBitcoin and any block explorer. The thing is that I can use any block explorer for almost every functionality of the wallet besides asking for my balance in colored coins. What are the ways to get the balance of an address in colored coins if not using CoinPrism API or QbitNinja?? If I'm not wrong every other block explorer like BlockTrail, Blockchan.info or Blockr do not let me to do that.

Another question is related to the structure and components of a web or hybrid wallet. I recognized the following main components:
* Library for Key Management and Signing (NBitcoin, BitcoinJS, BitcoinJ)
* Block explorer to interact with the network and publish transactions

Is that correct? What other components should I take into account for the development of a colored coin wallet?

Thanks in advance for your help and for the support and dedication for the Bitcoin community!

[Nicolas Dorier]

Hey, when you have questions about NBitcoin, I think posting on github is better, because I will see it more easily.
You can reach me by mail as you finally did, however the info I gave you won't be indexed by search engines. :p

Responses for other people that might find this question :

* Open Asset is not SPV compatible, which mean you need either need to trust third party services or having a full node and scanning the blockchain yourself
* You can ask a proof to third party services for colored coins, the problem is that the proof can be arbitrarily big, especially with OA.
* QBitNinja is a wallet service which support OA, and open source I created.
* The key management and signing must be done by the client with the libraries you mentioned. (QBitNinja can only generate new addresses, but you can do it yourself client side and add to your server wallet)

The public server of qbitnina (http://api.qbit.ninja/) is not meant for production so you would need to host it yourself.
If you don't want to bother, and don't need the wallet feature of qbit ninja, then Coinprism is a better bet.

Since the client can't ask proof to third party server about colored coins, you should cross check the coins you are spending in every new transaction are right with several explorers. (coinprism + qbitninja)

I think chain.com is working on OA also, I have seen some commits on their repo... not sure about it though.

[genterrios]

Thanks for the reply! I do have one more question? I read the colored coin paper and I can't find anything about how the protocol works regarding fraud (falsification of colroed coins) and double spend..I ask this because when you tranfer bitcoin the miners and the network check those things ath the time of block creation. How colored coin protocol do it??

[Nicolas Dorier]

Thanks for the reply! I do have one more question? I read the colored coin paper and I can't find anything about how the protocol works regarding fraud (falsification of colroed coins) and double spend..I ask this because when you tranfer bitcoin the miners and the network check those things ath the time of block creation. How colored coin protocol do it??

A normal coin (normally 600 satoshi) is used to "bear" the color. Miners don't have to know about colored coin, they just validate with consensus rules the coin which bear the color.
As a normal bitcoin, you can trace a colored coin back in time until the moment when it is issued.
The issuance is signed by the issuer. (By spending a special coin I call "IssuanceCoin")
The issuer is represented by the scriptPubKey of the issuance coin, the AssetId is derived from the scriptPubKey of the issuer.

I explain some of that in my book.