[C#] 比特幣冒險：掌握BRC-20標準及Witness資料的抽取技巧

2023-12-22

最近幣圈風風火火關於比特幣銘文(Ordinals)，這時候要說到 BRC-20，我相信前幾年如果你有聽過 NFT 或是乙太幣，應該對這名詞覺得有點熟悉但是又陌生

BRC-20 是一個實驗性的比特幣同質化代幣標準，由推特用戶 @domodata 於 2023 年 3 月 8 日基於 Ordinal 協議創建它類似於以太坊的 ERC20 標準，

規定了比特幣上發行代幣的名稱、發行量、轉帳等功能BRC-20 代幣可以通過 Ordinal 協議在比特幣網路上鑄造和轉移

如果您對 BRC-20 代幣等虛擬貨幣感興趣可以看看下面這影片，說的是淺顯易懂

看完之後，簡單的說，就是一群想在比特幣老大哥的鏈上搞事情的人們，至於 NFT 這東西會不會在紅一波我不知道

今天主要就是既然都把銘文寫在鏈上面，我們是不是有辦法透過程式碼，把那張銘文取出

網路上我有找到，講解銘文放置的地方，基本上他就是基於升級後的 Bitcoin 鏈上，一個叫做 Segregated Witness 的地方變大了，可以放到 4M 左右的資料

這邊有相關的資料比特幣、以太坊的一些問題介紹，我就不贅述

至於規格上面要怎麼提取，這邊有不用程式的做法，而且講解的很詳細，我也慢慢的看完且跟著做了一遍去好好理解到底在幹嘛

這影片有興趣也可以看一下，會有點無聊，但是研究技術就是這樣要搞懂都是需要時間

接下來就是如何使用 C# 來提取鏈上面 Witness 中的資料

這邊是我示範用的 TXID : 12d980d930ae49a9aa69d81cf466116259617410bf1c0f89ec1f1ba0c2c3bfc9

1. 我這邊是用 .Net 7 做編譯，首先先安裝套件 NBitcoin , Newtonsoft.Json

2. 之後就是程碼的部份了，這邊我是取用 https://blockchain.info 這網站的資料來調用 Bitcoin 上面的鏈上資料


	using NBitcoin;
	using NBitcoin.DataEncoders;
	using Newtonsoft.Json;
	using System.Net.Http;
	using System.Reflection;
	using System.Text;

	namespace DownloadOrdinalSample
	{
	internal class Program
	{
	public static readonly HttpClient _httpClient = new();



	static void Main(string[] args)
	{
	Console.WriteLine("Hello, Ordinal!");

	var ordinalTxId = "12d980d930ae49a9aa69d81cf466116259617410bf1c0f89ec1f1ba0c2c3bfc9";


	var oData = GetOrdinalData(ordinalTxId);

	File.WriteAllBytes(AppDomain.CurrentDomain.BaseDirectory + "sample.png",oData.Metadata);
	}


	/// <summary>
	/// 取得 TXID 的銘文資料
	/// </summary>
	/// <param name="ordinalTxId"></param>
	/// <returns></returns>
	/// <exception cref="Exception"></exception>
	public static OrdinalData GetOrdinalData(string ordinalTxId)
	{
	using (var request = new HttpRequestMessage())
	{
	request.Method = HttpMethod.Get;

	request.RequestUri = new Uri(string.Format("https://blockchain.info/rawtx/{0}", ordinalTxId));

	try
	{
	using (var response = _httpClient.Send(request))
	{

	var content = response.Content.ReadAsStringAsync().Result;

	if (content != null)
	{
	BlockchainInfoTxModel? json = JsonConvert.DeserializeObject<BlockchainInfoTxModel>(content);
	Input inputs = json?.inputs[0];
	string witness = Convert.ToString(inputs?.witness);

	if (witness == null)
	{
	throw new Exception(string.Format("Error parsing API response from {0}", string.Format("https://blockchain.info/rawtx/", ordinalTxId)));
	}
	OrdinalData ordinal = DecodeWitnessData(ordinalTxId, witness);
	return ordinal;
	}

	return null;
	}
	}
	catch (Exception exp)
	{
	throw new Exception("Error requesting API ", exp);
	}
	}


	}

	/// <summary>
	/// 解析 WitnessData
	/// </summary>
	/// <param name="bitcoinTxId"></param>
	/// <param name="witnessHex"></param>
	/// <returns></returns>
	/// <exception cref="Exception"></exception>
	private static OrdinalData DecodeWitnessData(string bitcoinTxId, string witnessHex)
	{
	BitcoinStream stream = new(Encoders.Hex.DecodeData(witnessHex));

	if (!stream.ProtocolCapabilities.SupportWitness)
	{
	throw new Exception(string.Format("The transaction id {0} is not a witness transaction.", bitcoinTxId));
	}
	WitScript witness = WitScript.Load(stream);

	IEnumerable<byte[]> pushes = witness.Pushes;
	foreach (byte[] push in pushes)
	{
	OrdinalData ordinalData = ParseScriptData(push);
	if (ordinalData != null)
	{
	return ordinalData;
	}
	}
	throw new Exception(string.Format("No ordinal data found in the witness transaction: {0}.", bitcoinTxId));
	}

	private static OrdinalData ParseScriptData(byte[] push)
	{
	Script script = new(push);

	//Debug.WriteLine(script.ToString());

	bool bIsOrdDataRegion = false;
	OrdinalData data = new();

	byte[] arrayMetadata = { };
	foreach (Op op in script.ToOps())
	{ // https://developer.bitcoin.org/reference/transactions.html
	// OP_1 indicates that the next push contains the content type
	// and OP_0 indicates that subsequent data pushes contain the content itself.
	// Multiple data pushes must be used for large inscriptions, as one of taproot's few restrictions is that individual data pushes may not be larger than 520 bytes.

	/*OP_FALSE
	* OP_IF
	* OP_PUSH "ord"
	* OP_1
	* OP_PUSH "text/plain;charset=utf-8"
	* OP_0
	* OP_PUSH "Hello, world!"
	* OP_ENDIF*/
	// https://docs.ordinals.com/inscriptions.html

	/*
	*
	* 2b699194e41d48 OP_IF OP_UNKNOWN(0xed) 6b8c3fec1d7f100325baa82bf0ec3f22ed0aa93b97 e OP_DEPTH OP_UNKNOWN(0xfd) a737b713920eded10ba5 0
	* 117f692257b2331233b5705ce9c682be8719ff1b2b64cbca290bd6faeb54423e [OP_CHECKSIG dfeb9d208701] [OP_DROP 0] [OP_IF 6f7264] [1 696d6167652f706e67] [0 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 805a93d960bb719d8b87a93eb7d2e934058a8bf2b4d2e117e2f6130988e67f18d0350726eee580c6a0f0c841295b28ceee4cce6d74ed9f24111393cc2716eecd23824f0e94435679fa2a100757e333ab89e9e59e4c2e357fb44558acc07c665edea1fce2f971666d1701898ce4c35af88c212a979a3b63117fb19990173c7726e2b711cabee1379b9d685c9469ccbe73b2ff1858448b68112da245b4880dab4feb0262817f6e5c6f0000000049454e44ae426082] OP_ENDIF
	* OP_UNKNOWN(0xc1) 7f692257b2331233b5705ce9c682be8719 OP_UNKNOWN(0xff) 0
	*/
	//Debug.WriteLine(op.ToString());
	//Debug.WriteLine(op.PushData != null ? Encoding.UTF8.GetString(op.PushData).ToString() : "");
	/*if (op.PushData != null && Encoding.UTF8.GetString(op.PushData) == "text/plain;charset=utf-8")
	{

	}*/

	if ((byte)op.Code == 3)
	{
	if (op.PushData == null)
	continue;
	// Convert UTF8 bytes to string
	string pushDataString = Encoding.UTF8.GetString(op.PushData);

	if (pushDataString == "ord")
	{ // specification standard to filter out other junk https://docs.ordinals.com/inscriptions.html
	bIsOrdDataRegion = true; // flag
	}
	//Debug.WriteLine(op.ToString());
	}
	else if ((byte)op.Code == 9 \|\| (byte)op.Code == 24)
	{
	string pushDataString = Encoding.UTF8.GetString(op.PushData);

	data.MetadataType = pushDataString; // set
	}
	else if (op.Code == OpcodeType.OP_PUSHDATA2 && bIsOrdDataRegion)
	{
	if (op.PushData == null)
	continue;

	// combine the old arrayMetadata array with op.PushData
	byte[] newArray = new byte[arrayMetadata.Length + op.PushData.Length];
	Buffer.BlockCopy(arrayMetadata, 0, newArray, 0, arrayMetadata.Length);
	Buffer.BlockCopy(op.PushData, 0, newArray, arrayMetadata.Length, op.PushData.Length);

	arrayMetadata = newArray;
	}
	}
	if (arrayMetadata.Length > 0)
	{
	data.Metadata = arrayMetadata; // set
	return data;
	}

	return null;
	}



	public class OrdinalData
	{
	/// <summary>
	/// text/plain;charset=utf-8
	/// </summary>
	public string MetadataType
	{
	get; set;
	}

	/// <summary>
	/// Hello, world!
	/// </summary>
	public byte[] Metadata
	{
	get; set;
	}
	}


	/// <summary>
	/// 處理 https://blockchain.info 的模型資料
	/// </summary>
	public class Input
	{
	public class PrevOut
	{
	public class SpendingOutpoint
	{
	public int n { get; set; }
	public long tx_index { get; set; }
	}


	public string addr { get; set; }
	public int n { get; set; }
	public string script { get; set; }
	public List<SpendingOutpoint> spending_outpoints { get; set; }
	public bool spent { get; set; }
	public long tx_index { get; set; }
	public int type { get; set; }
	public int value { get; set; }
	}


	public long sequence { get; set; }
	public string witness { get; set; }
	public string script { get; set; }
	public int index { get; set; }
	public PrevOut prev_out { get; set; }
	}


	/// <summary>
	/// 處理 https://blockchain.info 的模型資料
	/// </summary>
	public class BlockchainInfoTxModel
	{
	public class Out
	{
	public int type { get; set; }
	public bool spent { get; set; }
	public int value { get; set; }
	public List<object> spending_outpoints { get; set; }
	public int n { get; set; }
	public object tx_index { get; set; }
	public string script { get; set; }
	public string addr { get; set; }
	}

	public string hash { get; set; }
	public int ver { get; set; }
	public int vin_sz { get; set; }
	public int vout_sz { get; set; }
	public int size { get; set; }
	public int weight { get; set; }
	public int fee { get; set; }
	public string relayed_by { get; set; }
	public int lock_time { get; set; }
	public long tx_index { get; set; }
	public bool double_spend { get; set; }
	public int time { get; set; }
	public uint block_index { get; set; }
	public uint block_height { get; set; }
	public List<Input> inputs { get; set; }
	public List<Out> @out { get; set; }
	}

	}
	}

view raw DownloadOrdinalSample.cs hosted with ❤ by GitHub

之後就會下載到一張這樣的圖片

大概就是這樣吧，基本上我也是改寫，一個網路大大的分享的專案，抽取這部份來用，最近有需要用到，想說就整理一下分享給大家

參考程式碼:

https://github.com/lastbattle/ordinal_inscription.netcore

這範例我放在這有需要的自己取用

https://github.com/donma/DownloadOrdinalSample

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[C#] 比特幣冒險：掌握BRC-20標準及Witness資料的抽取技巧