Boltcard integration (#5419)

* Boltcard integration

* Add API for boltcard registration

BTCPayServer/Controllers/UIBoltcardController.cs

@@ -0,0 +1,70 @@
+#nullable enable
+using Dapper;
+using System.Linq;
+using System.Security;
+using System.Threading.Tasks;
+using BTCPayServer.Data;
+using BTCPayServer.NTag424;
+using BTCPayServer.Services;
+using LNURL;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
+using System.Threading;
+using System;
+using NBitcoin.DataEncoders;
+using System.Text.Json.Serialization;
+
+namespace BTCPayServer.Controllers;
+
+public class UIBoltcardController : Controller
+{
+    public class BoltcardSettings
+    {
+        [JsonConverter(typeof(NBitcoin.JsonConverters.HexJsonConverter))]
+        public byte[]? IssuerKey { get; set; }
+    }
+    public UIBoltcardController(
+        UILNURLController lnUrlController,
+        SettingsRepository settingsRepository,
+        ApplicationDbContextFactory contextFactory,
+        BTCPayServerEnvironment env)
+    {
+        LNURLController = lnUrlController;
+        SettingsRepository = settingsRepository;
+        ContextFactory = contextFactory;
+        Env = env;
+    }
+
+    public UILNURLController LNURLController { get; }
+    public SettingsRepository SettingsRepository { get; }
+    public ApplicationDbContextFactory ContextFactory { get; }
+    public BTCPayServerEnvironment Env { get; }
+
+    [AllowAnonymous]
+    [HttpGet("~/boltcard")]
+    public async Task<IActionResult> GetWithdrawRequest([FromQuery] string? p, [FromQuery] string? c, [FromQuery] string? pr, [FromQuery] string? k1, CancellationToken cancellationToken)
+    {
+        if (p is null || c is null)
+        {
+            var k1s = k1?.Split('-');
+            if (k1s is not { Length: 2 })
+                return BadRequest(new LNUrlStatusResponse { Status = "ERROR", Reason = "Missing p, c, or k1 query parameter" });
+            p = k1s[0];
+            c = k1s[1];
+        }
+        var issuerKey = await SettingsRepository.GetIssuerKey(Env);
+        var piccData = issuerKey.TryDecrypt(p);
+        if (piccData is null)
+            return BadRequest(new LNUrlStatusResponse { Status = "ERROR", Reason = "Invalid PICCData" });
+
+        var registration = await ContextFactory.GetBoltcardRegistration(issuerKey, piccData, updateCounter: pr is not null);
+        if (registration?.PullPaymentId is null)
+            return BadRequest(new LNUrlStatusResponse { Status = "ERROR", Reason = "Replayed or expired query" });
+        var cardKey = issuerKey.CreateCardKey(piccData.Uid, registration.Version);
+        if (!cardKey.CheckSunMac(c, piccData))
+            return BadRequest(new LNUrlStatusResponse { Status = "ERROR", Reason = "Replayed or expired query" });
+        LNURLController.ControllerContext.HttpContext = HttpContext;
+        return await LNURLController.GetLNURLForPullPayment("BTC", registration.PullPaymentId, pr, $"{p}-{c}", cancellationToken);
+    }
+}