[backend/federation] Make LD signatures configurable

Iceshrimp.Backend/Core/Configuration/Config.cs

@@ -49,6 +49,8 @@ public sealed class Config
 	public sealed class SecuritySection
 	{
 		public bool                 AuthorizedFetch      { get; init; } = true;
+		public bool                 AttachLdSignatures   { get; init; } = false;
+		public bool                 AcceptLdSignatures   { get; init; } = false;
 		public ExceptionVerbosity   ExceptionVerbosity   { get; init; } = ExceptionVerbosity.Basic;
 		public Enums.Registrations  Registrations        { get; init; } = Enums.Registrations.Closed;
 		public Enums.FederationMode FederationMode       { get; init; } = Enums.FederationMode.BlockList;

Iceshrimp.Backend/Core/Federation/ActivityStreams/LDHelpers.cs

@@ -104,6 +104,14 @@ public static class LdHelpers
 		return payload;
 	}
 	
+	public static async Task<string> CompactAsync(this ASActivity activity)
+	{
+		var compacted = Compact(activity) ?? throw new Exception("Failed to compact signed activity");
+		var payload   = JsonConvert.SerializeObject(compacted, JsonSerializerSettings);
+
+		return payload;
+	}
+
 	public static JObject? Compact(object obj)
 	{
 		return Compact(JToken.FromObject(obj, JsonSerializer));

Iceshrimp.Backend/Core/Middleware/AuthorizedFetchMiddleware.cs

@@ -116,7 +116,9 @@ public class AuthorizedFetchMiddleware(
 				logger.LogDebug("Error validating HTTP signature: {error}", e.Message);
 			}
 
-			if (!verified && request is { ContentType: not null, ContentLength: > 0 })
+			if (!verified &&
+			    request is { ContentType: not null, ContentLength: > 0 } &&
+			    config.Value.AcceptLdSignatures)
 			{
 				logger.LogDebug("Trying LD signature next...");
 				try

Iceshrimp.Backend/Core/Queues/PreDeliverQueue.cs

@@ -1,9 +1,11 @@
 using System.Diagnostics.CodeAnalysis;
+using Iceshrimp.Backend.Core.Configuration;
 using Iceshrimp.Backend.Core.Database;
 using Iceshrimp.Backend.Core.Federation.ActivityStreams;
 using Iceshrimp.Backend.Core.Federation.ActivityStreams.Types;
 using Iceshrimp.Backend.Core.Services;
 using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Options;
 using Newtonsoft.Json.Linq;
 using ProtoBuf;
 using StackExchange.Redis;
@@ -24,6 +26,7 @@ public class PreDeliverQueue
 		var logger   = scope.GetRequiredService<ILogger<DeliverQueue>>();
 		var db       = scope.GetRequiredService<DatabaseContext>();
 		var queueSvc = scope.GetRequiredService<QueueService>();
+		var config   = scope.GetRequiredService<IOptionsSnapshot<Config.SecuritySection>>();
 
 		var parsed       = JToken.Parse(job.SerializedActivity);
 		var expanded     = LdHelpers.Expand(parsed) ?? throw new Exception("Failed to expand activity");
@@ -64,8 +67,16 @@ public class PreDeliverQueue
 
 		if (inboxQueryResults.Count == 0) return;
 
+		string payload;
+		if (config.Value.AttachLdSignatures)
+		{
 			var keypair = await db.UserKeypairs.FirstAsync(p => p.UserId == job.ActorId, token);
-		var payload = await activity.SignAndCompactAsync(keypair);
+			payload = await activity.SignAndCompactAsync(keypair);
+		}
+		else
+		{
+			payload = await activity.CompactAsync();
+		}
 
 		foreach (var inboxQueryResult in inboxQueryResults)
 			await queueSvc.DeliverQueue.EnqueueAsync(new DeliverJob

Iceshrimp.Backend/configuration.ini

@@ -18,6 +18,12 @@ CharacterLimit = 8192
 ;; It is highly recommend you keep this enabled if you intend to use block- or allowlist federation
 AuthorizedFetch = true
 
+;; Whether to attach LD signatures to outgoing activities
+AttachLdSignatures = false
+
+;; Whether to accept activities signed using LD signatures
+AcceptLdSignatures = false
+
 ;; The level of detail in API error responses
 ;; Options: [None, Basic, Full]
 ExceptionVerbosity = Basic