SocialPub/PrivaPub.Tests/Federation/IntegrityProofTests.cs

using MongoDB.Entities;

using PrivaPub.Federation.Actors;
using PrivaPub.Federation.Rendering;
using PrivaPub.Federation.Signing;
using PrivaPub.Models.Federation;
using PrivaPub.Models.User;
using PrivaPub.Tests.Support;

using System.Text;
using System.Text.Json.Nodes;

namespace PrivaPub.Tests.Federation
{
	// FEP-8b32 proofs (eddsa-jcs-2022) by a persona's Ed25519 key, which its actor names as a FEP-521a Multikey
	public sealed class IntegrityProofTests
	{
		[Fact]
		public void Canonical_json_is_rfc_8785s()
		{
			// RFC 8785, section 3.2.2
			var input = JsonNode.Parse("{\"numbers\":[333333333.33333329,1E30,4.50,2e-3,0.000000000000000000000000001],"
				+ "\"string\":\"\\u20ac$\\u000F\\u000aA'\\u0042\\u0022\\u005c\\\\\\\"\\/\",\"literals\":[null,true,false]}");

			Assert.Equal("{\"literals\":[null,true,false],\"numbers\":[333333333.3333333,1e+30,4.5,0.002,1e-27],\"string\":\"€$\\u000f\\nA'B\\\"\\\\\\\\\\\"/\"}",
				Jcs.Serialize(input));
		}

		[Fact]
		public void Base58_and_multikeys_read_back_what_they_write()
		{
			Assert.Equal("2NEpo7TZRRrLZSi2U", IntegrityProofs.Base58(Encoding.ASCII.GetBytes("Hello World!")));
			Assert.Equal("112", IntegrityProofs.Base58(new byte[] { 0, 0, 1 }));
			Assert.Equal(new byte[] { 0, 0, 1 }, IntegrityProofs.FromBase58("112"));

			var publicKey = IntegrityProofs.PublicKey(IntegrityProofs.NewSeed());
			var multikey = IntegrityProofs.Multikey(publicKey);
			Assert.StartsWith("z6Mk", multikey);
			Assert.Equal(publicKey, IntegrityProofs.FromMultikey(multikey));
		}

		[Fact]
		public void A_proof_verifies_with_its_key_and_with_nothing_changed()
		{
			var seed = IntegrityProofs.NewSeed();
			var activity = new JsonObject
			{
				["@context"] = ActivityPubRenderer.Context(), ["id"] = "https://privapub.test/peasants/alice/grunts/1", ["type"] = "Create",
				["actor"] = "https://privapub.test/peasants/alice", ["object"] = new JsonObject { ["type"] = "Note", ["content"] = "<p>ciao, è così</p>", ["width"] = 4.5 }
			};
			activity["proof"] = IntegrityProofs.Create(activity, "https://privapub.test/peasants/alice#ed25519-key", seed, DateTime.UtcNow);

			var delivered = JsonNode.Parse(activity.ToJsonString())!.AsObject();
			Assert.True(IntegrityProofs.Verify(delivered, IntegrityProofs.PublicKey(seed)));
			Assert.Equal("assertionMethod", delivered["proof"]!["proofPurpose"]!.GetValue<string>());

			var changed = delivered.DeepClone().AsObject();
			changed["object"]!["content"] = "<p>something else</p>";
			Assert.False(IntegrityProofs.Verify(changed, IntegrityProofs.PublicKey(seed)));
			Assert.False(IntegrityProofs.Verify(delivered, IntegrityProofs.PublicKey(IntegrityProofs.NewSeed())));
		}

		[Fact]
		public void A_persona_with_a_key_names_it_as_a_multikey()
		{
			var seed = IntegrityProofs.NewSeed();
			var actor = ActivityPubRenderer.Actor(new LocalActor { Id = "a", UserName = "alice", BaseAddress = Harness.Base, Kind = LocalActorKind.Person, SigningKey = seed });
			var keyless = ActivityPubRenderer.Actor(new LocalActor { Id = "b", UserName = "bob", BaseAddress = Harness.Base, Kind = LocalActorKind.Person });

			var key = Assert.Single(actor["assertionMethod"]!.AsArray())!;
			Assert.Equal(($"{Harness.Base}/peasants/alice#ed25519-key", "Multikey", $"{Harness.Base}/peasants/alice"),
				(key["id"]!.GetValue<string>(), key["type"]!.GetValue<string>(), key["controller"]!.GetValue<string>()));
			Assert.Equal(IntegrityProofs.PublicKey(seed), IntegrityProofs.FromMultikey(key["publicKeyMultibase"]!.GetValue<string>()));
			Assert.Null(keyless["assertionMethod"]);
		}
	}

	[Trait("Category", "Integration")]
	[Xunit.Collection(nameof(Exclusive))]
	public sealed class DeliveredProofTests : IAsyncLifetime
	{
		Harness _harness;

		public async ValueTask InitializeAsync()
		{
			Assert.SkipUnless(MongoFixture.Enabled, MongoFixture.Skip);
			_harness = await Harness.Start();
		}

		public async ValueTask DisposeAsync()
		{
			if (_harness != default)
				await _harness.DisposeAsync();
		}

		// what goes to a relay carries the persona's proof, to be forwarded on its strength; what goes to a server directly
		// does not (Mitra refuses a proof by a key it has not read yet); another's activity passed on never gets ours
		[Fact]
		public async Task A_personas_activity_goes_to_a_relay_with_its_proof_and_elsewhere_without()
		{
			var token = TestContext.Current.CancellationToken;
			var (_, persona) = await _harness.Persona("alice");
			var seed = IntegrityProofs.NewSeed();
			await DB.Default.Update<Avatar>().MatchID(persona.Id).Modify(a => a.SigningKey, seed).ExecuteAsync(token);
			var alice = _harness.Local.FromAvatar(await DB.Default.Find<Avatar>().MatchID(persona.Id).ExecuteSingleAsync(token));
			var relayInbox = $"{_harness.Peer.A}/relay-{Guid.NewGuid():N}/inbox";
			var serverInbox = _harness.Peer.A + "/proofs/inbox";
			await DB.Default.SaveAsync(new RelaySubscription
			{
				Configured = relayInbox, ActorURI = relayInbox.Replace("/inbox", "/actor"), InboxURL = relayInbox, State = RelayState.Accepted
			}, token);
			var own = new JsonObject { ["id"] = alice.ActivityUri(Guid.NewGuid().ToString("N")), ["type"] = "Create", ["actor"] = alice.Uri, ["object"] = new JsonObject { ["type"] = "Note" } };
			var passedOn = new JsonObject { ["id"] = $"https://elsewhere.example/activities/{Guid.NewGuid():N}", ["type"] = "Create", ["actor"] = "https://elsewhere.example/users/bob" };

			try
			{
				await _harness.Delivery.Enqueue(alice, new[] { relayInbox, serverInbox }, own, token);
				await _harness.Delivery.Enqueue(alice, new[] { relayInbox }, passedOn, token);

				var toRelay = await _harness.Outgoing(relayInbox);
				var signed = Assert.Single(toRelay, a => a["actor"]!.GetValue<string>() == alice.Uri);
				Assert.Equal(alice.AssertionKeyId, signed["proof"]!["verificationMethod"]!.GetValue<string>());
				Assert.True(IntegrityProofs.Verify(signed, IntegrityProofs.PublicKey(seed)));
				Assert.Null(Assert.Single(toRelay, a => a["actor"]!.GetValue<string>() != alice.Uri)["proof"]);
				Assert.Null(Assert.Single(await _harness.Outgoing(serverInbox))["proof"]);
				Assert.Null(own["proof"]);
			}
			finally
			{
				await DB.Default.DeleteAsync<RelaySubscription>(s => s.InboxURL == relayInbox);
			}
		}

		// a post forwarded by another server, which its origin does not serve: taken on its author's proof, never without
		[Fact]
		public async Task A_forwarded_post_with_its_authors_proof_is_taken_as_it_came()
		{
			var token = TestContext.Current.CancellationToken;
			var (_, alice) = await _harness.Persona("alice");
			var author = new RemoteActor(_harness.Peer, "author", ed25519: true);
			var forwarder = new RemoteActor(_harness.Peer, "forwarder", _harness.Peer.B);
			await DB.Default.SaveAsync(new PrivaPub.Models.Social.Following
			{
				AvatarId = alice.Id, TargetActorURI = author.Id, TargetInboxURL = author.Id + "/inbox", State = PrivaPub.Models.Social.FollowState.Accepted
			}, token);
			JsonObject Create(string text)
			{
				var noteId = $"{new Uri(author.Id).GetLeftPart(UriPartial.Authority)}/notes/{Guid.NewGuid():N}";
				return new JsonObject
				{
					["@context"] = "https://www.w3.org/ns/activitystreams", ["id"] = noteId + "/activity", ["type"] = "Create", ["actor"] = author.Id,
					["to"] = new JsonArray("https://www.w3.org/ns/activitystreams#Public"),
					["object"] = new JsonObject
					{
						["id"] = noteId, ["type"] = "Note", ["attributedTo"] = author.Id, ["content"] = $"<p>{text}</p>",
						["to"] = new JsonArray("https://www.w3.org/ns/activitystreams#Public"), ["published"] = DateTime.UtcNow.ToString("O")
					}
				};
			}
			var proven = author.Prove(Create("proven"));
			var tampered = author.Prove(Create("as written"));
			tampered["object"]!["content"] = "<p>changed on the way</p>";
			var bare = Create("unproven");

			await _harness.Deliver(forwarder, "/human-centipede", proven);
			await _harness.Deliver(forwarder, "/human-centipede", tampered);
			await _harness.Deliver(forwarder, "/human-centipede", bare);

			Task<bool> Held(JsonObject create) => DB.Default.Find<PrivaPub.Models.Post.Post>().Match(p => p.ObjectURI == create["object"]!["id"]!.GetValue<string>()).ExecuteAnyAsync(token);
			Assert.True(await Held(proven));
			Assert.False(await Held(tampered));
			Assert.False(await Held(bare));
		}
	}
}