feat: implement `attachLdSignatureForRelays` to control signing of Relayed activities

.config/ci.yml

@@ -198,8 +198,10 @@ proxyRemoteFiles: true
 #   https://example.com/thumbnail.webp?thumbnail=1&url=https%3A%2F%2Fstorage.example.com%2Fpath%2Fto%2Fvideo.mp4
 #videoThumbnailGenerator: https://example.com
 
-# Sign to ActivityPub GET request (default: true)
+# Sign outgoing ActivityPub GET request (default: true)
 signToActivityPubGet: true
+# Sign outgoing ActivityPub Activities (default: true)
+attachLdSignatureForRelays: true
 # check that inbound ActivityPub GET requests are signed ("authorized fetch")
 checkActivityPubGetSignature: false
 

.config/docker_example.yml

@@ -270,8 +270,10 @@ proxyRemoteFiles: true
 #   https://example.com/thumbnail.webp?thumbnail=1&url=https%3A%2F%2Fstorage.example.com%2Fpath%2Fto%2Fvideo.mp4
 #videoThumbnailGenerator: https://example.com
 
-# Sign to ActivityPub GET request (default: true)
+# Sign outgoing ActivityPub GET request (default: true)
 signToActivityPubGet: true
+# Sign outgoing ActivityPub Activities (default: true)
+attachLdSignatureForRelays: true
 # check that inbound ActivityPub GET requests are signed ("authorized fetch")
 checkActivityPubGetSignature: false
 

.config/example.yml

@@ -285,8 +285,10 @@ proxyRemoteFiles: true
 #   https://example.com/thumbnail.webp?thumbnail=1&url=https%3A%2F%2Fstorage.example.com%2Fpath%2Fto%2Fvideo.mp4
 #videoThumbnailGenerator: https://example.com
 
-# Sign to ActivityPub GET request (default: true)
+# Sign outgoing ActivityPub GET request (default: true)
 signToActivityPubGet: true
+# Sign outgoing ActivityPub Activities (default: true)
+attachLdSignatureForRelays: true
 # check that inbound ActivityPub GET requests are signed ("authorized fetch")
 checkActivityPubGetSignature: false
 

chart/files/default.yml

@@ -208,8 +208,10 @@ id: "aidx"
 # Media Proxy
 #mediaProxy: https://example.com/proxy
 
-# Sign to ActivityPub GET request (default: true)
+# Sign outgoing ActivityPub GET request (default: true)
 signToActivityPubGet: true
+# Sign outgoing ActivityPub Activities (default: true)
+attachLdSignatureForRelays: true
 # check that inbound ActivityPub GET requests are signed ("authorized fetch")
 checkActivityPubGetSignature: false
 

packages/backend/src/config.ts

@@ -95,6 +95,7 @@ type Source = {
 	customMOTD?: string[];
 
 	signToActivityPubGet?: boolean;
+	attachLdSignatureForRelays?: boolean;
 	checkActivityPubGetSignature?: boolean;
 
 	perChannelMaxNoteCacheCount?: number;
@@ -161,6 +162,7 @@ export type Config = {
 	proxyRemoteFiles: boolean | undefined;
 	customMOTD: string[] | undefined;
 	signToActivityPubGet: boolean;
+	attachLdSignatureForRelays: boolean;
 	checkActivityPubGetSignature: boolean | undefined;
 
 	version: string;
@@ -291,6 +293,7 @@ export function loadConfig(): Config {
 		proxyRemoteFiles: config.proxyRemoteFiles,
 		customMOTD: config.customMOTD,
 		signToActivityPubGet: config.signToActivityPubGet ?? true,
+		attachLdSignatureForRelays: config.attachLdSignatureForRelays ?? true,
 		checkActivityPubGetSignature: config.checkActivityPubGetSignature,
 		mediaProxy: externalMediaProxy ?? internalMediaProxy,
 		externalMediaProxyEnabled: externalMediaProxy !== null && externalMediaProxy !== internalMediaProxy,

packages/backend/src/core/activitypub/ApRendererService.ts

@@ -9,7 +9,7 @@ import { In } from 'typeorm';
 import * as mfm from '@transfem-org/sfm-js';
 import {DI} from '@/di-symbols.js';
 import type {Config} from '@/config.js';
-import type { MiPartialLocalUser, MiLocalUser, MiPartialRemoteUser, MiRemoteUser, MiUser } from '@/models/User.js';
+import type {MiLocalUser, MiPartialLocalUser, MiPartialRemoteUser, MiRemoteUser, MiUser} from '@/models/User.js';
 import type {IMentionedRemoteUsers, MiNote} from '@/models/Note.js';
 import type {MiBlocking} from '@/models/Blocking.js';
 import type {MiRelay} from '@/models/Relay.js';
@@ -23,7 +23,14 @@ import { MfmService } from '@/core/MfmService.js';
 import {UserEntityService} from '@/core/entities/UserEntityService.js';
 import {DriveFileEntityService} from '@/core/entities/DriveFileEntityService.js';
 import type {MiUserKeypair} from '@/models/UserKeypair.js';
-import type { UsersRepository, UserProfilesRepository, NotesRepository, DriveFilesRepository, PollsRepository, InstancesRepository } from '@/models/_.js';
+import type {
+	DriveFilesRepository,
+	InstancesRepository,
+	NotesRepository,
+	PollsRepository,
+	UserProfilesRepository,
+	UsersRepository
+} from '@/models/_.js';
 import {bindThis} from '@/decorators.js';
 import {CustomEmojiService} from '@/core/CustomEmojiService.js';
 import {isNotNull} from '@/misc/is-not-null.js';
@@ -32,7 +39,33 @@ import { MetaService } from '../MetaService.js';
 import {JsonLdService} from './JsonLdService.js';
 import {ApMfmService} from './ApMfmService.js';
 import {CONTEXT} from './misc/contexts.js';
-import type { IAccept, IActivity, IAdd, IAnnounce, IApDocument, IApEmoji, IApHashtag, IApImage, IApMention, IBlock, ICreate, IDelete, IFlag, IFollow, IKey, ILike, IMove, IObject, IPost, IQuestion, IReject, IRemove, ITombstone, IUndo, IUpdate } from './type.js';
+import type {
+	IAccept,
+	IActivity,
+	IAdd,
+	IAnnounce,
+	IApDocument,
+	IApEmoji,
+	IApHashtag,
+	IApImage,
+	IApMention,
+	IBlock,
+	ICreate,
+	IDelete,
+	IFlag,
+	IFollow,
+	IKey,
+	ILike,
+	IMove,
+	IObject,
+	IPost,
+	IQuestion,
+	IReject,
+	IRemove,
+	ITombstone,
+	IUndo,
+	IUpdate
+} from './type.js';
 
 @Injectable()
 export class ApRendererService {
@@ -793,6 +826,12 @@ export class ApRendererService {
 
 	@bindThis
 	public async attachLdSignature(activity: any, user: { id: MiUser['id']; host: null; }): Promise<IActivity> {
+		// When using authorized fetch, Linked Data signatures are often undesired (as it can allow blocked instances to bypass the check).
+		// We allow admins to disable LD signatures for increased privacy, at the expense of increased incoming fetch (GET) requests.
+		if (!this.config.attachLdSignatureForRelays) {
+			return activity;
+		}
+
 		const keypair = await this.userKeypairService.getUserKeypair(user.id);
 
 		const jsonLd = this.jsonLdService.use();