merge: feat: implement attachLdSignatureForRelays to control signing of Relayed activities (#599) (!579)

View MR for information: https://activitypub.software/TransFem-org/Sharkey/-/merge_requests/579

Closes #599

Approved-by: dakkar <dakkar@thenautilus.net>
Approved-by: Marie <marie@kaifa.ch>

.config/ci.yml

@@ -198,8 +198,13 @@ 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)
+# Linked Data signatures are cryptographic signatures attached to each activity to provide proof of authenticity.
+# When using authorized fetch, this is often undesired as any signed activity can be forwarded to a blocked instance by relays and other instances.
+# This setting allows admins to disable LD signatures for increased privacy, at the expense of fewer relayed activities and additional inbound fetch (GET) requests.
+attachLdSignatureForRelays: true
 # check that inbound ActivityPub GET requests are signed ("authorized fetch")
 checkActivityPubGetSignature: false
 

.config/docker_example.yml

@@ -270,8 +270,13 @@ 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)
+# Linked Data signatures are cryptographic signatures attached to each activity to provide proof of authenticity.
+# When using authorized fetch, this is often undesired as any signed activity can be forwarded to a blocked instance by relays and other instances.
+# This setting allows admins to disable LD signatures for increased privacy, at the expense of fewer relayed activities and additional inbound fetch (GET) requests.
+attachLdSignatureForRelays: true
 # check that inbound ActivityPub GET requests are signed ("authorized fetch")
 checkActivityPubGetSignature: false
 

.config/example.yml

@@ -285,8 +285,13 @@ 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)
+# Linked Data signatures are cryptographic signatures attached to each activity to provide proof of authenticity.
+# When using authorized fetch, this is often undesired as any signed activity can be forwarded to a blocked instance by relays and other instances.
+# This setting allows admins to disable LD signatures for increased privacy, at the expense of fewer relayed activities and additional inbound fetch (GET) requests.
+attachLdSignatureForRelays: true
 # check that inbound ActivityPub GET requests are signed ("authorized fetch")
 checkActivityPubGetSignature: false
 

chart/files/default.yml

@@ -208,8 +208,13 @@ 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)
+# Linked Data signatures are cryptographic signatures attached to each activity to provide proof of authenticity.
+# When using authorized fetch, this is often undesired as any signed activity can be forwarded to a blocked instance by relays and other instances.
+# This setting allows admins to disable LD signatures for increased privacy, at the expense of fewer relayed activities and additional inbound fetch (GET) requests.
+attachLdSignatureForRelays: true
 # check that inbound ActivityPub GET requests are signed ("authorized fetch")
 checkActivityPubGetSignature: false
 

packages/backend/src/config.ts

@@ -96,6 +96,7 @@ type Source = {
 	customMOTD?: string[];
 
 	signToActivityPubGet?: boolean;
+	attachLdSignatureForRelays?: boolean;
 	checkActivityPubGetSignature?: boolean;
 
 	perChannelMaxNoteCacheCount?: number;
@@ -162,6 +163,7 @@ export type Config = {
 	proxyRemoteFiles: boolean | undefined;
 	customMOTD: string[] | undefined;
 	signToActivityPubGet: boolean;
+	attachLdSignatureForRelays: boolean;
 	checkActivityPubGetSignature: boolean | undefined;
 
 	version: string;
@@ -299,6 +301,7 @@ 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

@@ -793,6 +793,13 @@ export class ApRendererService {
 
 	@bindThis
 	public async attachLdSignature(activity: any, user: { id: MiUser['id']; host: null; }): Promise<IActivity> {
+		// Linked Data signatures are cryptographic signatures attached to each activity to provide proof of authenticity.
+		// When using authorized fetch, this is often undesired as any signed activity can be forwarded to a blocked instance by relays and other instances.
+		// This setting allows admins to disable LD signatures for increased privacy, at the expense of fewer relayed activities and additional inbound fetch (GET) requests.
+		if (!this.config.attachLdSignatureForRelays) {
+			return activity;
+		}
+
 		const keypair = await this.userKeypairService.getUserKeypair(user.id);
 
 		const jsonLd = this.jsonLdService.use();