chore: sign update messages before sending

apps/server/prisma/migrations/20250129220359_add_update_signature/migration.sql

@@ -0,0 +1,30 @@
+/*
+  Warnings:
+
+  - Added the required column `accountId` to the `Update` table without a default value. This is not possible if the table is not empty.
+  - Added the required column `ephemeralId` to the `Update` table without a default value. This is not possible if the table is not empty.
+  - Added the required column `signatureHex` to the `Update` table without a default value. This is not possible if the table is not empty.
+  - Added the required column `signatureRecovery` to the `Update` table without a default value. This is not possible if the table is not empty.
+
+*/
+-- RedefineTables
+PRAGMA defer_foreign_keys=ON;
+PRAGMA foreign_keys=OFF;
+CREATE TABLE "new_Update" (
+    "spaceId" TEXT NOT NULL,
+    "clock" INTEGER NOT NULL,
+    "content" BLOB NOT NULL,
+    "accountId" TEXT NOT NULL,
+    "signatureHex" TEXT NOT NULL,
+    "signatureRecovery" INTEGER NOT NULL,
+    "ephemeralId" TEXT NOT NULL,
+
+    PRIMARY KEY ("spaceId", "clock"),
+    CONSTRAINT "Update_spaceId_fkey" FOREIGN KEY ("spaceId") REFERENCES "Space" ("id") ON DELETE RESTRICT ON UPDATE CASCADE,
+    CONSTRAINT "Update_accountId_fkey" FOREIGN KEY ("accountId") REFERENCES "Account" ("id") ON DELETE RESTRICT ON UPDATE CASCADE
+);
+INSERT INTO "new_Update" ("clock", "content", "spaceId") SELECT "clock", "content", "spaceId" FROM "Update";
+DROP TABLE "Update";
+ALTER TABLE "new_Update" RENAME TO "Update";
+PRAGMA foreign_keys=ON;
+PRAGMA defer_foreign_keys=OFF;

apps/server/prisma/migrations/migration_lock.toml

@@ -1,3 +1,3 @@
 # Please do not edit this file manually
-# It should be added in your version-control system (i.e. Git)
+# It should be added in your version-control system (e.g., Git)
 provider = "sqlite"

apps/server/prisma/schema.prisma

@@ -62,6 +62,7 @@ model Account {
   sessionNonce          String?
   sessionToken          String?
   sessionTokenExpires   DateTime?
+  updates               Update[]
 
   @@index([sessionToken])
 }
@@ -83,6 +84,11 @@ model Update {
   spaceId String
   clock   Int
   content Bytes
+  account           Account  @relation(fields: [accountId], references: [id])
+  accountId         String
+  signatureHex      String
+  signatureRecovery Int
+  ephemeralId       String
 
   @@id([spaceId, clock])
 }

apps/server/src/handlers/createUpdate.ts

@@ -4,9 +4,19 @@ type Params = {
   accountId: string;
   update: Uint8Array;
   spaceId: string;
+  signatureHex: string;
+  signatureRecovery: number;
+  ephemeralId: string;
 };
 
-export const createUpdate = async ({ accountId, update, spaceId }: Params) => {
+export const createUpdate = async ({
+  accountId,
+  update,
+  spaceId,
+  signatureHex,
+  signatureRecovery,
+  ephemeralId,
+}: Params) => {
   // throw error if account is not a member of the space
   await prisma.space.findUniqueOrThrow({
     where: { id: spaceId, members: { some: { id: accountId } } },
@@ -39,11 +49,14 @@ export const createUpdate = async ({ accountId, update, spaceId }: Params) => {
             spaceId,
             clock,
             content: Buffer.from(update),
+            signatureHex,
+            signatureRecovery,
+            ephemeralId,
+            account: { connect: { id: accountId } },
           },
         });
       });
       success = true;
-      return result;
     } catch (error) {
       const dbError = error as { code?: string; message?: string };
       if (dbError.code === 'P2034' || dbError.code === 'P1008' || dbError.message?.includes('database is locked')) {

apps/server/src/handlers/getSpace.ts

@@ -53,14 +53,26 @@ export const getSpace = async ({ spaceId, accountId }: Params) => {
     };
   });
 
+  const formatUpdate = (update) => {
+    return {
+      accountId: update.accountId,
+      update: new Uint8Array(update.content),
+      signature: {
+        hex: update.signatureHex,
+        recovery: update.signatureRecovery,
+      },
+      ephemeralId: update.ephemeralId,
+    };
+  };
+
   return {
     id: space.id,
     events: space.events.map((wrapper) => JSON.parse(wrapper.event)),
     keyBoxes,
     updates:
       space.updates.length > 0
         ? {
-            updates: space.updates.map((update) => new Uint8Array(update.content)),
+            updates: space.updates.map(formatUpdate),
             firstUpdateClock: space.updates[0].clock,
             lastUpdateClock: space.updates[space.updates.length - 1].clock,
           }

apps/server/src/index.ts

@@ -1,5 +1,6 @@
 import { parse } from 'node:url';
 import { Identity, Messages, SpaceEvents, Utils } from '@graphprotocol/hypergraph';
+import { recoverUpdateMessageSigner } from '@graphprotocol/hypergraph/messages/signed-update-message';
 import cors from 'cors';
 import { Effect, Exit, Schema } from 'effect';
 import express, { type Request, type Response } from 'express';
@@ -393,24 +394,49 @@ webSocketServer.on('connection', async (webSocket: CustomWebSocket, request: Req
           break;
         }
         case 'create-update': {
-          const update = await createUpdate({ accountId, spaceId: data.spaceId, update: data.update });
-          const outgoingMessage: Messages.ResponseUpdateConfirmed = {
-            type: 'update-confirmed',
-            ephemeralId: data.ephemeralId,
-            clock: update.clock,
-            spaceId: data.spaceId,
-          };
-          webSocket.send(Messages.serialize(outgoingMessage));
+          try {
+            // Check that the update was signed by a valid identity
+            // belonging to this accountId
+            const signer = recoverUpdateMessageSigner(data);
+            const identity = await getIdentity({ signaturePublicKey: signer });
+            if (identity.accountId !== accountId) {
+              throw new Error('Invalid signature');
+            }
+            const update = await createUpdate({
+              accountId,
+              spaceId: data.spaceId,
+              update: data.update,
+              signatureHex: data.signature.hex,
+              signatureRecovery: data.signature.recovery,
+              ephemeralId: data.ephemeralId,
+            });
+            const outgoingMessage: Messages.ResponseUpdateConfirmed = {
+              type: 'update-confirmed',
+              ephemeralId: data.ephemeralId,
+              clock: update.clock,
+              spaceId: data.spaceId,
+            };
+            webSocket.send(Messages.serialize(outgoingMessage));
 
-          broadcastUpdates({
-            spaceId: data.spaceId,
-            updates: {
-              updates: [new Uint8Array(update.content)],
-              firstUpdateClock: update.clock,
-              lastUpdateClock: update.clock,
-            },
-            currentClient: webSocket,
-          });
+            broadcastUpdates({
+              spaceId: data.spaceId,
+              updates: {
+                updates: [
+                  {
+                    accountId,
+                    update: data.update,
+                    signature: data.signature,
+                    ephemeralId: data.ephemeralId,
+                  },
+                ],
+                firstUpdateClock: update.clock,
+                lastUpdateClock: update.clock,
+              },
+              currentClient: webSocket,
+            });
+          } catch (err) {
+            console.error('Error creating update:', err);
+          }
           break;
         }
         default:

packages/hypergraph-react/src/HypergraphAppContext.tsx

@@ -2,6 +2,7 @@
 
 import * as automerge from '@automerge/automerge';
 import { uuid } from '@automerge/automerge';
+import type { DocHandle } from '@automerge/automerge-repo';
 import { RepoContext } from '@automerge/automerge-repo-react-hooks';
 import { Identity, Key, Messages, SpaceEvents, type SpaceStorageEntry, Utils, store } from '@graphprotocol/hypergraph';
 import { useSelector as useSelectorStore } from '@xstate/store/react';
@@ -464,11 +465,69 @@ export function HypergraphAppProvider({
   // Handle WebSocket messages in a separate effect
   useEffect(() => {
     if (!websocketConnection) return;
+    if (!accountId) {
+      console.error('No accountId found');
+      return;
+    }
     const encryptionPrivateKey = keys?.encryptionPrivateKey;
     if (!encryptionPrivateKey) {
       console.error('No encryption private key found');
       return;
     }
+    const signaturePrivateKey = keys?.signaturePrivateKey;
+    if (!signaturePrivateKey) {
+      console.error('No signature private key found.');
+      return;
+    }
+
+    const applyUpdates = async (
+      spaceId: string,
+      spaceSecretKey: string,
+      automergeDocHandle: DocHandle<unknown>,
+      updates: Messages.Updates,
+    ) => {
+      const verifiedUpdates = updates.updates.map(async (update) => {
+        const signer = Messages.recoverUpdateMessageSigner({
+          update: update.update,
+          spaceId,
+          ephemeralId: update.ephemeralId,
+          signature: update.signature,
+          accountId: update.accountId,
+        });
+        const authorIdentity = await getUserIdentity(update.accountId);
+        if (authorIdentity.signaturePublicKey !== signer) {
+          console.error(
+            `Received invalid signature, recovered signer is ${signer},
+            expected ${authorIdentity.signaturePublicKey}`,
+          );
+          return { valid: false, update: new Uint8Array([]) };
+        }
+        return {
+          valid: true,
+          update: Messages.decryptMessage({
+            nonceAndCiphertext: update.update,
+            secretKey: Utils.hexToBytes(spaceSecretKey),
+          }),
+        };
+      });
+
+      for (const updatePromise of verifiedUpdates) {
+        const update = await updatePromise;
+        if (update.valid) {
+          automergeDocHandle.update((existingDoc) => {
+            const [newDoc] = automerge.applyChanges(existingDoc, [update.update]);
+            return newDoc;
+          });
+        }
+      }
+
+      store.send({
+        type: 'applyUpdate',
+        spaceId,
+        firstUpdateClock: updates.firstUpdateClock,
+        lastUpdateClock: updates.lastUpdateClock,
+      });
+    };
 
     const onMessage = async (event: MessageEvent) => {
       const data = Messages.deserialize(event.data);
@@ -526,26 +585,7 @@ export function HypergraphAppProvider({
             }
 
             if (response.updates) {
-              const updates = response.updates?.updates.map((update) => {
-                return Messages.decryptMessage({
-                  nonceAndCiphertext: update,
-                  secretKey: Utils.hexToBytes(keys[0].key),
-                });
-              });
-
-              for (const update of updates) {
-                automergeDocHandle.update((existingDoc) => {
-                  const [newDoc] = automerge.applyChanges(existingDoc, [update]);
-                  return newDoc;
-                });
-              }
-
-              store.send({
-                type: 'applyUpdate',
-                spaceId: response.id,
-                firstUpdateClock: response.updates?.firstUpdateClock,
-                lastUpdateClock: response.updates?.lastUpdateClock,
-              });
+              await applyUpdates(response.id, keys[0].key, automergeDocHandle, response.updates);
             }
 
             automergeDocHandle.on('change', (result) => {
@@ -560,17 +600,14 @@ export function HypergraphAppProvider({
 
                 const ephemeralId = uuid();
 
-                const nonceAndCiphertext = Messages.encryptMessage({
-                  message: lastLocalChange,
-                  secretKey: Utils.hexToBytes(space.keys[0].key),
-                });
-
-                const messageToSend = {
-                  type: 'create-update',
+                const messageToSend = Messages.signedUpdateMessage({
+                  accountId,
                   ephemeralId,
-                  update: nonceAndCiphertext,
                   spaceId: space.id,
-                } as const satisfies Messages.RequestCreateUpdate;
+                  message: lastLocalChange,
+                  secretKey: space.keys[0].key,
+                  signaturePrivateKey,
+                });
                 websocketConnection.send(Messages.serialize(messageToSend));
               } catch (error) {
                 console.error('Error sending message', error);
@@ -631,25 +668,12 @@ export function HypergraphAppProvider({
               console.error('Space not found', response.spaceId);
               return;
             }
+            if (!space.automergeDocHandle) {
+              console.error('No automergeDocHandle found', response.spaceId);
+              return;
+            }
 
-            const automergeUpdates = response.updates.updates.map((update) => {
-              return Messages.decryptMessage({
-                nonceAndCiphertext: update,
-                secretKey: Utils.hexToBytes(space.keys[0].key),
-              });
-            });
-
-            space?.automergeDocHandle?.update((existingDoc) => {
-              const [newDoc] = automerge.applyChanges(existingDoc, automergeUpdates);
-              return newDoc;
-            });
-
-            store.send({
-              type: 'applyUpdate',
-              spaceId: response.spaceId,
-              firstUpdateClock: response.updates.firstUpdateClock,
-              lastUpdateClock: response.updates.lastUpdateClock,
-            });
+            await applyUpdates(response.spaceId, space.keys[0].key, space.automergeDocHandle, response.updates);
             break;
           }
           default: {
@@ -664,7 +688,7 @@ export function HypergraphAppProvider({
     return () => {
       websocketConnection.removeEventListener('message', onMessage);
     };
-  }, [websocketConnection, spaces, keys?.encryptionPrivateKey]);
+  }, [websocketConnection, spaces, accountId, keys?.encryptionPrivateKey, keys?.signaturePrivateKey]);
 
   const createSpaceForContext = async () => {
     if (!accountId) {

packages/hypergraph/src/messages/index.ts

@@ -1,4 +1,5 @@
 export * from './decrypt-message.js';
 export * from './encrypt-message.js';
 export * from './serialize.js';
+export * from './signed-update-message.js';
 export * from './types.js';