handle userGroupEncBucketKey for external users in CryptoFacade, see server issue 1313

schemas/sys.json

@@ -50,6 +50,21 @@
 					"info": "AddValue CustomerProperties/usageDataOptedOut/2025."
 				}
 			]
+		},
+		{
+			"version": 83,
+			"changes": [
+				{
+					"name": "RenameAttribute",
+					"sourceType": "BucketKey",
+					"info": "RenameAttribute BucketKey: pubKeyGroup -> keyGroup."
+				},
+				{
+					"name": "RenameAttribute",
+					"sourceType": "BucketKey",
+					"info": "RenameAttribute BucketKey: ownerEncBucketKey -> groupEncBucketKey."
+				}
+			]
 		}
 	]
 }

src/api/entities/sys/ModelInfo.ts

@@ -1,6 +1,6 @@
 const modelInfo = {
-	version: 82,
-	compatibleSince: 80,
+	version: 83,
+	compatibleSince: 83,
 }
 		
 export default modelInfo

src/api/entities/sys/TypeRefs.ts

@@ -456,11 +456,11 @@ export type BucketKey = {
 	_type: TypeRef<BucketKey>;
 
 	_id: Id;
-	ownerEncBucketKey: null | Uint8Array;
+	groupEncBucketKey: null | Uint8Array;
 	pubEncBucketKey: null | Uint8Array;
 
 	bucketEncSessionKeys: InstanceSessionKey[];
-	pubKeyGroup:  null | Id;
+	keyGroup:  null | Id;
 }
 export const BucketPermissionTypeRef: TypeRef<BucketPermission> = new TypeRef("sys", "BucketPermission")
 

src/api/entities/tutanota/ModelInfo.ts

@@ -1,5 +1,5 @@
 const modelInfo = {
-	version: 59,
+	version: 60,
 	compatibleSince: 58,
 }
 		

src/api/worker/crypto/CryptoFacade.ts

@@ -300,12 +300,21 @@ export class CryptoFacade {
 		const instanceElementId = this.getElementIdFromInstance(instance)
 
 		let decBucketKey: Aes128Key
-		if (bucketKey.pubKeyGroup && bucketKey.pubEncBucketKey) {
+		if (bucketKey.keyGroup && bucketKey.pubEncBucketKey) {
 			// bucket key is encrypted with public key for internal recipient
-			decBucketKey = await this.decryptBucketKeyWithKeyPairOfGroup(bucketKey.pubKeyGroup, bucketKey.pubEncBucketKey)
-		} else if (bucketKey.ownerEncBucketKey) {
+			decBucketKey = await this.decryptBucketKeyWithKeyPairOfGroup(bucketKey.keyGroup, bucketKey.pubEncBucketKey)
+		} else if (bucketKey.groupEncBucketKey) {
 			// secure external recipient
-			decBucketKey = decryptKey(this.userFacade.getGroupKey(neverNull(instance._ownerGroup)), bucketKey.ownerEncBucketKey)
+			let keyGroup
+			if (bucketKey.keyGroup) {
+				// legacy code path for old external clients that used to encrypt bucket keys with user group keys.
+				// should be dropped once all old external mailboxes are cleared
+				keyGroup = bucketKey.keyGroup
+			} else {
+				// by default, we try to decrypt the bucket key with the ownerGroupKey
+				keyGroup = neverNull(instance._ownerGroup)
+			}
+			decBucketKey = decryptKey(this.userFacade.getGroupKey(keyGroup), bucketKey.groupEncBucketKey)
 		} else {
 			throw new SessionKeyNotFoundError(`encrypted bucket key not set on instance ${typeModel.name}`)
 		}

src/api/worker/offline/OfflineStorageMigrator.ts

@@ -14,6 +14,7 @@ import { tutanota58 } from "./migrations/tutanota-v58.js"
 import { storage6 } from "./migrations/storage-v6.js"
 import { tutanota57 } from "./migrations/tutanota-v57.js"
 import { OutOfSyncError } from "../../common/error/OutOfSyncError.js"
+import { sys83 } from "./migrations/sys-v83.js"
 
 export interface OfflineMigration {
 	readonly app: VersionMetadataBaseKey
@@ -39,6 +40,7 @@ export const OFFLINE_STORAGE_MIGRATIONS: ReadonlyArray<OfflineMigration> = [
 	tutanota57,
 	tutanota58,
 	storage6,
+	sys83,
 ]
 
 const CURRENT_OFFLINE_VERSION = 1

src/api/worker/offline/StandardMigrations.ts

@@ -27,7 +27,7 @@ export async function migrateAllElements<T extends ElementEntity>(typeRef: TypeR
 	}
 }
 
-type Migration<T extends SomeEntity> = (entity: any) => T
+export type Migration<T extends SomeEntity> = (entity: any) => T
 
 export function renameAttribute<T extends SomeEntity>(oldName: string, newName: keyof T): Migration<T> {
 	return function (entity) {

src/api/worker/offline/migrations/sys-v83.ts

@@ -0,0 +1,25 @@
+import { OfflineMigration } from "../OfflineStorageMigrator.js"
+import { OfflineStorage } from "../OfflineStorage.js"
+import { migrateAllListElements, Migration } from "../StandardMigrations.js"
+import { Mail, MailTypeRef } from "../../../entities/tutanota/TypeRefs.js"
+
+export const sys83: OfflineMigration = {
+	app: "sys",
+	version: 83,
+	async migrate(storage: OfflineStorage) {
+		await migrateAllListElements(MailTypeRef, storage, [migrateBucketKey()])
+	},
+}
+
+function migrateBucketKey(): Migration<Mail> {
+	return function (mail) {
+		const bucketKey = mail.bucketKey
+		if (bucketKey != null) {
+			bucketKey["keyGroup"] = bucketKey["pubKeyGroup"]
+			delete bucketKey["pubKeyGroup"]
+			bucketKey["groupEncBucketKey"] = bucketKey["ownerEncBucketKey"]
+			delete bucketKey["ownerEncBucketKey"]
+		}
+		return mail
+	}
+}

test/tests/api/worker/crypto/CryptoFacadeTest.ts

@@ -896,7 +896,7 @@ o.spec("crypto facade", function () {
 	})
 
 	o(
-		"resolve session key: external user key decryption of session key using BucketKey aggregated type - Mail referencing MailDetailsBlob with attachments",
+		"resolve session key: external user key decryption of session key using BucketKey aggregated type encrypted with MailGroupKey - Mail referencing MailDetailsBlob with attachments",
 		async function () {
 			o.timeout(500) // in CI or with debugging it can take a while
 			const file1SessionKey = aes128RandomKey()
@@ -914,6 +914,25 @@ o.spec("crypto facade", function () {
 		},
 	)
 
+	o(
+		"resolve session key: external user key decryption of session key using BucketKey aggregated type encrypted with UserGroupKey - Mail referencing MailDetailsBlob with attachments",
+		async function () {
+			o.timeout(500) // in CI or with debugging it can take a while
+			const file1SessionKey = aes128RandomKey()
+			const file2SessionKey = aes128RandomKey()
+			const testData = await prepareSymEncBucketKeyResolveSessionKeyTest([file1SessionKey, file2SessionKey], true)
+			Object.assign(testData.mailLiteral, { mailDetails: ["mailDetailsArchiveId", "mailDetailsId"] })
+
+			const mailSessionKey = neverNull(await crypto.resolveSessionKey(testData.MailTypeModel, testData.mailLiteral))
+
+			o(mailSessionKey).deepEquals(testData.sk)
+			o(Object.keys(crypto.getSessionKeyCache()).length).equals(3)
+			o(crypto.getSessionKeyCache()["mailDetailsId"]).deepEquals(testData.sk)
+			o(crypto.getSessionKeyCache()["fileId1"]).deepEquals(file1SessionKey)
+			o(crypto.getSessionKeyCache()["fileId2"]).deepEquals(file2SessionKey)
+		},
+	)
+
 	o("resolve session key from cache: MailDetailsBlob", async function () {
 		const sk = aes128RandomKey()
 		crypto.getSessionKeyCache()["mailDetailsId"] = sk
@@ -1019,7 +1038,7 @@ o.spec("crypto facade", function () {
 
 		const bucketKey = createBucketKey({
 			pubEncBucketKey: pubEncBucketKey,
-			pubKeyGroup: userGroup._id,
+			keyGroup: userGroup._id,
 			bucketEncSessionKeys: bucketEncSessionKeys,
 		})
 
@@ -1060,7 +1079,10 @@ o.spec("crypto facade", function () {
 	 *
 	 * @param fileSessionKeys List of session keys for the attachments. When the list is empty there are no attachments
 	 */
-	async function prepareSymEncBucketKeyResolveSessionKeyTest(fileSessionKeys: Array<Aes128Key> = []): Promise<{
+	async function prepareSymEncBucketKeyResolveSessionKeyTest(
+		fileSessionKeys: Array<Aes128Key> = [],
+		externalUserGroupEncBucketKey = false,
+	): Promise<{
 		mailLiteral: Record<string, any>
 		sk: Aes128Key
 		bk: Aes128Key
@@ -1073,6 +1095,7 @@ o.spec("crypto facade", function () {
 		let gk = aes128RandomKey()
 		let sk = aes128RandomKey()
 		let bk = aes128RandomKey()
+		const ugk = aes128RandomKey()
 
 		const userGroup = createGroup({
 			_id: "userGroupId",
@@ -1080,9 +1103,11 @@ o.spec("crypto facade", function () {
 		})
 		const mailLiteral = createMailLiteral(gk, sk, subject, confidential, senderName, recipientName)
 		// @ts-ignore
-		mailLiteral._ownerEncSessionKey = null
 
-		const ownerEncBucketKey = encryptKey(gk, bk)
+		mailLiteral._ownerEncSessionKey = null
+		const groupKeyToEncryptBucketKey = externalUserGroupEncBucketKey ? ugk : gk
+
+		const groupEncBucketKey = encryptKey(groupKeyToEncryptBucketKey, bk)
 		const bucketEncMailSessionKey = encryptKey(bk, sk)
 
 		const MailTypeModel = await resolveTypeReference(MailTypeRef)
@@ -1113,8 +1138,8 @@ o.spec("crypto facade", function () {
 
 		const bucketKey = createBucketKey({
 			pubEncBucketKey: null,
-			pubKeyGroup: null,
-			ownerEncBucketKey: ownerEncBucketKey,
+			keyGroup: externalUserGroupEncBucketKey ? userGroup._id : null,
+			groupEncBucketKey: groupEncBucketKey,
 			bucketEncSessionKeys: bucketEncSessionKeys,
 		})
 
@@ -1132,6 +1157,7 @@ o.spec("crypto facade", function () {
 
 		when(userFacade.getLoggedInUser()).thenReturn(user)
 		when(userFacade.getGroupKey("mailGroupId")).thenReturn(gk)
+		when(userFacade.getGroupKey(userGroup._id)).thenReturn(ugk)
 		when(userFacade.isLeader()).thenReturn(true)
 
 		when(entityClient.load(GroupTypeRef, userGroup._id)).thenResolve(userGroup)