Attachments: support for incrementalMac and chunkSize

ts/test-electron/ContactsParser_test.ts

@@ -44,10 +44,11 @@ describe('ContactsParser', () => {
         const keys = generateKeys();
 
         ({ path } = await encryptAttachmentV2ToDisk({
-          plaintext: { data },
           keys,
           getAbsoluteAttachmentPath:
             window.Signal.Migrations.getAbsoluteAttachmentPath,
+          needIncrementalMac: false,
+          plaintext: { data },
         }));
 
         const contacts = await parseContactsV2({

ts/test-electron/Crypto_test.ts

@@ -1,11 +1,13 @@
 // Copyright 2015 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
-import { assert } from 'chai';
 import { readFileSync, unlinkSync, writeFileSync } from 'fs';
 import { join } from 'path';
-
 import { createCipheriv } from 'crypto';
+
+import { assert } from 'chai';
+import { isNumber } from 'lodash';
+
 import * as log from '../logging/log';
 import * as Bytes from '../Bytes';
 import * as Curve from '../Curve';
@@ -584,6 +586,8 @@ describe('Crypto', () => {
           ...splitKeys(keys),
           size: FILE_CONTENTS.byteLength,
           theirDigest: encryptedAttachment.digest,
+          theirIncrementalMac: undefined,
+          theirChunkSize: undefined,
           getAbsoluteAttachmentPath:
             window.Signal.Migrations.getAbsoluteAttachmentPath,
         });
@@ -611,6 +615,7 @@ describe('Crypto', () => {
         plaintextHash,
         encryptionKeys,
         dangerousIv,
+        modifyIncrementalMac,
         overrideSize,
       }: {
         path?: string;
@@ -618,6 +623,7 @@ describe('Crypto', () => {
         plaintextHash?: Uint8Array;
         encryptionKeys?: Uint8Array;
         dangerousIv?: HardcodedIVForEncryptionType;
+        modifyIncrementalMac?: boolean;
         overrideSize?: number;
       }): Promise<DecryptedAttachmentV2> {
         let plaintextPath;
@@ -631,12 +637,22 @@ describe('Crypto', () => {
             dangerousIv,
             getAbsoluteAttachmentPath:
               window.Signal.Migrations.getAbsoluteAttachmentPath,
+            needIncrementalMac: true,
           });
 
           ciphertextPath = window.Signal.Migrations.getAbsoluteAttachmentPath(
             encryptedAttachment.path
           );
 
+          const macLength = encryptedAttachment.incrementalMac?.length;
+          if (
+            modifyIncrementalMac &&
+            isNumber(macLength) &&
+            encryptedAttachment.incrementalMac
+          ) {
+            encryptedAttachment.incrementalMac[macLength / 2] += 1;
+          }
+
           const decryptedAttachment = await decryptAttachmentV2({
             type: 'standard',
             ciphertextPath,
@@ -644,6 +660,8 @@ describe('Crypto', () => {
             ...splitKeys(keys),
             size: overrideSize ?? data.byteLength,
             theirDigest: encryptedAttachment.digest,
+            theirIncrementalMac: encryptedAttachment.incrementalMac,
+            theirChunkSize: encryptedAttachment.chunkSize,
             getAbsoluteAttachmentPath:
               window.Signal.Migrations.getAbsoluteAttachmentPath,
           });
@@ -736,6 +754,25 @@ describe('Crypto', () => {
           unlinkSync(sourcePath);
         }
       });
+      it('v2 fails decrypt for large disk file if incrementalMac is wrong', async () => {
+        const sourcePath = join(tempDir, 'random');
+        const data = getRandomBytes(5 * 1024 * 1024);
+        const plaintextHash = sha256(data);
+        writeFileSync(sourcePath, data);
+        try {
+          await assert.isRejected(
+            testV2RoundTripData({
+              path: sourcePath,
+              data,
+              plaintextHash,
+              modifyIncrementalMac: true,
+            }),
+            /Corrupted/
+          );
+        } finally {
+          unlinkSync(sourcePath);
+        }
+      });
 
       it('v2 roundtrips large file from memory', async () => {
         // Get sufficient large data to have more than 64kb of padding and
@@ -785,6 +822,7 @@ describe('Crypto', () => {
             plaintext: { data: FILE_CONTENTS },
             getAbsoluteAttachmentPath:
               window.Signal.Migrations.getAbsoluteAttachmentPath,
+            needIncrementalMac: true,
           });
 
           await testV2RoundTripData({
@@ -826,6 +864,7 @@ describe('Crypto', () => {
           plaintext: { absolutePath: FILE_PATH },
           getAbsoluteAttachmentPath:
             window.Signal.Migrations.getAbsoluteAttachmentPath,
+          needIncrementalMac: false,
         });
         ciphertextPath = window.Signal.Migrations.getAbsoluteAttachmentPath(
           encryptedAttachment.path
@@ -882,6 +921,7 @@ describe('Crypto', () => {
           dangerousIv: { iv: dangerousTestOnlyIv, reason: 'test' },
           getAbsoluteAttachmentPath:
             window.Signal.Migrations.getAbsoluteAttachmentPath,
+          needIncrementalMac: false,
         });
         ciphertextPath = window.Signal.Migrations.getAbsoluteAttachmentPath(
           encryptedAttachmentV2.path
@@ -918,6 +958,7 @@ describe('Crypto', () => {
             plaintext: { absolutePath: plaintextAbsolutePath },
             getAbsoluteAttachmentPath:
               window.Signal.Migrations.getAbsoluteAttachmentPath,
+            needIncrementalMac: true,
           });
           innerCiphertextPath =
             window.Signal.Migrations.getAbsoluteAttachmentPath(
@@ -931,6 +972,7 @@ describe('Crypto', () => {
             dangerousTestOnlySkipPadding: true,
             getAbsoluteAttachmentPath:
               window.Signal.Migrations.getAbsoluteAttachmentPath,
+            needIncrementalMac: false,
           });
 
           outerCiphertextPath =
@@ -969,6 +1011,9 @@ describe('Crypto', () => {
             ...splitKeys(innerKeys),
             size: FILE_CONTENTS.byteLength,
             theirDigest: encryptResult.innerEncryptedAttachment.digest,
+            theirIncrementalMac:
+              encryptResult.innerEncryptedAttachment.incrementalMac,
+            theirChunkSize: encryptResult.innerEncryptedAttachment.chunkSize,
             outerEncryption: splitKeys(outerKeys),
             getAbsoluteAttachmentPath:
               window.Signal.Migrations.getAbsoluteAttachmentPath,
@@ -1025,6 +1070,9 @@ describe('Crypto', () => {
             ...splitKeys(innerKeys),
             size: data.byteLength,
             theirDigest: encryptResult.innerEncryptedAttachment.digest,
+            theirIncrementalMac:
+              encryptResult.innerEncryptedAttachment.incrementalMac,
+            theirChunkSize: encryptResult.innerEncryptedAttachment.chunkSize,
             outerEncryption: splitKeys(outerKeys),
             getAbsoluteAttachmentPath:
               window.Signal.Migrations.getAbsoluteAttachmentPath,
@@ -1075,6 +1123,9 @@ describe('Crypto', () => {
               ...splitKeys(innerKeys),
               size: data.byteLength,
               theirDigest: encryptResult.innerEncryptedAttachment.digest,
+              theirIncrementalMac:
+                encryptResult.innerEncryptedAttachment.incrementalMac,
+              theirChunkSize: encryptResult.innerEncryptedAttachment.chunkSize,
               outerEncryption: {
                 aesKey: splitKeys(outerKeys).aesKey,
                 macKey: splitKeys(innerKeys).macKey, // wrong mac!

ts/test-electron/services/AttachmentBackupManager_test.ts

@@ -107,6 +107,7 @@ describe('AttachmentBackupManager/JobManager', function attachmentBackupManager(
         absolutePath: join(__dirname, '../../../fixtures/cat-gif.mp4'),
       },
       keys: Bytes.fromBase64(LOCAL_ENCRYPTION_KEYS),
+      needIncrementalMac: false,
       sink: createWriteStream(absolutePath),
       getAbsoluteAttachmentPath,
     });

ts/test-electron/util/ensureAttachmentIsReencryptable_test.ts

@@ -40,6 +40,7 @@ describe('utils/ensureAttachmentIsReencryptable', async () => {
       },
       getAbsoluteAttachmentPath:
         window.Signal.Migrations.getAbsoluteAttachmentPath,
+      needIncrementalMac: false,
     });
     digest = encrypted.digest;
     iv = encrypted.iv;