Adjust bloat patch to only write zero bytes

Previously, the bloat patch would still partially leak actual file contents. This commit fixes that so it only writes nonsense that is useless to an attacker.

bin/asarmor.ts

@@ -13,7 +13,7 @@ program
   .option('-r, --restore', 'restore backup')
   .option(
     '-bl, --bloat [gigabytes]',
-    'add huge random files to disk on extraction attempt'
+    'fill the drive with useless data on extraction attempt'
   )
   .option('-e, --encrypt <src>', 'encrypt file contents')
   .option('-k, --key <file path>', 'key file to use for encryption')

src/patch.ts

@@ -3,14 +3,14 @@ import { Archive, FileEntries } from './asar';
 
 export type Patch = Partial<Archive>;
 
+const CHUNK_SIZE = 1024 * 1024 * 1024;
+
 /**
- * Adds a bunch of random files with large sizes to the archive.
- *
- * This patch will result in huge files being written to disk upon extraction with `asar extract`, so use at your own risk AND responsibility!
+ * Upon extraction with `asar extract`, this patch will write empty zero-filled (0 bytes) files of the target size in chunks of `1 GB` to disk. Use at your own risk AND responsibility!
  *
- * Defaults to `100 GB` of bloat.
+ * Defaults to `100 GB`.
  */
-export function createBloatPatch(gigabytes = 10): Patch {
+export function createBloatPatch(gigabytes = 100): Patch {
   const files: FileEntries = {};
 
   for (let i = 0; i < gigabytes; i++) {
@@ -19,7 +19,9 @@ export function createBloatPatch(gigabytes = 10): Patch {
     while (Object.keys(files).indexOf(filename) > -1)
       filename = randomBytes(30).toString('hex');
 
-    files[filename] = { offset: '0', size: 1 * 1024 * 1024 * 1024 };
+    const offset = Number.MAX_SAFE_INTEGER - CHUNK_SIZE;
+
+    files[filename] = { offset: offset.toString(), size: CHUNK_SIZE };
   }
 
   return {