AU: Payload Signer class

update_metadata.proto

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Update file format: A delta update file contains all the deltas needed
 // to update a system from one specific version to another specific
 // version. The update format is represented by this struct pseudocode:
 // struct delta_update_file {
 //   char magic[4] = "CrAU";
-//   uint32 file_format_version = 1;
+//   uint64 file_format_version = 1;
 //   uint64 manifest_size;  // Size of protobuf DeltaArchiveManifest
 //   // The Bzip2 compressed DeltaArchiveManifest
 //   char manifest[];
 //
 //   // Data blobs for files, no specific format. The specific offset
 //   // and length of each data blob is recorded in the DeltaArchiveManifest.
 //   struct {
 //     char data[];
 //   } blobs[];
 //
@@ skipping 52 matching lines @@
 // client.
 
 message Extent {
   optional uint64 start_block = 1;
   optional uint64 num_blocks = 2;
 }
 
 message Signatures {
   message Signature {
     optional uint32 version = 1;
-    optional string data = 2;
+    optional bytes data = 2;
   }
   repeated Signature signatures = 1;
 }
 
 message DeltaArchiveManifest {
   message InstallOperation {
     enum Type {
       REPLACE = 0;  // Replace destination extents w/ attached data
       REPLACE_BZ = 1;  // Replace destination extents w/ attached bzipped data
       MOVE = 2;  // Move source extents to destination extents
@@ skipping 25 matching lines @@
   // (At time of writing) usually 4096
   optional uint32 block_size = 3 [default = 4096];
 
   // If signatures are present, the offset into the blobs, generally
   // tacked onto the end of the file. We use an offset rather than
   // a bool to allow for more flexibility in future file formats.
   // If this is absent, it means signatures aren't supported in this
   // file.
   optional uint64 signatures_offset = 4;
 }