Add option to specify a kernel subkey signing key to firmware signing utility.

utility/include/firmware_utility.h

 // Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef VBOOT_REFERENCE_FIRMWARE_UTILITY_H_
 #define VBOOT_REFERENCE_FIRMWARE_UTILITY_H_
 
 #include <string>
 
 class FirmwareImage;
@@ skipping 41 matching lines @@
 
   FirmwareImage* image_;
   RSAPublicKey* root_key_pub_;
   std::string root_key_file_;
   std::string root_key_pub_file_;
   std::string firmware_key_file_;
   std::string firmware_key_pub_file_;
   std::string subkey_in_file_;  // Existing key signature header.
   std::string in_file_;
   std::string out_file_;
+  std::string kernel_subkey_sign_pub_file_;
   int firmware_key_version_;
   int firmware_sign_algorithm_;
   int firmware_version_;
+  int kernel_subkey_sign_algorithm_;
   bool is_generate_;  // Are we generating a new image?
   bool is_verify_;  // Are we just verifying an already signed image?
   bool is_describe_; // Should we print out description of the image?
   bool is_only_vblock_;  // Should we just output the verification block?
   bool is_subkey_out_;  // Should we just output the subkey header?
 };
 
 }  // namespace vboot_reference
 
 #endif  // VBOOT_REFERENCE_FIRMWARE_UTILITY_H_