payload_signer.h revision f9cb98c0cacccca803db48502c7bd461d04cb6b0 
1// Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef UPDATE_ENGINE_PAYLOAD_GENERATOR_PAYLOAD_SIGNER_H_
6#define UPDATE_ENGINE_PAYLOAD_GENERATOR_PAYLOAD_SIGNER_H_
7
8#include <string>
9#include <vector>
10
11#include <base/macros.h>
12
13#include "update_engine/update_metadata.pb.h"
14
15// This class encapsulates methods used for payload signing.
16// See update_metadata.proto for more info.
17
18namespace chromeos_update_engine {
19
20class PayloadSigner {
21 public:
22  // Given a raw |hash| and a private key in |private_key_path| calculates the
23  // raw signature in |out_signature|. Returns true on success, false otherwise.
24  static bool SignHash(const std::vector<char>& hash,
25                       const std::string& private_key_path,
26                       std::vector<char>* out_signature);
27
28  // Given an unsigned payload in |unsigned_payload_path| and private keys in
29  // |private_key_path|, calculates the signature blob into
30  // |out_signature_blob|. Note that the payload must already have an updated
31  // manifest that includes the dummy signature op. Returns true on success,
32  // false otherwise.
33  static bool SignPayload(const std::string& unsigned_payload_path,
34                          const std::vector<std::string>& private_key_paths,
35                          std::vector<char>* out_signature_blob);
36
37  // Returns the length of out_signature_blob that will result in a call
38  // to SignPayload with the given private keys. Returns true on success.
39  static bool SignatureBlobLength(
40      const std::vector<std::string>& private_key_paths,
41      uint64_t* out_length);
42
43  // This is a helper method for HashPayloadforSigning and
44  // HashMetadataForSigning. It loads the payload into memory, and inserts
45  // signature placeholders if Signatures aren't already present.
46  static bool PrepPayloadForHashing(
47        const std::string& payload_path,
48        const std::vector<int>& signature_sizes,
49        std::vector<char>* payload_out,
50        uint64_t* metadata_size_out,
51        uint64_t* signatures_offset_out);
52
53  // Given an unsigned payload in |payload_path|,
54  // this method does two things:
55  // 1. Uses PrepPayloadForHashing to inserts placeholder signature operations
56  //    to make the manifest match what the final signed payload will look
57  //    like based on |signatures_sizes|, if needed.
58  // 2. It calculates the raw SHA256 hash of the payload in |payload_path|
59  //    (except signatures) and returns the result in |out_hash_data|.
60  //
61  // The dummy signatures are not preserved or written to disk.
62  static bool HashPayloadForSigning(const std::string& payload_path,
63                                    const std::vector<int>& signature_sizes,
64                                    std::vector<char>* out_hash_data);
65
66  // Given an unsigned payload in |payload_path|,
67  // this method does two things:
68  // 1. Uses PrepPayloadForHashing to inserts placeholder signature operations
69  //    to make the manifest match what the final signed payload will look
70  //    like based on |signatures_sizes|, if needed.
71  // 2. It calculates the raw SHA256 hash of the metadata from the payload in
72  //    |payload_path| (except signatures) and returns the result in
73  //    |out_metadata_hash|.
74  //
75  // The dummy signatures are not preserved or written to disk.
76  static bool HashMetadataForSigning(const std::string& payload_path,
77                                     const std::vector<int>& signature_sizes,
78                                     std::vector<char>* out_metadata_hash);
79
80  // Given an unsigned payload in |payload_path| (with no dummy signature op)
81  // and the raw |signatures| updates the payload to include the signature thus
82  // turning it into a signed payload. The new payload is stored in
83  // |signed_payload_path|. |payload_path| and |signed_payload_path| can point
84  // to the same file. Populates |out_metadata_size| with the size of the
85  // metadata after adding the signature operation in the manifest.Returns true
86  // on success, false otherwise.
87  static bool AddSignatureToPayload(
88      const std::string& payload_path,
89      const std::vector<std::vector<char>>& signatures,
90      const std::string& signed_payload_path,
91      uint64_t* out_metadata_size);
92
93  // Computes the SHA256 hash of the first metadata_size bytes of |metadata|
94  // and signs the hash with the given private_key_path and writes the signed
95  // hash in |out_signature|. Returns true if successful or false if there was
96  // any error in the computations.
97  static bool GetMetadataSignature(const char* const metadata,
98                                   size_t metadata_size,
99                                   const std::string& private_key_path,
100                                   std::string* out_signature);
101
102 private:
103  // This should never be constructed
104  DISALLOW_IMPLICIT_CONSTRUCTORS(PayloadSigner);
105};
106
107}  // namespace chromeos_update_engine
108
109#endif  // UPDATE_ENGINE_PAYLOAD_GENERATOR_PAYLOAD_SIGNER_H_
110