media_device_id.cc revision 5d1f7b1de12d16ceb2c938c56701a3e8bfa558f7 
1// Copyright 2013 The Chromium 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#include "content/public/browser/media_device_id.h"
5
6#include "base/logging.h"
7#include "base/strings/string_number_conversions.h"
8#include "base/strings/string_util.h"
9#include "crypto/hmac.h"
10
11namespace content {
12
13std::string GetHMACForMediaDeviceID(const ResourceContext::SaltCallback& sc,
14                                    const GURL& security_origin,
15                                    const std::string& raw_unique_id) {
16  DCHECK(security_origin.is_valid());
17  DCHECK(!raw_unique_id.empty());
18  crypto::HMAC hmac(crypto::HMAC::SHA256);
19  const size_t digest_length = hmac.DigestLength();
20  std::vector<uint8> digest(digest_length);
21  std::string salt = sc.Run();
22  bool result = hmac.Init(security_origin.spec()) &&
23      hmac.Sign(raw_unique_id + salt, &digest[0], digest.size());
24  DCHECK(result);
25  return StringToLowerASCII(base::HexEncode(&digest[0], digest.size()));
26}
27
28bool DoesMediaDeviceIDMatchHMAC(const ResourceContext::SaltCallback& sc,
29                                const GURL& security_origin,
30                                const std::string& device_guid,
31                                const std::string& raw_unique_id) {
32  DCHECK(security_origin.is_valid());
33  DCHECK(!raw_unique_id.empty());
34  std::string guid_from_raw_device_id =
35      GetHMACForMediaDeviceID(sc, security_origin, raw_unique_id);
36  return guid_from_raw_device_id == device_guid;
37}
38
39}  // namespace content
40