media_device_id.cc revision 1e9bf3e0803691d0a228da41fc608347b6db4340 
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 GURL& security_origin,
14                                    const std::string& raw_unique_id) {
15  DCHECK(security_origin.is_valid());
16  DCHECK(!raw_unique_id.empty());
17  crypto::HMAC hmac(crypto::HMAC::SHA256);
18  const size_t digest_length = hmac.DigestLength();
19  std::vector<uint8> digest(digest_length);
20  bool result = hmac.Init(security_origin.spec()) &&
21      hmac.Sign(raw_unique_id, &digest[0], digest.size());
22  DCHECK(result);
23  return StringToLowerASCII(base::HexEncode(&digest[0], digest.size()));
24}
25
26bool DoesMediaDeviceIDMatchHMAC(const GURL& security_origin,
27                                const std::string& device_guid,
28                                const std::string& raw_unique_id) {
29  DCHECK(security_origin.is_valid());
30  DCHECK(!raw_unique_id.empty());
31  std::string guid_from_raw_device_id =
32      GetHMACForMediaDeviceID(security_origin, raw_unique_id);
33  return guid_from_raw_device_id == device_guid;
34}
35
36}  // namespace content
37