Initial implementation of music manager private API.

chrome/browser/extensions/api/music_manager_private/device_id.cc

+// Copyright 2013 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.
+
+#include "chrome/browser/extensions/api/music_manager_private/device_id.h"
+
+#include "base/base64.h"
+#include "base/file_util.h"
+#include "base/files/file_path.h"
+#include "base/logging.h"
+#if defined(OS_CHROMEOS)
+#include "chromeos/cryptohome/cryptohome_library.h"
+#endif
+#include "crypto/hmac.h"
+#if defined(ENABLE_RLZ)
+#include "rlz/lib/machine_id.h"
+#endif
+
+namespace {
+
+// Return a unique identifier for the machine/device. Currently, this is only
+// supported on Windows (with RLZ enabled) and ChromeOS.
+std::string GetMachineID() {
+#if defined(OS_WIN) && defined(ENABLE_RLZ)
+  std::string result;
+  rlz_lib::GetMachineId(&result);
+  return result;
+#elif defined(OS_CHROMEOS)
+  chromeos::CryptohomeLibrary* c_home = chromeos::CryptohomeLibrary::Get();
+  return c_home->GetSystemSalt();
+#else
+  // Not implemented for other platforms.
+  return "";
+#endif
+}
+
+// Compute HMAC-SHA256(|key|, |text|) as a string.
+bool ComputeHmacSha256(const std::string& key,
+                       const std::string& text,
+                       std::string* signature_return) {
+  crypto::HMAC hmac(crypto::HMAC::SHA256);
+  const size_t digest_length = hmac.DigestLength();
+  std::vector<uint8> digest(digest_length);
+  bool result = hmac.Init(key) &&
+      hmac.Sign(text, &digest[0], digest.size()) &&
+      base::Base64Encode(std::string(reinterpret_cast<char*>(&digest[0]),
+                                     digest.size()),
+                         signature_return);
+  return result;
+}
+
+}
+
+namespace device_id {
+
+std::string GetDeviceID(const std::string& salt) {
+  CHECK(!salt.empty());
+  std::string machine_id = GetMachineID();
+  if (machine_id.empty()) {
+    DLOG(WARNING) << "API is not supported on current platform.";
+    return "";
+  }
+
+  std::string device_id;
+  if (!ComputeHmacSha256(machine_id, salt, &device_id)) {
+    DLOG(ERROR) << "Error while computing HMAC-SHA256 of device id.";
+    return "";
+  }
+  return device_id;
+}
+
+}  // namespace device_id