remoting/host/host_secret.cc

   1 // Copyright (c) 2011 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
   5 #include "remoting/host/host_secret.h"
   6
   7 #include <string>
   8
   9 #include "base/logging.h"
  10 #include "base/rand_util.h"
  11 #include "base/strings/string_number_conversions.h"
  12
  13 namespace remoting {
  14
  15 namespace {
  16
  17 // 5 digits means 100K possible host secrets with uniform distribution, which
  18 // should be enough for short-term passwords, given that we rate-limit guesses
  19 // in the cloud and expire access codes after a small number of attempts.
  20 const int kHostSecretLength = 5;
  21 const char kHostSecretAlphabet[] = "0123456789";
  22
  23 // Generates cryptographically strong random number in the range [0, max).
  24 int CryptoRandomInt(int max) {
  25   uint32 random_int32;
  26   base::RandBytes(&random_int32, sizeof(random_int32));
  27   return random_int32 % max;
  28 }
  29
  30 }  // namespace
  31
  32 std::string GenerateSupportHostSecret() {
  33   std::string result;
  34   int alphabet_size = strlen(kHostSecretAlphabet);
  35   result.resize(kHostSecretLength);
  36   for (int i = 0; i < kHostSecretLength; ++i) {
  37     result[i] = kHostSecretAlphabet[CryptoRandomInt(alphabet_size)];
  38   }
  39   return result;
  40 }
  41
  42 }  // namespace remoting