remoting/protocol/authentication_method.cc

   1 // Copyright (c) 2012 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/protocol/authentication_method.h"
   6
   7 #include "base/base64.h"
   8 #include "base/logging.h"
   9 #include "crypto/hmac.h"
  10 #include "remoting/protocol/auth_util.h"
  11
  12 namespace remoting {
  13 namespace protocol {
  14
  15 // static
  16 AuthenticationMethod AuthenticationMethod::Invalid() {
  17   return AuthenticationMethod();
  18 }
  19
  20 // static
  21 AuthenticationMethod AuthenticationMethod::Spake2(HashFunction hash_function) {
  22   return AuthenticationMethod(SPAKE2, hash_function);
  23 }
  24
  25 // static
  26 AuthenticationMethod AuthenticationMethod::Spake2Pair() {
  27   return AuthenticationMethod(SPAKE2_PAIR, HMAC_SHA256);
  28 }
  29
  30 // static
  31 AuthenticationMethod AuthenticationMethod::ThirdParty() {
  32   return AuthenticationMethod(THIRD_PARTY, NONE);
  33 }
  34
  35 // static
  36 AuthenticationMethod AuthenticationMethod::FromString(
  37     const std::string& value) {
  38   if (value == "spake2_pair") {
  39     return Spake2Pair();
  40   } else if (value == "spake2_plain") {
  41     return Spake2(NONE);
  42   } else if (value == "spake2_hmac") {
  43     return Spake2(HMAC_SHA256);
  44   } else if (value == "third_party") {
  45     return ThirdParty();
  46   } else {
  47     return AuthenticationMethod::Invalid();
  48   }
  49 }
  50
  51 // static
  52 std::string AuthenticationMethod::ApplyHashFunction(
  53     HashFunction hash_function,
  54     const std::string& tag,
  55     const std::string& shared_secret) {
  56   switch (hash_function) {
  57     case NONE:
  58       return shared_secret;
  59       break;
  60
  61     case HMAC_SHA256: {
  62       crypto::HMAC response(crypto::HMAC::SHA256);
  63       if (!response.Init(tag)) {
  64         LOG(FATAL) << "HMAC::Init failed";
  65       }
  66
  67       unsigned char out_bytes[kSharedSecretHashLength];
  68       if (!response.Sign(shared_secret, out_bytes, sizeof(out_bytes))) {
  69         LOG(FATAL) << "HMAC::Sign failed";
  70       }
  71
  72       return std::string(out_bytes, out_bytes + sizeof(out_bytes));
  73     }
  74   }
  75
  76   NOTREACHED();
  77   return shared_secret;
  78 }
  79
  80 AuthenticationMethod::AuthenticationMethod()
  81     : type_(INVALID),
  82       hash_function_(NONE) {
  83 }
  84
  85 AuthenticationMethod::AuthenticationMethod(MethodType type,
  86                                            HashFunction hash_function)
  87     : type_(type),
  88       hash_function_(hash_function) {
  89   DCHECK_NE(type_, INVALID);
  90 }
  91
  92 AuthenticationMethod::HashFunction AuthenticationMethod::hash_function() const {
  93   DCHECK(is_valid());
  94   return hash_function_;
  95 }
  96
  97 const std::string AuthenticationMethod::ToString() const {
  98   DCHECK(is_valid());
  99
 100   switch (type_) {
 101     case INVALID:
 102       NOTREACHED();
 103       break;
 104
 105     case SPAKE2_PAIR:
 106       return "spake2_pair";
 107
 108     case SPAKE2:
 109       switch (hash_function_) {
 110         case NONE:
 111           return "spake2_plain";
 112         case HMAC_SHA256:
 113           return "spake2_hmac";
 114       }
 115       break;
 116
 117     case THIRD_PARTY:
 118       return "third_party";
 119   }
 120
 121   return "invalid";
 122 }
 123
 124 bool AuthenticationMethod::operator ==(
 125     const AuthenticationMethod& other) const {
 126   return type_ == other.type_ &&
 127       hash_function_ == other.hash_function_;
 128 }
 129
 130 bool SharedSecretHash::Parse(const std::string& as_string) {
 131   size_t separator = as_string.find(':');
 132   if (separator == std::string::npos)
 133     return false;
 134
 135   std::string function_name = as_string.substr(0, separator);
 136   if (function_name == "plain") {
 137     hash_function = AuthenticationMethod::NONE;
 138   } else if (function_name == "hmac") {
 139     hash_function = AuthenticationMethod::HMAC_SHA256;
 140   } else {
 141     return false;
 142   }
 143
 144   if (!base::Base64Decode(as_string.substr(separator + 1), &value)) {
 145     return false;
 146   }
 147
 148   return true;
 149 }
 150
 151 }  // namespace protocol
 152 }  // namespace remoting