net/quic/crypto/p256_key_exchange_openssl.cc

   1 // Copyright (c) 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
   5 #include "net/quic/crypto/p256_key_exchange.h"
   6
   7 #include <openssl/ec.h>
   8 #include <openssl/ecdh.h>
   9 #include <openssl/evp.h>
  10
  11 #include "base/logging.h"
  12
  13 using base::StringPiece;
  14 using std::string;
  15
  16 namespace net {
  17
  18 P256KeyExchange::P256KeyExchange(EC_KEY* private_key, const uint8* public_key)
  19     : private_key_(private_key) {
  20   memcpy(public_key_, public_key, sizeof(public_key_));
  21 }
  22
  23 P256KeyExchange::~P256KeyExchange() {}
  24
  25 // static
  26 P256KeyExchange* P256KeyExchange::New(StringPiece key) {
  27   if (key.empty()) {
  28     DVLOG(1) << "Private key is empty";
  29     return nullptr;
  30   }
  31
  32   const uint8* keyp = reinterpret_cast<const uint8*>(key.data());
  33   crypto::ScopedEC_KEY private_key(d2i_ECPrivateKey(nullptr, &keyp,
  34                                                     key.size()));
  35   if (!private_key.get() || !EC_KEY_check_key(private_key.get())) {
  36     DVLOG(1) << "Private key is invalid.";
  37     return nullptr;
  38   }
  39
  40   uint8 public_key[kUncompressedP256PointBytes];
  41   if (EC_POINT_point2oct(EC_KEY_get0_group(private_key.get()),
  42                          EC_KEY_get0_public_key(private_key.get()),
  43                          POINT_CONVERSION_UNCOMPRESSED, public_key,
  44                          sizeof(public_key), nullptr) != sizeof(public_key)) {
  45     DVLOG(1) << "Can't get public key.";
  46     return nullptr;
  47   }
  48
  49   return new P256KeyExchange(private_key.release(), public_key);
  50 }
  51
  52 // static
  53 string P256KeyExchange::NewPrivateKey() {
  54   crypto::ScopedEC_KEY key(EC_KEY_new_by_curve_name(NID_X9_62_prime256v1));
  55   if (!key.get() || !EC_KEY_generate_key(key.get())) {
  56     DVLOG(1) << "Can't generate a new private key.";
  57     return string();
  58   }
  59
  60   int key_len = i2d_ECPrivateKey(key.get(), nullptr);
  61   if (key_len <= 0) {
  62     DVLOG(1) << "Can't convert private key to string";
  63     return string();
  64   }
  65   scoped_ptr<uint8[]> private_key(new uint8[key_len]);
  66   uint8* keyp = private_key.get();
  67   if (!i2d_ECPrivateKey(key.get(), &keyp)) {
  68     DVLOG(1) << "Can't convert private key to string.";
  69     return string();
  70   }
  71   return string(reinterpret_cast<char*>(private_key.get()), key_len);
  72 }
  73
  74 KeyExchange* P256KeyExchange::NewKeyPair(QuicRandom* /*rand*/) const {
  75   // TODO(agl): avoid the serialisation/deserialisation in this function.
  76   const string private_value = NewPrivateKey();
  77   return P256KeyExchange::New(private_value);
  78 }
  79
  80 bool P256KeyExchange::CalculateSharedKey(const StringPiece& peer_public_value,
  81                                          string* out_result) const {
  82   if (peer_public_value.size() != kUncompressedP256PointBytes) {
  83     DVLOG(1) << "Peer public value is invalid";
  84     return false;
  85   }
  86
  87   crypto::ScopedEC_POINT point(
  88       EC_POINT_new(EC_KEY_get0_group(private_key_.get())));
  89   if (!point ||
  90       !EC_POINT_oct2point(/* also test if point is on curve */
  91                           EC_KEY_get0_group(private_key_.get()), point.get(),
  92                           reinterpret_cast<const uint8*>(
  93                               peer_public_value.data()),
  94                           peer_public_value.size(), nullptr)) {
  95     DVLOG(1) << "Can't convert peer public value to curve point.";
  96     return false;
  97   }
  98
  99   uint8 result[kP256FieldBytes];
 100   if (ECDH_compute_key(result, sizeof(result), point.get(), private_key_.get(),
 101                        nullptr) != sizeof(result)) {
 102     DVLOG(1) << "Can't compute ECDH shared key.";
 103     return false;
 104   }
 105
 106   out_result->assign(reinterpret_cast<char*>(result), sizeof(result));
 107   return true;
 108 }
 109
 110 StringPiece P256KeyExchange::public_value() const {
 111   return StringPiece(reinterpret_cast<const char*>(public_key_),
 112                      sizeof(public_key_));
 113 }
 114
 115 QuicTag P256KeyExchange::tag() const { return kP256; }
 116
 117 }  // namespace net