net/quic/crypto/p256_key_exchange.h

   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 #ifndef NET_QUIC_CRYPTO_P256_KEY_EXCHANGE_H_
   6 #define NET_QUIC_CRYPTO_P256_KEY_EXCHANGE_H_
   7
   8 #include <string>
   9
  10 #include "base/memory/scoped_ptr.h"
  11 #include "base/strings/string_piece.h"
  12 #include "net/base/net_export.h"
  13 #include "net/quic/crypto/key_exchange.h"
  14
  15 #if defined(USE_OPENSSL)
  16 #include "crypto/openssl_util.h"
  17 #include "crypto/scoped_openssl_types.h"
  18 #else
  19 #include "crypto/ec_private_key.h"
  20 #include "crypto/scoped_nss_types.h"
  21 #endif
  22
  23 namespace net {
  24
  25 // P256KeyExchange implements a KeyExchange using elliptic-curve
  26 // Diffie-Hellman on NIST P-256.
  27 class NET_EXPORT_PRIVATE P256KeyExchange : public KeyExchange {
  28  public:
  29   ~P256KeyExchange() override;
  30
  31   // New creates a new key exchange object from a private key. If
  32   // |private_key| is invalid, nullptr is returned.
  33   static P256KeyExchange* New(base::StringPiece private_key);
  34
  35   // |NewPrivateKey| returns a private key, suitable for passing to |New|.
  36   // If |NewPrivateKey| can't generate a private key, it returns an empty
  37   // string.
  38   static std::string NewPrivateKey();
  39
  40   // KeyExchange interface.
  41   KeyExchange* NewKeyPair(QuicRandom* rand) const override;
  42   bool CalculateSharedKey(const base::StringPiece& peer_public_value,
  43                           std::string* shared_key) const override;
  44   base::StringPiece public_value() const override;
  45   QuicTag tag() const override;
  46
  47  private:
  48   enum {
  49     // A P-256 field element consists of 32 bytes.
  50     kP256FieldBytes = 32,
  51     // A P-256 point in uncompressed form consists of 0x04 (to denote
  52     // that the point is uncompressed) followed by two, 32-byte field
  53     // elements.
  54     kUncompressedP256PointBytes = 1 + 2 * kP256FieldBytes,
  55     // The first byte in an uncompressed P-256 point.
  56     kUncompressedECPointForm = 0x04,
  57   };
  58
  59 #if defined(USE_OPENSSL)
  60   // P256KeyExchange takes ownership of |private_key|, and expects
  61   // |public_key| consists of |kUncompressedP256PointBytes| bytes.
  62   P256KeyExchange(EC_KEY* private_key, const uint8* public_key);
  63
  64   crypto::ScopedEC_KEY private_key_;
  65 #else
  66   // P256KeyExchange takes ownership of |key_pair|, and expects
  67   // |public_key| consists of |kUncompressedP256PointBytes| bytes.
  68   P256KeyExchange(crypto::ECPrivateKey* key_pair, const uint8* public_key);
  69
  70   scoped_ptr<crypto::ECPrivateKey> key_pair_;
  71 #endif
  72   // The public key stored as an uncompressed P-256 point.
  73   uint8 public_key_[kUncompressedP256PointBytes];
  74
  75   DISALLOW_COPY_AND_ASSIGN(P256KeyExchange);
  76 };
  77
  78 }  // namespace net
  79 #endif  // NET_QUIC_CRYPTO_P256_KEY_EXCHANGE_H_