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
23namespace net {
24
25// P256KeyExchange implements a KeyExchange using elliptic-curve
26// Diffie-Hellman on NIST P-256.
27class NET_EXPORT_PRIVATE P256KeyExchange : public KeyExchange {
28 public:
29  virtual ~P256KeyExchange();
30
31  // New creates a new key exchange object from a private key. If
32  // |private_key| is invalid, NULL 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  virtual KeyExchange* NewKeyPair(QuicRandom* rand) const OVERRIDE;
42  virtual bool CalculateSharedKey(const base::StringPiece& peer_public_value,
43                                  std::string* shared_key) const OVERRIDE;
44  virtual base::StringPiece public_value() const OVERRIDE;
45  virtual 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_
80
81