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      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   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