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 QUICHE_QUIC_CORE_CRYPTO_P256_KEY_EXCHANGE_H_ 6 #define QUICHE_QUIC_CORE_CRYPTO_P256_KEY_EXCHANGE_H_ 7 8 #include <cstdint> 9 #include <string> 10 11 #include "absl/strings/string_view.h" 12 #include "openssl/base.h" 13 #include "quiche/quic/core/crypto/key_exchange.h" 14 #include "quiche/quic/platform/api/quic_export.h" 15 16 namespace quic { 17 18 // P256KeyExchange implements a SynchronousKeyExchange using elliptic-curve 19 // Diffie-Hellman on NIST P-256. 20 class QUICHE_EXPORT P256KeyExchange : public SynchronousKeyExchange { 21 public: 22 ~P256KeyExchange() override; 23 24 // New generates a private key and then creates new key-exchange object. 25 static std::unique_ptr<P256KeyExchange> New(); 26 27 // New creates a new key-exchange object from a private key. If |private_key| 28 // is invalid, nullptr is returned. 29 static std::unique_ptr<P256KeyExchange> New(absl::string_view private_key); 30 31 // NewPrivateKey returns a private key, suitable for passing to |New|. 32 // If |NewPrivateKey| can't generate a private key, it returns an empty 33 // string. 34 static std::string NewPrivateKey(); 35 36 // SynchronousKeyExchange interface. 37 bool CalculateSharedKeySync(absl::string_view peer_public_value, 38 std::string* shared_key) const override; 39 absl::string_view public_value() const override; type()40 QuicTag type() const override { return kP256; } 41 42 private: 43 enum { 44 // A P-256 field element consists of 32 bytes. 45 kP256FieldBytes = 32, 46 // A P-256 point in uncompressed form consists of 0x04 (to denote 47 // that the point is uncompressed) followed by two, 32-byte field 48 // elements. 49 kUncompressedP256PointBytes = 1 + 2 * kP256FieldBytes, 50 // The first byte in an uncompressed P-256 point. 51 kUncompressedECPointForm = 0x04, 52 }; 53 54 // P256KeyExchange wraps |private_key|, and expects |public_key| consists of 55 // |kUncompressedP256PointBytes| bytes. 56 P256KeyExchange(bssl::UniquePtr<EC_KEY> private_key, 57 const uint8_t* public_key); 58 P256KeyExchange(const P256KeyExchange&) = delete; 59 P256KeyExchange& operator=(const P256KeyExchange&) = delete; 60 61 bssl::UniquePtr<EC_KEY> private_key_; 62 // The public key stored as an uncompressed P-256 point. 63 uint8_t public_key_[kUncompressedP256PointBytes]; 64 }; 65 66 } // namespace quic 67 68 #endif // QUICHE_QUIC_CORE_CRYPTO_P256_KEY_EXCHANGE_H_ 69