Implement QUIC key extraction.

net/quic/crypto/crypto_handshake.h

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_QUIC_CRYPTO_CRYPTO_HANDSHAKE_H_
 #define NET_QUIC_CRYPTO_CRYPTO_HANDSHAKE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 82 matching lines @@
 // Parameters negotiated by the crypto handshake.
 struct NET_EXPORT_PRIVATE QuicCryptoNegotiatedParameters {
   // Initializes the members to 0 or empty values.
   QuicCryptoNegotiatedParameters();
   ~QuicCryptoNegotiatedParameters();
 
   QuicTag key_exchange;
   QuicTag aead;
   std::string initial_premaster_secret;
   std::string forward_secure_premaster_secret;
+  // subkey_secret is used as the PRK input to the HKDF used for key extraction.
+  std::string subkey_secret;
   CrypterPair initial_crypters;
   CrypterPair forward_secure_crypters;
   // Normalized SNI: converted to lower case and trailing '.' removed.
   std::string sni;
   std::string client_nonce;
   std::string server_nonce;
   // hkdf_input_suffix contains the HKDF input following the label: the
   // ConnectionId, client hello and server config. This is only populated in the
   // client because only the client needs to derive the forward secure keys at a
   // later time from the initial keys.
@@ skipping 39 matching lines @@
 
   const CommonCertSets* common_cert_sets;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(QuicCryptoConfig);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_CRYPTO_CRYPTO_HANDSHAKE_H_