net/quic/crypto/quic_encrypter.h

   1 // Copyright (c) 2012 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_QUIC_ENCRYPTER_H_
   6 #define NET_QUIC_CRYPTO_QUIC_ENCRYPTER_H_
   7
   8 #include "net/base/net_export.h"
   9 #include "net/quic/quic_protocol.h"
  10
  11 namespace net {
  12
  13 class NET_EXPORT_PRIVATE QuicEncrypter {
  14  public:
  15   virtual ~QuicEncrypter() {}
  16
  17   static QuicEncrypter* Create(QuicTag algorithm);
  18
  19   // Sets the encryption key. Returns true on success, false on failure.
  20   //
  21   // NOTE: The key is the client_write_key or server_write_key derived from
  22   // the master secret.
  23   virtual bool SetKey(base::StringPiece key) = 0;
  24
  25   // Sets the fixed initial bytes of the nonce. Returns true on success,
  26   // false on failure.
  27   //
  28   // NOTE: The nonce prefix is the client_write_iv or server_write_iv
  29   // derived from the master secret. A 64-bit packet sequence number will
  30   // be appended to form the nonce.
  31   //
  32   //                          <------------ 64 bits ----------->
  33   //   +---------------------+----------------------------------+
  34   //   |    Fixed prefix     |      Packet sequence number      |
  35   //   +---------------------+----------------------------------+
  36   //                          Nonce format
  37   //
  38   // The security of the nonce format requires that QUIC never reuse a
  39   // packet sequence number, even when retransmitting a lost packet.
  40   virtual bool SetNoncePrefix(base::StringPiece nonce_prefix) = 0;
  41
  42   // Encrypt encrypts |plaintext| and writes the ciphertext, plus a MAC over
  43   // both |associated_data| and |plaintext| to |output|, using |nonce| as the
  44   // nonce. |nonce| must be |8+GetNoncePrefixSize()| bytes long and |output|
  45   // must point to a buffer that is at least
  46   // |GetCiphertextSize(plaintext.size()| bytes long.
  47   virtual bool Encrypt(base::StringPiece nonce,
  48                        base::StringPiece associated_data,
  49                        base::StringPiece plaintext,
  50                        unsigned char* output) = 0;
  51
  52   // Returns a newly created QuicData object containing the encrypted
  53   // |plaintext| as well as a MAC over both |plaintext| and |associated_data|,
  54   // or NULL if there is an error. |sequence_number| is appended to the
  55   // |nonce_prefix| value provided in SetNoncePrefix() to form the nonce.
  56   virtual QuicData* EncryptPacket(QuicPacketSequenceNumber sequence_number,
  57                                   base::StringPiece associated_data,
  58                                   base::StringPiece plaintext) = 0;
  59
  60   // GetKeySize() and GetNoncePrefixSize() tell the HKDF class how many bytes
  61   // of key material needs to be derived from the master secret.
  62   // NOTE: the sizes returned by GetKeySize() and GetNoncePrefixSize() are
  63   // also correct for the QuicDecrypter of the same algorithm. So only
  64   // QuicEncrypter has these two methods.
  65
  66   // Returns the size in bytes of a key for the algorithm.
  67   virtual size_t GetKeySize() const = 0;
  68   // Returns the size in bytes of the fixed initial part of the nonce.
  69   virtual size_t GetNoncePrefixSize() const = 0;
  70
  71   // Returns the maximum length of plaintext that can be encrypted
  72   // to ciphertext no larger than |ciphertext_size|.
  73   virtual size_t GetMaxPlaintextSize(size_t ciphertext_size) const = 0;
  74
  75   // Returns the length of the ciphertext that would be generated by encrypting
  76   // to plaintext of size |plaintext_size|.
  77   virtual size_t GetCiphertextSize(size_t plaintext_size) const = 0;
  78
  79   // For use by unit tests only.
  80   virtual base::StringPiece GetKey() const = 0;
  81   virtual base::StringPiece GetNoncePrefix() const = 0;
  82 };
  83
  84 }  // namespace net
  85
  86 #endif  // NET_QUIC_CRYPTO_QUIC_ENCRYPTER_H_