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
11namespace net {
12
13class 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_
87