quic_decrypter.h revision c2e0dbddbe15c98d52c4786dac06cb8952a8ae6d 
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_DECRYPTER_H_
6#define NET_QUIC_CRYPTO_QUIC_DECRYPTER_H_
7
8#include "net/base/net_export.h"
9#include "net/quic/crypto/crypto_protocol.h"
10#include "net/quic/quic_protocol.h"
11
12namespace net {
13
14class NET_EXPORT_PRIVATE QuicDecrypter {
15 public:
16  virtual ~QuicDecrypter() {}
17
18  static QuicDecrypter* Create(CryptoTag algorithm);
19
20  // Sets the encryption key. Returns true on success, false on failure.
21  //
22  // NOTE: The key is the client_write_key or server_write_key derived from
23  // the master secret.
24  virtual bool SetKey(base::StringPiece key) = 0;
25
26  // Sets the fixed initial bytes of the nonce. Returns true on success,
27  // false on failure.
28  //
29  // NOTE: The nonce prefix is the client_write_iv or server_write_iv
30  // derived from the master secret. A 64-bit packet sequence number will
31  // be appended to form the nonce.
32  //
33  //                          <------------ 64 bits ----------->
34  //   +---------------------+----------------------------------+
35  //   |    Fixed prefix     |      Packet sequence number      |
36  //   +---------------------+----------------------------------+
37  //                          Nonce format
38  //
39  // The security of the nonce format requires that QUIC never reuse a
40  // packet sequence number, even when retransmitting a lost packet.
41  virtual bool SetNoncePrefix(base::StringPiece nonce_prefix) = 0;
42
43  // Decrypt authenticates |associated_data| and |ciphertext| and then decrypts
44  // |ciphertext| into |output|, using |nonce|. |nonce| must be 8 bytes longer
45  // than the nonce prefix length returned by GetNoncePrefixSize() (of the
46  // encrypter). |output| must be as long as |ciphertext| on entry and, on
47  // successful return, the true length of the plaintext will be written to
48  // |*output_length|.
49  virtual bool Decrypt(base::StringPiece nonce,
50                       base::StringPiece associated_data,
51                       base::StringPiece ciphertext,
52                       unsigned char* output,
53                       size_t* output_length) = 0;
54
55  // Returns a newly created QuicData object containing the decrypted
56  // |ciphertext| or NULL if there is an error. |sequence_number| is
57  // appended to the |nonce_prefix| value provided in SetNoncePrefix()
58  // to form the nonce.
59  // TODO(wtc): add a way for DecryptPacket to report decryption failure due
60  // to non-authentic inputs, as opposed to other reasons for failure.
61  virtual QuicData* DecryptPacket(QuicPacketSequenceNumber sequence_number,
62                                  base::StringPiece associated_data,
63                                  base::StringPiece ciphertext) = 0;
64
65  // For use by unit tests only.
66  virtual base::StringPiece GetKey() const = 0;
67  virtual base::StringPiece GetNoncePrefix() const = 0;
68};
69
70}  // namespace net
71
72#endif  // NET_QUIC_CRYPTO_QUIC_DECRYPTER_H_
73