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/quic_protocol.h"
10
11namespace net {
12
13class NET_EXPORT_PRIVATE QuicDecrypter {
14 public:
15  virtual ~QuicDecrypter() {}
16
17  static QuicDecrypter* 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  // Decrypt authenticates |associated_data| and |ciphertext| and then decrypts
43  // |ciphertext| into |output|, using |nonce|. |nonce| must be 8 bytes longer
44  // than the nonce prefix length returned by GetNoncePrefixSize() (of the
45  // encrypter). |output| must be as long as |ciphertext| on entry and, on
46  // successful return, the true length of the plaintext will be written to
47  // |*output_length|.
48  virtual bool Decrypt(base::StringPiece nonce,
49                       base::StringPiece associated_data,
50                       base::StringPiece ciphertext,
51                       unsigned char* output,
52                       size_t* output_length) = 0;
53
54  // Returns a newly created QuicData object containing the decrypted
55  // |ciphertext| or NULL if there is an error. |sequence_number| is
56  // appended to the |nonce_prefix| value provided in SetNoncePrefix()
57  // to form the nonce.
58  // TODO(wtc): add a way for DecryptPacket to report decryption failure due
59  // to non-authentic inputs, as opposed to other reasons for failure.
60  virtual QuicData* DecryptPacket(QuicPacketSequenceNumber sequence_number,
61                                  base::StringPiece associated_data,
62                                  base::StringPiece ciphertext) = 0;
63
64  // For use by unit tests only.
65  virtual base::StringPiece GetKey() const = 0;
66  virtual base::StringPiece GetNoncePrefix() const = 0;
67};
68
69}  // namespace net
70
71#endif  // NET_QUIC_CRYPTO_QUIC_DECRYPTER_H_
72