summaryrefslogtreecommitdiffstats
path: root/crypto/hkdf.h
blob: 4306d3f2f650c53db77061441c28598b61c1a31c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
// 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 CRYPTO_HKDF_H_
#define CRYPTO_HKDF_H_

#include <vector>

#include "base/basictypes.h"
#include "base/memory/scoped_ptr.h"
#include "base/string_piece.h"
#include "build/build_config.h"
#include "crypto/crypto_export.h"

namespace crypto {

// HKDF implements the key derivation function specified in RFC 5869 (using
// SHA-256) and outputs key material, as needed by QUIC.
// See https://tools.ietf.org/html/rfc5869 for details.
class CRYPTO_EXPORT HKDF {
 public:
  // |secret|: The input shared secret (or, from RFC 5869, the IKM).
  // |salt|: an (optional) public salt / non-secret random value. While
  // optional, callers are strongly recommended to provide a salt. There is no
  // added security value in making this larger than the SHA-256 block size of
  // 64 bytes.
  // |info|: an (optional) label to distinguish different uses of HKDF. It is
  // optional context and application specific information (can be a zero-length
  // string).
  // |key_bytes_to_generate|: the number of bytes of key material to generate.
  // |iv_bytes_to_generate|: the number of bytes of IV to generate.
  HKDF(const base::StringPiece& secret,
       const base::StringPiece& salt,
       const base::StringPiece& info,
       size_t key_bytes_to_generate,
       size_t iv_bytes_to_generate);
  virtual ~HKDF();

  base::StringPiece client_write_key() const {
    return client_write_key_;
  }
  base::StringPiece client_write_iv() const {
    return client_write_iv_;
  }
  base::StringPiece server_write_key() const {
    return server_write_key_;
  }
  base::StringPiece server_write_iv() const {
    return server_write_iv_;
  }

 private:
  std::vector<uint8> output_;

  base::StringPiece client_write_key_;
  base::StringPiece server_write_key_;
  base::StringPiece client_write_iv_;
  base::StringPiece server_write_iv_;
};

}  // namespace crypto

#endif  // CRYPTO_HKDF_H_