Coverage Report

Created: 2020-03-26 13:53

/src/botan/build/include/botan/hmac_drbg.h
Line
Count
Source (jump to first uncovered line)
1
/*
2
* HMAC_DRBG (SP800-90A)
3
* (C) 2014,2015,2016 Jack Lloyd
4
*
5
* Botan is released under the Simplified BSD License (see license.txt)
6
*/
7
8
#ifndef BOTAN_HMAC_DRBG_H_
9
#define BOTAN_HMAC_DRBG_H_
10
11
#include <botan/stateful_rng.h>
12
#include <botan/mac.h>
13
14
namespace Botan {
15
16
class Entropy_Sources;
17
18
/**
19
* HMAC_DRBG from NIST SP800-90A
20
*/
21
class BOTAN_PUBLIC_API(2,0) HMAC_DRBG final : public Stateful_RNG
22
   {
23
   public:
24
      /**
25
      * Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)
26
      *
27
      * Automatic reseeding is disabled completely, as it has no access to
28
      * any source for seed material.
29
      *
30
      * If a fork is detected, the RNG will be unable to reseed itself
31
      * in response. In this case, an exception will be thrown rather
32
      * than generating duplicated output.
33
      */
34
      explicit HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf);
35
36
      /**
37
      * Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)
38
      *
39
      * Automatic reseeding from @p underlying_rng will take place after
40
      * @p reseed_interval many requests or after a fork was detected.
41
      *
42
      * @param prf MAC to use as a PRF
43
      * @param underlying_rng is a reference to some RNG which will be used
44
      * to perform the periodic reseeding
45
      * @param reseed_interval specifies a limit of how many times
46
      * the RNG will be called before automatic reseeding is performed (max. 2^24)
47
      * @param max_number_of_bytes_per_request requests that are in size higher
48
      * than max_number_of_bytes_per_request are treated as if multiple single
49
      * requests of max_number_of_bytes_per_request size had been made.
50
      * In theory SP 800-90A requires that we reject any request for a DRBG
51
      * output longer than max_number_of_bytes_per_request. To avoid inconveniencing
52
      * the caller who wants an output larger than max_number_of_bytes_per_request,
53
      * instead treat these requests as if multiple requests of
54
      * max_number_of_bytes_per_request size had been made. NIST requires for
55
      * HMAC_DRBG that every implementation set a value no more than 2**19 bits
56
      * (or 64 KiB). Together with @p reseed_interval = 1 you can enforce that for
57
      * example every 512 bit automatic reseeding occurs.
58
      */
59
      HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf,
60
                RandomNumberGenerator& underlying_rng,
61
                size_t reseed_interval = BOTAN_RNG_DEFAULT_RESEED_INTERVAL,
62
                size_t max_number_of_bytes_per_request = 64 * 1024);
63
64
      /**
65
      * Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)
66
      *
67
      * Automatic reseeding from @p entropy_sources will take place after
68
      * @p reseed_interval many requests or after a fork was detected.
69
      *
70
      * @param prf MAC to use as a PRF
71
      * @param entropy_sources will be polled to perform reseeding periodically
72
      * @param reseed_interval specifies a limit of how many times
73
      * the RNG will be called before automatic reseeding is performed (max. 2^24)
74
      * @param max_number_of_bytes_per_request requests that are in size higher
75
      * than max_number_of_bytes_per_request are treated as if multiple single
76
      * requests of max_number_of_bytes_per_request size had been made.
77
      * In theory SP 800-90A requires that we reject any request for a DRBG
78
      * output longer than max_number_of_bytes_per_request. To avoid inconveniencing
79
      * the caller who wants an output larger than max_number_of_bytes_per_request,
80
      * instead treat these requests as if multiple requests of
81
      * max_number_of_bytes_per_request size had been made. NIST requires for
82
      * HMAC_DRBG that every implementation set a value no more than 2**19 bits
83
      * (or 64 KiB). Together with @p reseed_interval = 1 you can enforce that for
84
      * example every 512 bit automatic reseeding occurs.
85
      */
86
      HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf,
87
                Entropy_Sources& entropy_sources,
88
                size_t reseed_interval = BOTAN_RNG_DEFAULT_RESEED_INTERVAL,
89
                size_t max_number_of_bytes_per_request = 64 * 1024);
90
91
      /**
92
      * Initialize an HMAC_DRBG instance with the given MAC as PRF (normally HMAC)
93
      *
94
      * Automatic reseeding from @p underlying_rng and @p entropy_sources
95
      * will take place after @p reseed_interval many requests or after
96
      * a fork was detected.
97
      *
98
      * @param prf MAC to use as a PRF
99
      * @param underlying_rng is a reference to some RNG which will be used
100
      * to perform the periodic reseeding
101
      * @param entropy_sources will be polled to perform reseeding periodically
102
      * @param reseed_interval specifies a limit of how many times
103
      * the RNG will be called before automatic reseeding is performed (max. 2^24)
104
      * @param max_number_of_bytes_per_request requests that are in size higher
105
      * than max_number_of_bytes_per_request are treated as if multiple single
106
      * requests of max_number_of_bytes_per_request size had been made.
107
      * In theory SP 800-90A requires that we reject any request for a DRBG
108
      * output longer than max_number_of_bytes_per_request. To avoid inconveniencing
109
      * the caller who wants an output larger than max_number_of_bytes_per_request,
110
      * instead treat these requests as if multiple requests of
111
      * max_number_of_bytes_per_request size had been made. NIST requires for
112
      * HMAC_DRBG that every implementation set a value no more than 2**19 bits
113
      * (or 64 KiB). Together with @p reseed_interval = 1 you can enforce that for
114
      * example every 512 bit automatic reseeding occurs.
115
      */
116
      HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf,
117
                RandomNumberGenerator& underlying_rng,
118
                Entropy_Sources& entropy_sources,
119
                size_t reseed_interval = BOTAN_RNG_DEFAULT_RESEED_INTERVAL,
120
                size_t max_number_of_bytes_per_request = 64 * 1024);
121
122
      /**
123
      * Constructor taking a string for the hash
124
      */
125
      explicit HMAC_DRBG(const std::string& hmac_hash) :
126
         Stateful_RNG(),
127
         m_mac(MessageAuthenticationCode::create_or_throw("HMAC(" + hmac_hash + ")")),
128
         m_max_number_of_bytes_per_request(64 * 1024)
129
0
         {
130
0
         clear();
131
0
         }
132
133
      std::string name() const override;
134
135
      void clear() override;
136
137
      void randomize(uint8_t output[], size_t output_len) override;
138
139
      void randomize_with_input(uint8_t output[], size_t output_len,
140
                                const uint8_t input[], size_t input_len) override;
141
142
      void add_entropy(const uint8_t input[], size_t input_len) override;
143
144
      size_t security_level() const override;
145
146
      size_t max_number_of_bytes_per_request() const override
147
0
         { return m_max_number_of_bytes_per_request; }
148
149
   private:
150
      void update(const uint8_t input[], size_t input_len);
151
152
      std::unique_ptr<MessageAuthenticationCode> m_mac;
153
      secure_vector<uint8_t> m_V;
154
      const size_t m_max_number_of_bytes_per_request;
155
   };
156
157
}
158
159
#endif