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
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
|
/*
* HMAC_DRBG
* (C) 2014,2015,2016 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/hmac_drbg.h>
#include <algorithm>
namespace Botan {
HMAC_DRBG::HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf,
RandomNumberGenerator& underlying_rng,
size_t reseed_interval,
size_t max_number_of_bytes_per_request) :
Stateful_RNG(underlying_rng, reseed_interval),
m_mac(std::move(prf)),
m_max_number_of_bytes_per_request(max_number_of_bytes_per_request)
{
BOTAN_ASSERT_NONNULL(m_mac);
if(m_max_number_of_bytes_per_request == 0 || m_max_number_of_bytes_per_request > 64 * 1024)
{
throw Invalid_Argument("Invalid value for max_number_of_bytes_per_request");
}
clear();
}
HMAC_DRBG::HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf,
RandomNumberGenerator& underlying_rng,
Entropy_Sources& entropy_sources,
size_t reseed_interval,
size_t max_number_of_bytes_per_request ) :
Stateful_RNG(underlying_rng, entropy_sources, reseed_interval),
m_mac(std::move(prf)),
m_max_number_of_bytes_per_request(max_number_of_bytes_per_request)
{
BOTAN_ASSERT_NONNULL(m_mac);
if(m_max_number_of_bytes_per_request == 0 || m_max_number_of_bytes_per_request > 64 * 1024)
{
throw Invalid_Argument("Invalid value for max_number_of_bytes_per_request");
}
clear();
}
HMAC_DRBG::HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf,
Entropy_Sources& entropy_sources,
size_t reseed_interval,
size_t max_number_of_bytes_per_request) :
Stateful_RNG(entropy_sources, reseed_interval),
m_mac(std::move(prf)),
m_max_number_of_bytes_per_request(max_number_of_bytes_per_request)
{
BOTAN_ASSERT_NONNULL(m_mac);
if(m_max_number_of_bytes_per_request == 0 || m_max_number_of_bytes_per_request > 64 * 1024)
{
throw Invalid_Argument("Invalid value for max_number_of_bytes_per_request");
}
clear();
}
HMAC_DRBG::HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf) :
Stateful_RNG(),
m_mac(std::move(prf)),
m_max_number_of_bytes_per_request(64*1024)
{
BOTAN_ASSERT_NONNULL(m_mac);
clear();
}
void HMAC_DRBG::clear()
{
Stateful_RNG::clear();
m_V.resize(m_mac->output_length());
for(size_t i = 0; i != m_V.size(); ++i)
m_V[i] = 0x01;
m_mac->set_key(std::vector<uint8_t>(m_mac->output_length(), 0x00));
}
std::string HMAC_DRBG::name() const
{
return "HMAC_DRBG(" + m_mac->name() + ")";
}
void HMAC_DRBG::randomize(uint8_t output[], size_t output_len)
{
randomize_with_input(output, output_len, nullptr, 0);
}
/*
* HMAC_DRBG generation
* See NIST SP800-90A section 10.1.2.5
*/
void HMAC_DRBG::randomize_with_input(uint8_t output[], size_t output_len,
const uint8_t input[], size_t input_len)
{
while(output_len > 0)
{
size_t this_req = std::min(m_max_number_of_bytes_per_request, output_len);
output_len -= this_req;
reseed_check();
if(input_len > 0)
{
update(input, input_len);
}
while(this_req)
{
const size_t to_copy = std::min(this_req, m_V.size());
m_mac->update(m_V.data(), m_V.size());
m_mac->final(m_V.data());
copy_mem(output, m_V.data(), to_copy);
output += to_copy;
this_req -= to_copy;
}
update(input, input_len);
}
}
/*
* Reset V and the mac key with new values
* See NIST SP800-90A section 10.1.2.2
*/
void HMAC_DRBG::update(const uint8_t input[], size_t input_len)
{
m_mac->update(m_V);
m_mac->update(0x00);
m_mac->update(input, input_len);
m_mac->set_key(m_mac->final());
m_mac->update(m_V.data(), m_V.size());
m_mac->final(m_V.data());
if(input_len > 0)
{
m_mac->update(m_V);
m_mac->update(0x01);
m_mac->update(input, input_len);
m_mac->set_key(m_mac->final());
m_mac->update(m_V.data(), m_V.size());
m_mac->final(m_V.data());
}
}
void HMAC_DRBG::add_entropy(const uint8_t input[], size_t input_len)
{
update(input, input_len);
if(8*input_len >= security_level())
{
reset_reseed_counter();
}
}
size_t HMAC_DRBG::security_level() const
{
// security strength of the hash function
// for pre-image resistance (see NIST SP 800-57)
// SHA-160: 128 bits, SHA-224, SHA-512/224: 192 bits,
// SHA-256, SHA-512/256, SHA-384, SHA-512: >= 256 bits
// NIST SP 800-90A only supports up to 256 bits though
if(m_mac->output_length() < 32)
{
return (m_mac->output_length() - 4) * 8;
}
else
{
return 32 * 8;
}
}
}
|
