/src/botan/src/lib/rng/hmac_drbg/hmac_drbg.cpp
Line | Count | Source (jump to first uncovered line) |
1 | | /* |
2 | | * HMAC_DRBG |
3 | | * (C) 2014,2015,2016 Jack Lloyd |
4 | | * |
5 | | * Botan is released under the Simplified BSD License (see license.txt) |
6 | | */ |
7 | | |
8 | | #include <botan/hmac_drbg.h> |
9 | | #include <algorithm> |
10 | | |
11 | | namespace Botan { |
12 | | |
13 | | HMAC_DRBG::HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf, |
14 | | RandomNumberGenerator& underlying_rng, |
15 | | size_t reseed_interval, |
16 | | size_t max_number_of_bytes_per_request) : |
17 | | Stateful_RNG(underlying_rng, reseed_interval), |
18 | | m_mac(std::move(prf)), |
19 | | m_max_number_of_bytes_per_request(max_number_of_bytes_per_request) |
20 | 0 | { |
21 | 0 | BOTAN_ASSERT_NONNULL(m_mac); |
22 | 0 |
|
23 | 0 | if(m_max_number_of_bytes_per_request == 0 || m_max_number_of_bytes_per_request > 64 * 1024) |
24 | 0 | { |
25 | 0 | throw Invalid_Argument("Invalid value for max_number_of_bytes_per_request"); |
26 | 0 | } |
27 | 0 | |
28 | 0 | clear(); |
29 | 0 | } |
30 | | |
31 | | HMAC_DRBG::HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf, |
32 | | RandomNumberGenerator& underlying_rng, |
33 | | Entropy_Sources& entropy_sources, |
34 | | size_t reseed_interval, |
35 | | size_t max_number_of_bytes_per_request ) : |
36 | | Stateful_RNG(underlying_rng, entropy_sources, reseed_interval), |
37 | | m_mac(std::move(prf)), |
38 | | m_max_number_of_bytes_per_request(max_number_of_bytes_per_request) |
39 | 0 | { |
40 | 0 | BOTAN_ASSERT_NONNULL(m_mac); |
41 | 0 |
|
42 | 0 | if(m_max_number_of_bytes_per_request == 0 || m_max_number_of_bytes_per_request > 64 * 1024) |
43 | 0 | { |
44 | 0 | throw Invalid_Argument("Invalid value for max_number_of_bytes_per_request"); |
45 | 0 | } |
46 | 0 | |
47 | 0 | clear(); |
48 | 0 | } |
49 | | |
50 | | HMAC_DRBG::HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf, |
51 | | Entropy_Sources& entropy_sources, |
52 | | size_t reseed_interval, |
53 | | size_t max_number_of_bytes_per_request) : |
54 | | Stateful_RNG(entropy_sources, reseed_interval), |
55 | | m_mac(std::move(prf)), |
56 | | m_max_number_of_bytes_per_request(max_number_of_bytes_per_request) |
57 | 0 | { |
58 | 0 | BOTAN_ASSERT_NONNULL(m_mac); |
59 | 0 |
|
60 | 0 | if(m_max_number_of_bytes_per_request == 0 || m_max_number_of_bytes_per_request > 64 * 1024) |
61 | 0 | { |
62 | 0 | throw Invalid_Argument("Invalid value for max_number_of_bytes_per_request"); |
63 | 0 | } |
64 | 0 | |
65 | 0 | clear(); |
66 | 0 | } |
67 | | |
68 | | HMAC_DRBG::HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf) : |
69 | | Stateful_RNG(), |
70 | | m_mac(std::move(prf)), |
71 | | m_max_number_of_bytes_per_request(64*1024) |
72 | 0 | { |
73 | 0 | BOTAN_ASSERT_NONNULL(m_mac); |
74 | 0 | clear(); |
75 | 0 | } |
76 | | |
77 | | void HMAC_DRBG::clear() |
78 | 0 | { |
79 | 0 | Stateful_RNG::clear(); |
80 | 0 |
|
81 | 0 | m_V.resize(m_mac->output_length()); |
82 | 0 | for(size_t i = 0; i != m_V.size(); ++i) |
83 | 0 | m_V[i] = 0x01; |
84 | 0 | m_mac->set_key(std::vector<uint8_t>(m_mac->output_length(), 0x00)); |
85 | 0 | } |
86 | | |
87 | | std::string HMAC_DRBG::name() const |
88 | 0 | { |
89 | 0 | return "HMAC_DRBG(" + m_mac->name() + ")"; |
90 | 0 | } |
91 | | |
92 | | void HMAC_DRBG::randomize(uint8_t output[], size_t output_len) |
93 | 0 | { |
94 | 0 | randomize_with_input(output, output_len, nullptr, 0); |
95 | 0 | } |
96 | | |
97 | | /* |
98 | | * HMAC_DRBG generation |
99 | | * See NIST SP800-90A section 10.1.2.5 |
100 | | */ |
101 | | void HMAC_DRBG::randomize_with_input(uint8_t output[], size_t output_len, |
102 | | const uint8_t input[], size_t input_len) |
103 | 0 | { |
104 | 0 | while(output_len > 0) |
105 | 0 | { |
106 | 0 | size_t this_req = std::min(m_max_number_of_bytes_per_request, output_len); |
107 | 0 | output_len -= this_req; |
108 | 0 |
|
109 | 0 | reseed_check(); |
110 | 0 |
|
111 | 0 | if(input_len > 0) |
112 | 0 | { |
113 | 0 | update(input, input_len); |
114 | 0 | } |
115 | 0 |
|
116 | 0 | while(this_req) |
117 | 0 | { |
118 | 0 | const size_t to_copy = std::min(this_req, m_V.size()); |
119 | 0 | m_mac->update(m_V.data(), m_V.size()); |
120 | 0 | m_mac->final(m_V.data()); |
121 | 0 | copy_mem(output, m_V.data(), to_copy); |
122 | 0 |
|
123 | 0 | output += to_copy; |
124 | 0 | this_req -= to_copy; |
125 | 0 | } |
126 | 0 |
|
127 | 0 | update(input, input_len); |
128 | 0 | } |
129 | 0 |
|
130 | 0 | } |
131 | | |
132 | | /* |
133 | | * Reset V and the mac key with new values |
134 | | * See NIST SP800-90A section 10.1.2.2 |
135 | | */ |
136 | | void HMAC_DRBG::update(const uint8_t input[], size_t input_len) |
137 | 0 | { |
138 | 0 | m_mac->update(m_V); |
139 | 0 | m_mac->update(0x00); |
140 | 0 | m_mac->update(input, input_len); |
141 | 0 | m_mac->set_key(m_mac->final()); |
142 | 0 |
|
143 | 0 | m_mac->update(m_V.data(), m_V.size()); |
144 | 0 | m_mac->final(m_V.data()); |
145 | 0 |
|
146 | 0 | if(input_len > 0) |
147 | 0 | { |
148 | 0 | m_mac->update(m_V); |
149 | 0 | m_mac->update(0x01); |
150 | 0 | m_mac->update(input, input_len); |
151 | 0 | m_mac->set_key(m_mac->final()); |
152 | 0 |
|
153 | 0 | m_mac->update(m_V.data(), m_V.size()); |
154 | 0 | m_mac->final(m_V.data()); |
155 | 0 | } |
156 | 0 | } |
157 | | |
158 | | void HMAC_DRBG::add_entropy(const uint8_t input[], size_t input_len) |
159 | 0 | { |
160 | 0 | update(input, input_len); |
161 | 0 |
|
162 | 0 | if(8*input_len >= security_level()) |
163 | 0 | { |
164 | 0 | reset_reseed_counter(); |
165 | 0 | } |
166 | 0 | } |
167 | | |
168 | | size_t HMAC_DRBG::security_level() const |
169 | 0 | { |
170 | 0 | // security strength of the hash function |
171 | 0 | // for pre-image resistance (see NIST SP 800-57) |
172 | 0 | // SHA-160: 128 bits, SHA-224, SHA-512/224: 192 bits, |
173 | 0 | // SHA-256, SHA-512/256, SHA-384, SHA-512: >= 256 bits |
174 | 0 | // NIST SP 800-90A only supports up to 256 bits though |
175 | 0 | if(m_mac->output_length() < 32) |
176 | 0 | { |
177 | 0 | return (m_mac->output_length() - 4) * 8; |
178 | 0 | } |
179 | 0 | else |
180 | 0 | { |
181 | 0 | return 32 * 8; |
182 | 0 | } |
183 | 0 | } |
184 | | } |