/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 | | namespace { |
14 | | |
15 | | size_t hmac_drbg_security_level(size_t mac_output_length) |
16 | 0 | { |
17 | | // security strength of the hash function |
18 | | // for pre-image resistance (see NIST SP 800-57) |
19 | | // SHA-160: 128 bits |
20 | | // SHA-224, SHA-512/224: 192 bits, |
21 | | // SHA-256, SHA-512/256, SHA-384, SHA-512: >= 256 bits |
22 | | // NIST SP 800-90A only supports up to 256 bits though |
23 | |
|
24 | 0 | if(mac_output_length < 32) |
25 | 0 | { |
26 | 0 | return (mac_output_length - 4) * 8; |
27 | 0 | } |
28 | 0 | else |
29 | 0 | { |
30 | 0 | return 32 * 8; |
31 | 0 | } |
32 | 0 | } |
33 | | |
34 | | void check_limits(size_t reseed_interval, |
35 | | size_t max_number_of_bytes_per_request) |
36 | 0 | { |
37 | | // SP800-90A permits up to 2^48, but it is not usable on 32 bit |
38 | | // platforms, so we only allow up to 2^24, which is still reasonably high |
39 | 0 | if(reseed_interval == 0 || reseed_interval > static_cast<size_t>(1) << 24) |
40 | 0 | { |
41 | 0 | throw Invalid_Argument("Invalid value for reseed_interval"); |
42 | 0 | } |
43 | | |
44 | 0 | if(max_number_of_bytes_per_request == 0 || max_number_of_bytes_per_request > 64 * 1024) |
45 | 0 | { |
46 | 0 | throw Invalid_Argument("Invalid value for max_number_of_bytes_per_request"); |
47 | 0 | } |
48 | 0 | } |
49 | | |
50 | | } |
51 | | |
52 | | HMAC_DRBG::HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf, |
53 | | RandomNumberGenerator& underlying_rng, |
54 | | size_t reseed_interval, |
55 | | size_t max_number_of_bytes_per_request) : |
56 | | Stateful_RNG(underlying_rng, reseed_interval), |
57 | | m_mac(std::move(prf)), |
58 | | m_max_number_of_bytes_per_request(max_number_of_bytes_per_request), |
59 | | m_security_level(hmac_drbg_security_level(m_mac->output_length())) |
60 | 0 | { |
61 | 0 | BOTAN_ASSERT_NONNULL(m_mac); |
62 | |
|
63 | 0 | check_limits(reseed_interval, max_number_of_bytes_per_request); |
64 | |
|
65 | 0 | clear(); |
66 | 0 | } |
67 | | |
68 | | HMAC_DRBG::HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf, |
69 | | RandomNumberGenerator& underlying_rng, |
70 | | Entropy_Sources& entropy_sources, |
71 | | size_t reseed_interval, |
72 | | size_t max_number_of_bytes_per_request) : |
73 | | Stateful_RNG(underlying_rng, entropy_sources, reseed_interval), |
74 | | m_mac(std::move(prf)), |
75 | | m_max_number_of_bytes_per_request(max_number_of_bytes_per_request), |
76 | | m_security_level(hmac_drbg_security_level(m_mac->output_length())) |
77 | 0 | { |
78 | 0 | BOTAN_ASSERT_NONNULL(m_mac); |
79 | |
|
80 | 0 | check_limits(reseed_interval, max_number_of_bytes_per_request); |
81 | |
|
82 | 0 | clear(); |
83 | 0 | } |
84 | | |
85 | | HMAC_DRBG::HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf, |
86 | | Entropy_Sources& entropy_sources, |
87 | | size_t reseed_interval, |
88 | | size_t max_number_of_bytes_per_request) : |
89 | | Stateful_RNG(entropy_sources, reseed_interval), |
90 | | m_mac(std::move(prf)), |
91 | | m_max_number_of_bytes_per_request(max_number_of_bytes_per_request), |
92 | | m_security_level(hmac_drbg_security_level(m_mac->output_length())) |
93 | 0 | { |
94 | 0 | BOTAN_ASSERT_NONNULL(m_mac); |
95 | |
|
96 | 0 | check_limits(reseed_interval, max_number_of_bytes_per_request); |
97 | |
|
98 | 0 | clear(); |
99 | 0 | } |
100 | | |
101 | | HMAC_DRBG::HMAC_DRBG(std::unique_ptr<MessageAuthenticationCode> prf) : |
102 | | Stateful_RNG(), |
103 | | m_mac(std::move(prf)), |
104 | | m_max_number_of_bytes_per_request(64*1024), |
105 | | m_security_level(hmac_drbg_security_level(m_mac->output_length())) |
106 | 0 | { |
107 | 0 | BOTAN_ASSERT_NONNULL(m_mac); |
108 | 0 | clear(); |
109 | 0 | } |
110 | | |
111 | | HMAC_DRBG::HMAC_DRBG(const std::string& hmac_hash) : |
112 | | Stateful_RNG(), |
113 | | m_mac(MessageAuthenticationCode::create_or_throw("HMAC(" + hmac_hash + ")")), |
114 | | m_max_number_of_bytes_per_request(64 * 1024), |
115 | | m_security_level(hmac_drbg_security_level(m_mac->output_length())) |
116 | 0 | { |
117 | 0 | clear(); |
118 | 0 | } |
119 | | |
120 | | void HMAC_DRBG::clear_state() |
121 | 0 | { |
122 | 0 | if(m_V.size() == 0) |
123 | 0 | { |
124 | 0 | const size_t output_length = m_mac->output_length(); |
125 | 0 | m_V.resize(output_length); |
126 | 0 | } |
127 | |
|
128 | 0 | for(size_t i = 0; i != m_V.size(); ++i) |
129 | 0 | m_V[i] = 0x01; |
130 | 0 | m_mac->set_key(std::vector<uint8_t>(m_V.size(), 0x00)); |
131 | 0 | } |
132 | | |
133 | | std::string HMAC_DRBG::name() const |
134 | 0 | { |
135 | 0 | return "HMAC_DRBG(" + m_mac->name() + ")"; |
136 | 0 | } |
137 | | |
138 | | /* |
139 | | * HMAC_DRBG generation |
140 | | * See NIST SP800-90A section 10.1.2.5 |
141 | | */ |
142 | | void HMAC_DRBG::generate_output(uint8_t output[], size_t output_len, |
143 | | const uint8_t input[], size_t input_len) |
144 | 0 | { |
145 | 0 | if(input_len > 0) |
146 | 0 | { |
147 | 0 | update(input, input_len); |
148 | 0 | } |
149 | |
|
150 | 0 | while(output_len > 0) |
151 | 0 | { |
152 | 0 | const size_t to_copy = std::min(output_len, m_V.size()); |
153 | 0 | m_mac->update(m_V.data(), m_V.size()); |
154 | 0 | m_mac->final(m_V.data()); |
155 | 0 | copy_mem(output, m_V.data(), to_copy); |
156 | |
|
157 | 0 | output += to_copy; |
158 | 0 | output_len -= to_copy; |
159 | 0 | } |
160 | |
|
161 | 0 | update(input, input_len); |
162 | 0 | } |
163 | | |
164 | | /* |
165 | | * Reset V and the mac key with new values |
166 | | * See NIST SP800-90A section 10.1.2.2 |
167 | | */ |
168 | | void HMAC_DRBG::update(const uint8_t input[], size_t input_len) |
169 | 0 | { |
170 | 0 | secure_vector<uint8_t> T(m_V.size()); |
171 | 0 | m_mac->update(m_V); |
172 | 0 | m_mac->update(0x00); |
173 | 0 | m_mac->update(input, input_len); |
174 | 0 | m_mac->final(T.data()); |
175 | 0 | m_mac->set_key(T); |
176 | |
|
177 | 0 | m_mac->update(m_V.data(), m_V.size()); |
178 | 0 | m_mac->final(m_V.data()); |
179 | |
|
180 | 0 | if(input_len > 0) |
181 | 0 | { |
182 | 0 | m_mac->update(m_V); |
183 | 0 | m_mac->update(0x01); |
184 | 0 | m_mac->update(input, input_len); |
185 | 0 | m_mac->final(T.data()); |
186 | 0 | m_mac->set_key(T); |
187 | |
|
188 | 0 | m_mac->update(m_V.data(), m_V.size()); |
189 | 0 | m_mac->final(m_V.data()); |
190 | 0 | } |
191 | 0 | } |
192 | | |
193 | | size_t HMAC_DRBG::security_level() const |
194 | 0 | { |
195 | 0 | return m_security_level; |
196 | 0 | } |
197 | | } |