Botan 2.19.1
Crypto and TLS for C&
pgp_s2k.cpp
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1/*
2* OpenPGP S2K
3* (C) 1999-2007,2017 Jack Lloyd
4* (C) 2018 Ribose Inc
5*
6* Distributed under the terms of the Botan license
7*/
8
9#include <botan/pgp_s2k.h>
10#include <botan/exceptn.h>
11#include <botan/internal/timer.h>
12#include <algorithm>
13
14namespace Botan {
15
16/*
17PGP stores the iteration count as a single byte
18Thus it can only actually take on one of 256 values, based on the
19formula in RFC 4880 section 3.6.1.3
20*/
21static const uint32_t OPENPGP_S2K_ITERS[256] = {
22 1024, 1088, 1152, 1216, 1280, 1344, 1408, 1472, 1536, 1600,
23 1664, 1728, 1792, 1856, 1920, 1984, 2048, 2176, 2304, 2432,
24 2560, 2688, 2816, 2944, 3072, 3200, 3328, 3456, 3584, 3712,
25 3840, 3968, 4096, 4352, 4608, 4864, 5120, 5376, 5632, 5888,
26 6144, 6400, 6656, 6912, 7168, 7424, 7680, 7936, 8192, 8704,
27 9216, 9728, 10240, 10752, 11264, 11776, 12288, 12800, 13312,
28 13824, 14336, 14848, 15360, 15872, 16384, 17408, 18432, 19456,
29 20480, 21504, 22528, 23552, 24576, 25600, 26624, 27648, 28672,
30 29696, 30720, 31744, 32768, 34816, 36864, 38912, 40960, 43008,
31 45056, 47104, 49152, 51200, 53248, 55296, 57344, 59392, 61440,
32 63488, 65536, 69632, 73728, 77824, 81920, 86016, 90112, 94208,
33 98304, 102400, 106496, 110592, 114688, 118784, 122880, 126976,
34 131072, 139264, 147456, 155648, 163840, 172032, 180224, 188416,
35 196608, 204800, 212992, 221184, 229376, 237568, 245760, 253952,
36 262144, 278528, 294912, 311296, 327680, 344064, 360448, 376832,
37 393216, 409600, 425984, 442368, 458752, 475136, 491520, 507904,
38 524288, 557056, 589824, 622592, 655360, 688128, 720896, 753664,
39 786432, 819200, 851968, 884736, 917504, 950272, 983040, 1015808,
40 1048576, 1114112, 1179648, 1245184, 1310720, 1376256, 1441792,
41 1507328, 1572864, 1638400, 1703936, 1769472, 1835008, 1900544,
42 1966080, 2031616, 2097152, 2228224, 2359296, 2490368, 2621440,
43 2752512, 2883584, 3014656, 3145728, 3276800, 3407872, 3538944,
44 3670016, 3801088, 3932160, 4063232, 4194304, 4456448, 4718592,
45 4980736, 5242880, 5505024, 5767168, 6029312, 6291456, 6553600,
46 6815744, 7077888, 7340032, 7602176, 7864320, 8126464, 8388608,
47 8912896, 9437184, 9961472, 10485760, 11010048, 11534336,
48 12058624, 12582912, 13107200, 13631488, 14155776, 14680064,
49 15204352, 15728640, 16252928, 16777216, 17825792, 18874368,
50 19922944, 20971520, 22020096, 23068672, 24117248, 25165824,
51 26214400, 27262976, 28311552, 29360128, 30408704, 31457280,
52 32505856, 33554432, 35651584, 37748736, 39845888, 41943040,
53 44040192, 46137344, 48234496, 50331648, 52428800, 54525952,
54 56623104, 58720256, 60817408, 62914560, 65011712 };
55
56uint8_t RFC4880_encode_count(size_t desired_iterations)
57 {
58 if(desired_iterations <= OPENPGP_S2K_ITERS[0])
59 return 0;
60
61 if(desired_iterations >= OPENPGP_S2K_ITERS[255])
62 return 255;
63
64 auto i = std::lower_bound(OPENPGP_S2K_ITERS, OPENPGP_S2K_ITERS + 256, desired_iterations);
65
66 return static_cast<uint8_t>(i - OPENPGP_S2K_ITERS);
67 }
68
69size_t RFC4880_decode_count(uint8_t iter)
70 {
71 return OPENPGP_S2K_ITERS[iter];
72 }
73
74namespace {
75
76void pgp_s2k(HashFunction& hash,
77 uint8_t output_buf[], size_t output_len,
78 const char* password, const size_t password_size,
79 const uint8_t salt[], size_t salt_len,
80 size_t iterations)
81 {
82 if(iterations > 1 && salt_len == 0)
83 throw Invalid_Argument("OpenPGP S2K requires a salt in iterated mode");
84
85 secure_vector<uint8_t> input_buf(salt_len + password_size);
86 if(salt_len > 0)
87 {
88 copy_mem(&input_buf[0], salt, salt_len);
89 }
90 if(password_size > 0)
91 {
92 copy_mem(&input_buf[salt_len],
93 cast_char_ptr_to_uint8(password),
94 password_size);
95 }
96
97 secure_vector<uint8_t> hash_buf(hash.output_length());
98
99 size_t pass = 0;
100 size_t generated = 0;
101
102 while(generated != output_len)
103 {
104 const size_t output_this_pass =
105 std::min(hash_buf.size(), output_len - generated);
106
107 // Preload some number of zero bytes (empty first iteration)
108 std::vector<uint8_t> zero_padding(pass);
109 hash.update(zero_padding);
110
111 // The input is always fully processed even if iterations is very small
112 if(input_buf.empty() == false)
113 {
114 size_t left = std::max(iterations, input_buf.size());
115 while(left > 0)
116 {
117 const size_t input_to_take = std::min(left, input_buf.size());
118 hash.update(input_buf.data(), input_to_take);
119 left -= input_to_take;
120 }
121 }
122
123 hash.final(hash_buf.data());
124 copy_mem(output_buf + generated, hash_buf.data(), output_this_pass);
125 generated += output_this_pass;
126 ++pass;
127 }
128 }
129
130}
131
132size_t OpenPGP_S2K::pbkdf(uint8_t output_buf[], size_t output_len,
133 const std::string& password,
134 const uint8_t salt[], size_t salt_len,
135 size_t iterations,
136 std::chrono::milliseconds msec) const
137 {
138 std::unique_ptr<PasswordHash> pwdhash;
139
140 if(iterations == 0)
141 {
142 RFC4880_S2K_Family s2k_params(m_hash->clone());
143 iterations = s2k_params.tune(output_len, msec, 0)->iterations();
144 }
145
146 pgp_s2k(*m_hash, output_buf, output_len,
147 password.c_str(), password.size(),
148 salt, salt_len,
149 iterations);
150
151 return iterations;
152 }
153
154std::string RFC4880_S2K_Family::name() const
155 {
156 return "OpenPGP-S2K(" + m_hash->name() + ")";
157 }
158
159std::unique_ptr<PasswordHash> RFC4880_S2K_Family::tune(size_t output_len, std::chrono::milliseconds msec, size_t) const
160 {
161 const auto tune_time = BOTAN_PBKDF_TUNING_TIME;
162
163 const size_t buf_size = 1024;
164 std::vector<uint8_t> buffer(buf_size);
165
166 Timer timer("RFC4880_S2K", buf_size);
167 timer.run_until_elapsed(tune_time, [&]() {
168 m_hash->update(buffer);
169 });
170
171 const double hash_bytes_per_second = timer.bytes_per_second();
172 const uint64_t desired_nsec = msec.count() * 1000000;
173
174 const size_t hash_size = m_hash->output_length();
175 const size_t blocks_required = (output_len <= hash_size ? 1 : (output_len + hash_size - 1) / hash_size);
176
177 const double bytes_to_be_hashed = (hash_bytes_per_second * (desired_nsec / 1000000000.0)) / blocks_required;
178 const size_t iterations = RFC4880_round_iterations(static_cast<size_t>(bytes_to_be_hashed));
179
180 return std::unique_ptr<PasswordHash>(new RFC4880_S2K(m_hash->clone(), iterations));
181 }
182
183std::unique_ptr<PasswordHash> RFC4880_S2K_Family::from_params(size_t iter, size_t, size_t) const
184 {
185 return std::unique_ptr<PasswordHash>(new RFC4880_S2K(m_hash->clone(), iter));
186 }
187
188std::unique_ptr<PasswordHash> RFC4880_S2K_Family::default_params() const
189 {
190 return std::unique_ptr<PasswordHash>(new RFC4880_S2K(m_hash->clone(), 50331648));
191 }
192
193std::unique_ptr<PasswordHash> RFC4880_S2K_Family::from_iterations(size_t iter) const
194 {
195 return std::unique_ptr<PasswordHash>(new RFC4880_S2K(m_hash->clone(), iter));
196 }
197
199 m_hash(hash),
200 m_iterations(iterations)
201 {
202 }
203
204std::string RFC4880_S2K::to_string() const
205 {
206 return "OpenPGP-S2K(" + m_hash->name() + "," + std::to_string(m_iterations) + ")";
207 }
208
209void RFC4880_S2K::derive_key(uint8_t out[], size_t out_len,
210 const char* password, const size_t password_len,
211 const uint8_t salt[], size_t salt_len) const
212 {
213 pgp_s2k(*m_hash, out, out_len,
214 password, password_len,
215 salt, salt_len,
216 m_iterations);
217 }
218
219}
size_t pbkdf(uint8_t output_buf[], size_t output_len, const std::string &passphrase, const uint8_t salt[], size_t salt_len, size_t iterations, std::chrono::milliseconds msec) const override
Definition: pgp_s2k.cpp:132
std::unique_ptr< PasswordHash > tune(size_t output_len, std::chrono::milliseconds msec, size_t max_mem) const override
Definition: pgp_s2k.cpp:159
std::unique_ptr< PasswordHash > default_params() const override
Definition: pgp_s2k.cpp:188
std::string name() const override
Definition: pgp_s2k.cpp:154
std::unique_ptr< PasswordHash > from_params(size_t iter, size_t, size_t) const override
Definition: pgp_s2k.cpp:183
std::unique_ptr< PasswordHash > from_iterations(size_t iter) const override
Definition: pgp_s2k.cpp:193
std::string to_string() const override
Definition: pgp_s2k.cpp:204
void derive_key(uint8_t out[], size_t out_len, const char *password, size_t password_len, const uint8_t salt[], size_t salt_len) const override
Definition: pgp_s2k.cpp:209
RFC4880_S2K(HashFunction *hash, size_t iterations)
Definition: pgp_s2k.cpp:198
void run_until_elapsed(std::chrono::milliseconds msec, F f)
Definition: timer.h:82
double bytes_per_second() const
Definition: timer.h:139
std::string to_string(const BER_Object &obj)
Definition: asn1_obj.cpp:213
Definition: alg_id.cpp:13
uint8_t RFC4880_encode_count(size_t desired_iterations)
Definition: pgp_s2k.cpp:56
void copy_mem(T *out, const T *in, size_t n)
Definition: mem_ops.h:133
size_t RFC4880_decode_count(uint8_t iter)
Definition: pgp_s2k.cpp:69
size_t RFC4880_round_iterations(size_t iterations)
Definition: pgp_s2k.h:40
const uint8_t * cast_char_ptr_to_uint8(const char *s)
Definition: mem_ops.h:190
MechanismType hash
size_t salt_len
Definition: x509_obj.cpp:25