Botan  2.12.1
Crypto and TLS for C++11
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 
14 namespace Botan {
15 
16 /*
17 PGP stores the iteration count as a single byte
18 Thus it can only actually take on one of 256 values, based on the
19 formula in RFC 4880 section 3.6.1.3
20 */
21 static 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 
56 uint8_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 
69 size_t RFC4880_decode_count(uint8_t iter)
70  {
71  return OPENPGP_S2K_ITERS[iter];
72  }
73 
74 namespace {
75 
76 void 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 
132 size_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 
154 std::string RFC4880_S2K_Family::name() const
155  {
156  return "OpenPGP-S2K(" + m_hash->name() + ")";
157  }
158 
159 std::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 
183 std::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 
188 std::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 
193 std::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 
204 std::string RFC4880_S2K::to_string() const
205  {
206  return "OpenPGP-S2K(" + m_hash->name() + "," + std::to_string(m_iterations) + ")";
207  }
208 
209 void 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 }
std::unique_ptr< PasswordHash > default_params() const override
Definition: pgp_s2k.cpp:188
std::unique_ptr< PasswordHash > from_iterations(size_t iter) const override
Definition: pgp_s2k.cpp:193
std::unique_ptr< PasswordHash > tune(size_t output_len, std::chrono::milliseconds msec, size_t max_mem) const override
Definition: pgp_s2k.cpp:159
const uint8_t * cast_char_ptr_to_uint8(const char *s)
Definition: mem_ops.h:164
std::string to_string(const BER_Object &obj)
Definition: asn1_obj.cpp:213
size_t RFC4880_decode_count(uint8_t iter)
Definition: pgp_s2k.cpp:69
double bytes_per_second() const
Definition: timer.h:139
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
size_t salt_len
Definition: x509_obj.cpp:25
RFC4880_S2K(HashFunction *hash, size_t iterations)
Definition: pgp_s2k.cpp:198
void copy_mem(T *out, const T *in, size_t n)
Definition: mem_ops.h:122
Definition: alg_id.cpp:13
size_t RFC4880_round_iterations(size_t iterations)
Definition: pgp_s2k.h:40
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::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
MechanismType hash
std::string to_string() const override
Definition: pgp_s2k.cpp:204
void run_until_elapsed(std::chrono::milliseconds msec, F f)
Definition: timer.h:82
uint8_t RFC4880_encode_count(size_t desired_iterations)
Definition: pgp_s2k.cpp:56