22048403227

Committed 16 Feb 2026 02:47AM UTC coverage: 90.036% (-0.008%) from 90.044%

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Merge pull request #5315 from randombit/jack/no-chrono-in-pwdhash

Add PasswordHashFamily::tune_params

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81.19

/src/lib/pbkdf/scrypt/scrypt.cpp

/**
* (C) 2018 Jack Lloyd
* (C) 2018 Ribose Inc
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/scrypt.h>

#include <botan/exceptn.h>
#include <botan/pbkdf2.h>
#include <botan/internal/bit_ops.h>
#include <botan/internal/fmt.h>
#include <botan/internal/loadstor.h>
#include <botan/internal/mem_utils.h>
#include <botan/internal/salsa20.h>
#include <botan/internal/time_utils.h>

namespace Botan {

namespace {

size_t scrypt_memory_usage(size_t N, size_t r, size_t p) {
   return 128 * r * (N + p);
}

}  // namespace

std::string Scrypt_Family::name() const {
   return "Scrypt";
}

std::unique_ptr<PasswordHash> Scrypt_Family::default_params() const {
   return std::make_unique<Scrypt>(32768, 8, 1);
}

std::unique_ptr<PasswordHash> Scrypt_Family::tune_params(size_t /*output_length*/,
                                                         uint64_t desired_msec,
                                                         std::optional<size_t> max_memory,
                                                         uint64_t tuning_msec) const {
   /*
   * Some rough relations between scrypt parameters and runtime.
   * Denote here by stime(N,r,p) the msec it takes to run scrypt.
   *
   * Empirically for smaller sizes:
   * stime(N,8*r,p) / stime(N,r,p) is ~ 6-7
   * stime(N,r,8*p) / stime(N,r,8*p) is ~ 7
   * stime(2*N,r,p) / stime(N,r,p) is ~ 2
   *
   * Compute stime(8192,1,1) as baseline and extrapolate
   */

   // If max_memory is nullopt or zero this becomes zero and is ignored
   const size_t max_memory_bytes = max_memory.value_or(0) * 1024 * 1024;

   // Starting parameters
   size_t N = 8 * 1024;
   size_t r = 1;
   size_t p = 1;

   auto pwdhash = this->from_params(N, r, p);

   const uint64_t measured_time = measure_cost(tuning_msec, [&]() {
      uint8_t output[32] = {0};
      pwdhash->derive_key(output, sizeof(output), "test", 4, nullptr, 0);
   });

   const uint64_t target_nsec = desired_msec * static_cast<uint64_t>(1000000);

   uint64_t est_nsec = measured_time;

   // In below code we invoke scrypt_memory_usage with p == 0 as p contributes
   // (very slightly) to memory consumption, but N is the driving factor.
   // Including p leads to using an N half as large as what the user would expect.

   // First increase r by 8x if possible
   if(max_memory_bytes == 0 || scrypt_memory_usage(N, r * 8, 0) <= max_memory_bytes) {
      if(target_nsec / est_nsec >= 5) {
         r *= 8;
         est_nsec *= 5;
      }
   }

   // Now double N as many times as we can
   while(max_memory_bytes == 0 || scrypt_memory_usage(N * 2, r, 0) <= max_memory_bytes) {
      if(target_nsec / est_nsec >= 2) {
         N *= 2;
         est_nsec *= 2;
      } else {
         break;
      }
   }

   // If we have extra runtime budget, increment p
   if(target_nsec / est_nsec >= 2) {
      p *= std::min<size_t>(1024, static_cast<size_t>(target_nsec / est_nsec));
   }

   return std::make_unique<Scrypt>(N, r, p);
}

std::unique_ptr<PasswordHash> Scrypt_Family::from_params(size_t N, size_t r, size_t p) const {
   return std::make_unique<Scrypt>(N, r, p);
}

std::unique_ptr<PasswordHash> Scrypt_Family::from_iterations(size_t iter) const {
   const size_t r = 8;
   const size_t p = 1;

   size_t N = 8192;

   if(iter > 50000) {
      N = 16384;
   }
   if(iter > 100000) {
      N = 32768;
   }
   if(iter > 150000) {
      N = 65536;
   }

   return std::make_unique<Scrypt>(N, r, p);
}

Scrypt::Scrypt(size_t N, size_t r, size_t p) : m_N(N), m_r(r), m_p(p) {
   if(!is_power_of_2(N)) {
      throw Invalid_Argument("Scrypt N parameter must be a power of 2");
   }

   if(p == 0 || p > 1024) {
      throw Invalid_Argument("Invalid or unsupported scrypt p");
   }
   if(r == 0 || r > 256) {
      throw Invalid_Argument("Invalid or unsupported scrypt r");
   }
   if(N < 1 || N > 4194304) {
      throw Invalid_Argument("Invalid or unsupported scrypt N");
   }
}

std::string Scrypt::to_string() const {
   return fmt("Scrypt({},{},{})", m_N, m_r, m_p);
}

size_t Scrypt::total_memory_usage() const {
   const size_t N = memory_param();
   const size_t p = parallelism();
   const size_t r = iterations();

   return scrypt_memory_usage(N, r, p);
}

namespace {

void scryptBlockMix(size_t r, uint8_t* B, uint8_t* Y) {
   uint32_t B32[16];
   secure_vector<uint8_t> X(64);
   copy_mem(X.data(), &B[(2 * r - 1) * 64], 64);

   for(size_t i = 0; i != 2 * r; i++) {
      xor_buf(X.data(), &B[64 * i], 64);
      load_le<uint32_t>(B32, X.data(), 16);
      Salsa20::salsa_core(X.data(), B32, 8);
      copy_mem(&Y[64 * i], X.data(), 64);
   }

   for(size_t i = 0; i < r; ++i) {
      copy_mem(&B[i * 64], &Y[(i * 2) * 64], 64);
   }

   for(size_t i = 0; i < r; ++i) {
      copy_mem(&B[(i + r) * 64], &Y[(i * 2 + 1) * 64], 64);
   }
}

void scryptROMmix(size_t r, size_t N, uint8_t* B, secure_vector<uint8_t>& V) {
   const size_t S = 128 * r;

   for(size_t i = 0; i != N; ++i) {
      copy_mem(&V[S * i], B, S);
      scryptBlockMix(r, B, &V[N * S]);
   }

   for(size_t i = 0; i != N; ++i) {
      // compiler doesn't know here that N is power of 2
      const size_t j = load_le<uint32_t>(&B[(2 * r - 1) * 64], 0) & (N - 1);
      xor_buf(B, &V[j * S], S);
      scryptBlockMix(r, B, &V[N * S]);
   }
}

}  // namespace

void Scrypt::derive_key(uint8_t output[],
                        size_t output_len,
                        const char* password,
                        size_t password_len,
                        const uint8_t salt[],
                        size_t salt_len) const {
   const size_t N = memory_param();
   const size_t p = parallelism();
   const size_t r = iterations();

   const size_t S = 128 * r;
   secure_vector<uint8_t> B(p * S);
   // temp space
   secure_vector<uint8_t> V((N + 1) * S);

   auto hmac_sha256 = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");

   try {
      hmac_sha256->set_key(as_span_of_bytes(password, password_len));
   } catch(Invalid_Key_Length&) {
      throw Invalid_Argument("Scrypt cannot accept passphrases of the provided length");
   }

   pbkdf2(*hmac_sha256, B.data(), B.size(), salt, salt_len, 1);

   // these can be parallel
   for(size_t i = 0; i != p; ++i) {
      scryptROMmix(r, N, &B[128 * r * i], V);
   }

   pbkdf2(*hmac_sha256, output, output_len, B.data(), B.size(), 1);
}

}  // namespace Botan

1	/**
2	* (C) 2018 Jack Lloyd
3	* (C) 2018 Ribose Inc
4	*
5	* Botan is released under the Simplified BSD License (see license.txt)
6	*/
7
8	#include <botan/scrypt.h>
9
10	#include <botan/exceptn.h>
11	#include <botan/pbkdf2.h>
12	#include <botan/internal/bit_ops.h>
13	#include <botan/internal/fmt.h>
14	#include <botan/internal/loadstor.h>
15	#include <botan/internal/mem_utils.h>
16	#include <botan/internal/salsa20.h>
17	#include <botan/internal/time_utils.h>
18
19	namespace Botan {
20
21	namespace {
22
23	size_t scrypt_memory_usage(size_t N, size_t r, size_t p) {	25✔
24	return 128 * r * (N + p);	25✔
25	}
26
27	} // namespace
28
29	std::string Scrypt_Family::name() const {	1✔
30	return "Scrypt";	1✔
31	}
32
33	std::unique_ptr<PasswordHash> Scrypt_Family::default_params() const {	2✔
34	return std::make_unique<Scrypt>(32768, 8, 1);	2✔
35	}
36
37	std::unique_ptr<PasswordHash> Scrypt_Family::tune_params(size_t /output_length/,	242✔
38	uint64_t desired_msec,
39	std::optional<size_t> max_memory,
40	uint64_t tuning_msec) const {
41	/*
42	* Some rough relations between scrypt parameters and runtime.
43	* Denote here by stime(N,r,p) the msec it takes to run scrypt.
44	*
45	* Empirically for smaller sizes:
46	* stime(N,8*r,p) / stime(N,r,p) is ~ 6-7
47	* stime(N,r,8p) / stime(N,r,8p) is ~ 7
48	* stime(2*N,r,p) / stime(N,r,p) is ~ 2
49	*
50	* Compute stime(8192,1,1) as baseline and extrapolate
51	*/
52
53	// If max_memory is nullopt or zero this becomes zero and is ignored
54	const size_t max_memory_bytes = max_memory.value_or(0) * 1024 * 1024;	242✔
55
56	// Starting parameters
57	size_t N = 8 * 1024;	242✔
58	size_t r = 1;	242✔
59	size_t p = 1;	242✔
60
61	auto pwdhash = this->from_params(N, r, p);	242✔
62
63	const uint64_t measured_time = measure_cost(tuning_msec, [&]() {	242✔
64	uint8_t output[32] = {0};	242✔
65	pwdhash->derive_key(output, sizeof(output), "test", 4, nullptr, 0);	242✔
66	});
67
68	const uint64_t target_nsec = desired_msec * static_cast<uint64_t>(1000000);	242✔
69
70	uint64_t est_nsec = measured_time;	242✔
71
72	// In below code we invoke scrypt_memory_usage with p == 0 as p contributes
73	// (very slightly) to memory consumption, but N is the driving factor.
74	// Including p leads to using an N half as large as what the user would expect.
75
76	// First increase r by 8x if possible
77	if(max_memory_bytes == 0 \|\| scrypt_memory_usage(N, r * 8, 0) <= max_memory_bytes) {	242✔
78	if(target_nsec / est_nsec >= 5) {	242✔
79	r *= 8;	8✔
80	est_nsec *= 5;	8✔
81	}
82	}
83
84	// Now double N as many times as we can
85	while(max_memory_bytes == 0 \|\| scrypt_memory_usage(N * 2, r, 0) <= max_memory_bytes) {	251✔
86	if(target_nsec / est_nsec >= 2) {	251✔
87	N *= 2;	9✔
88	est_nsec *= 2;	9✔
89	} else {
90	break;
91	}
92	}
93
94	// If we have extra runtime budget, increment p
95	if(target_nsec / est_nsec >= 2) {	242✔
96	p *= std::min<size_t>(1024, static_cast<size_t>(target_nsec / est_nsec));	×
97	}
98
99	return std::make_unique<Scrypt>(N, r, p);	242✔
100	}	242✔
101
102	std::unique_ptr<PasswordHash> Scrypt_Family::from_params(size_t N, size_t r, size_t p) const {	511✔
103	return std::make_unique<Scrypt>(N, r, p);	511✔
104	}
105
106	std::unique_ptr<PasswordHash> Scrypt_Family::from_iterations(size_t iter) const {	×
107	const size_t r = 8;	×
108	const size_t p = 1;	×
109
110	size_t N = 8192;	×
111
112	if(iter > 50000) {	×
113	N = 16384;	×
114	}
115	if(iter > 100000) {	×
116	N = 32768;	×
117	}
118	if(iter > 150000) {	×
119	N = 65536;	×
120	}
121
122	return std::make_unique<Scrypt>(N, r, p);	×
123	}
124
125	Scrypt::Scrypt(size_t N, size_t r, size_t p) : m_N(N), m_r(r), m_p(p) {	755✔
126	if(!is_power_of_2(N)) {	755✔
127	throw Invalid_Argument("Scrypt N parameter must be a power of 2");	×
128	}
129
130	if(p == 0 \|\| p > 1024) {	755✔
131	throw Invalid_Argument("Invalid or unsupported scrypt p");	×
132	}
133	if(r == 0 \|\| r > 256) {	755✔
134	throw Invalid_Argument("Invalid or unsupported scrypt r");	×
135	}
136	if(N < 1 \|\| N > 4194304) {	755✔
137	throw Invalid_Argument("Invalid or unsupported scrypt N");	×
138	}
139	}	755✔
140
141	std::string Scrypt::to_string() const {	4✔
142	return fmt("Scrypt({},{},{})", m_N, m_r, m_p);	4✔
143	}
144
145	size_t Scrypt::total_memory_usage() const {	20✔
146	const size_t N = memory_param();	20✔
147	const size_t p = parallelism();	20✔
148	const size_t r = iterations();	20✔
149
150	return scrypt_memory_usage(N, r, p);	20✔
151	}
152
153	namespace {
154
155	void scryptBlockMix(size_t r, uint8_t* B, uint8_t* Y) {	17,466,840✔
156	uint32_t B32[16];	17,466,840✔
157	secure_vector<uint8_t> X(64);	17,466,840✔
158	copy_mem(X.data(), &B[(2 * r - 1) * 64], 64);	17,466,840✔
159
160	for(size_t i = 0; i != 2 * r; i++) {	130,913,960✔
161	xor_buf(X.data(), &B[64 * i], 64);	113,447,120✔
162	load_le<uint32_t>(B32, X.data(), 16);	113,447,120✔
163	Salsa20::salsa_core(X.data(), B32, 8);	113,447,120✔
164	copy_mem(&Y[64 * i], X.data(), 64);	113,447,120✔
165	}
166
167	for(size_t i = 0; i < r; ++i) {	74,190,400✔
168	copy_mem(&B[i * 64], &Y[(i * 2) * 64], 64);	56,723,560✔
169	}
170
171	for(size_t i = 0; i < r; ++i) {	74,190,400✔
172	copy_mem(&B[(i + r) * 64], &Y[(i * 2 + 1) * 64], 64);	56,723,560✔
173	}
174	}	17,466,840✔
175
176	void scryptROMmix(size_t r, size_t N, uint8_t* B, secure_vector<uint8_t>& V) {	1,118✔
177	const size_t S = 128 * r;	1,118✔
178
179	for(size_t i = 0; i != N; ++i) {	8,734,538✔
180	copy_mem(&V[S * i], B, S);	8,733,420✔
181	scryptBlockMix(r, B, &V[N * S]);	8,733,420✔
182	}
183
184	for(size_t i = 0; i != N; ++i) {	8,734,538✔
185	// compiler doesn't know here that N is power of 2
186	const size_t j = load_le<uint32_t>(&B[(2 * r - 1) * 64], 0) & (N - 1);	8,733,420✔
187	xor_buf(B, &V[j * S], S);	8,733,420✔
188	scryptBlockMix(r, B, &V[N * S]);	8,733,420✔
189	}
190	}	1,118✔
191
192	} // namespace
193
194	void Scrypt::derive_key(uint8_t output[],	755✔
195	size_t output_len,
196	const char* password,
197	size_t password_len,
198	const uint8_t salt[],
199	size_t salt_len) const {
200	const size_t N = memory_param();	755✔
201	const size_t p = parallelism();	755✔
202	const size_t r = iterations();	755✔
203
204	const size_t S = 128 * r;	755✔
205	secure_vector<uint8_t> B(p * S);	755✔
206	// temp space
207	secure_vector<uint8_t> V((N + 1) * S);	755✔
208
209	auto hmac_sha256 = MessageAuthenticationCode::create_or_throw("HMAC(SHA-256)");	755✔
210
211	try {	755✔
212	hmac_sha256->set_key(as_span_of_bytes(password, password_len));	755✔
213	} catch(Invalid_Key_Length&) {	×
214	throw Invalid_Argument("Scrypt cannot accept passphrases of the provided length");	×
215	}	×
216
217	pbkdf2(*hmac_sha256, B.data(), B.size(), salt, salt_len, 1);	755✔
218
219	// these can be parallel
220	for(size_t i = 0; i != p; ++i) {	1,873✔
221	scryptROMmix(r, N, &B[128 * r * i], V);	1,118✔
222	}
223
224	pbkdf2(*hmac_sha256, output, output_len, B.data(), B.size(), 1);	755✔
225	}	2,265✔
226
227	} // namespace Botan

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