Botan 2.19.2
Crypto and TLS for C&
bcrypt_pbkdf.cpp
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1/*
2* (C) 2018,2019 Jack Lloyd
3*
4* Botan is released under the Simplified BSD License (see license.txt)
5*/
6
7#include <botan/bcrypt_pbkdf.h>
8#include <botan/loadstor.h>
9#include <botan/blowfish.h>
10#include <botan/hash.h>
11#include <botan/internal/timer.h>
12
13namespace Botan {
14
15void Bcrypt_PBKDF::derive_key(uint8_t output[], size_t output_len,
16 const char* password, size_t password_len,
17 const uint8_t salt[], size_t salt_len) const
18 {
19 bcrypt_pbkdf(output, output_len,
20 password, password_len,
21 salt, salt_len,
22 m_iterations);
23 }
24
25std::string Bcrypt_PBKDF::to_string() const
26 {
27 return "Bcrypt-PBKDF(" + std::to_string(m_iterations) + ")";
28 }
29
30std::string Bcrypt_PBKDF_Family::name() const
31 {
32 return "Bcrypt-PBKDF";
33 }
34
35std::unique_ptr<PasswordHash> Bcrypt_PBKDF_Family::tune(size_t output_length,
36 std::chrono::milliseconds msec,
37 size_t /*max_memory*/) const
38 {
39 Timer timer("Bcrypt_PBKDF");
40 const auto tune_time = BOTAN_PBKDF_TUNING_TIME;
41
42 const size_t blocks = (output_length + 32 - 1) / 32;
43
44 if(blocks == 0)
45 return default_params();
46
47 const size_t starting_iter = 2;
48
49 timer.run_until_elapsed(tune_time, [&]() {
50 uint8_t output[32] = { 0 };
51 bcrypt_pbkdf(output, sizeof(output), "test", 4, nullptr, 0, starting_iter);
52 });
53
54 if(timer.events() < blocks || timer.value() == 0)
55 return default_params();
56
57 const uint64_t measured_time = timer.value() / (timer.events() / blocks);
58
59 const uint64_t target_nsec = msec.count() * static_cast<uint64_t>(1000000);
60
61 const uint64_t desired_increase = target_nsec / measured_time;
62
63 if(desired_increase == 0)
64 return this->from_iterations(starting_iter);
65
66 return this->from_iterations(static_cast<size_t>(desired_increase * starting_iter));
67 }
68
69std::unique_ptr<PasswordHash> Bcrypt_PBKDF_Family::default_params() const
70 {
71 return this->from_iterations(32); // About 100 ms on fast machine
72 }
73
74std::unique_ptr<PasswordHash> Bcrypt_PBKDF_Family::from_iterations(size_t iter) const
75 {
76 return std::unique_ptr<PasswordHash>(new Bcrypt_PBKDF(iter));
77 }
78
79std::unique_ptr<PasswordHash> Bcrypt_PBKDF_Family::from_params(size_t iter, size_t /*t*/, size_t /*p*/) const
80 {
81 return this->from_iterations(iter);
82 }
83
84namespace {
85
86void bcrypt_round(Blowfish& blowfish,
87 const secure_vector<uint8_t>& pass_hash,
88 const secure_vector<uint8_t>& salt_hash,
91 {
92 const size_t BCRYPT_PBKDF_OUTPUT = 32;
93
94 // "OxychromaticBlowfishSwatDynamite"
95 static const uint8_t BCRYPT_PBKDF_MAGIC[BCRYPT_PBKDF_OUTPUT] = {
96 0x4F, 0x78, 0x79, 0x63, 0x68, 0x72, 0x6F, 0x6D,
97 0x61, 0x74, 0x69, 0x63, 0x42, 0x6C, 0x6F, 0x77,
98 0x66, 0x69, 0x73, 0x68, 0x53, 0x77, 0x61, 0x74,
99 0x44, 0x79, 0x6E, 0x61, 0x6D, 0x69, 0x74, 0x65
100 };
101
102 const size_t BCRYPT_PBKDF_WORKFACTOR = 6;
103 const size_t BCRYPT_PBKDF_ROUNDS = 64;
104
105 blowfish.salted_set_key(pass_hash.data(), pass_hash.size(),
106 salt_hash.data(), salt_hash.size(),
107 BCRYPT_PBKDF_WORKFACTOR, true);
108
109 copy_mem(tmp.data(), BCRYPT_PBKDF_MAGIC, BCRYPT_PBKDF_OUTPUT);
110 for(size_t i = 0; i != BCRYPT_PBKDF_ROUNDS; ++i)
111 blowfish.encrypt(tmp);
112
113 /*
114 Bcrypt PBKDF loads the Blowfish output as big endian for no reason
115 in particular. We can't just swap everything once at the end
116 because the (big-endian) values are fed into SHA-512 to generate
117 the salt for the next round
118 */
119 for(size_t i = 0; i != 32/4; ++i)
120 {
121 const uint32_t w = load_le<uint32_t>(tmp.data(), i);
122 store_be(w, &tmp[sizeof(uint32_t)*i]);
123 }
124
125 xor_buf(out.data(), tmp.data(), BCRYPT_PBKDF_OUTPUT);
126 }
127
128}
129
130void bcrypt_pbkdf(uint8_t output[], size_t output_len,
131 const char* pass, size_t pass_len,
132 const uint8_t salt[], size_t salt_len,
133 size_t rounds)
134 {
135 BOTAN_ARG_CHECK(rounds >= 1, "Invalid rounds for Bcrypt PBKDF");
136
137 // No output desired, so we are all done already...
138 if(output_len == 0)
139 return;
140
141 BOTAN_ARG_CHECK(output_len <= 10*1024*1024, "Too much output for Bcrypt PBKDF");
142
143 const size_t BCRYPT_BLOCK_SIZE = 32;
144 const size_t blocks = (output_len + BCRYPT_BLOCK_SIZE - 1) / BCRYPT_BLOCK_SIZE;
145
146 std::unique_ptr<HashFunction> sha512 = HashFunction::create_or_throw("SHA-512");
147 const secure_vector<uint8_t> pass_hash = sha512->process(reinterpret_cast<const uint8_t*>(pass), pass_len);
148
149 secure_vector<uint8_t> salt_hash(sha512->output_length());
150
151 Blowfish blowfish;
152 secure_vector<uint8_t> out(BCRYPT_BLOCK_SIZE);
153 secure_vector<uint8_t> tmp(BCRYPT_BLOCK_SIZE);
154
155 for(size_t block = 0; block != blocks; ++block)
156 {
157 clear_mem(out.data(), out.size());
158
159 sha512->update(salt, salt_len);
160 sha512->update_be(static_cast<uint32_t>(block + 1));
161 sha512->final(salt_hash.data());
162
163 bcrypt_round(blowfish, pass_hash, salt_hash, out, tmp);
164
165 for(size_t r = 1; r != rounds; ++r)
166 {
167 // Next salt is H(prev_output)
168 sha512->update(tmp);
169 sha512->final(salt_hash.data());
170
171 bcrypt_round(blowfish, pass_hash, salt_hash, out, tmp);
172 }
173
174 for(size_t i = 0; i != BCRYPT_BLOCK_SIZE; ++i)
175 {
176 const size_t dest = i * blocks + block;
177 if(dest < output_len)
178 output[dest] = out[i];
179 }
180 }
181 }
182
183}
#define BOTAN_ARG_CHECK(expr, msg)
Definition: assert.h:37
std::unique_ptr< PasswordHash > from_params(size_t i, size_t, size_t) const override
std::unique_ptr< PasswordHash > default_params() const override
std::string name() const override
std::unique_ptr< PasswordHash > from_iterations(size_t iter) const override
std::unique_ptr< PasswordHash > tune(size_t output_length, std::chrono::milliseconds msec, size_t max_memory) const override
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
std::string to_string() const override
void encrypt(const uint8_t in[], uint8_t out[]) const
Definition: block_cipher.h:82
void salted_set_key(const uint8_t key[], size_t key_length, const uint8_t salt[], size_t salt_length, const size_t workfactor, bool salt_first=false)
Definition: blowfish.cpp:375
static std::unique_ptr< HashFunction > create_or_throw(const std::string &algo_spec, const std::string &provider="")
Definition: hash.cpp:329
uint64_t value() const
Definition: timer.h:90
uint64_t events() const
Definition: timer.h:119
void run_until_elapsed(std::chrono::milliseconds msec, F f)
Definition: timer.h:82
std::string to_string(const BER_Object &obj)
Definition: asn1_obj.cpp:213
Definition: alg_id.cpp:13
void bcrypt_pbkdf(uint8_t output[], size_t output_len, const char *pass, size_t pass_len, const uint8_t salt[], size_t salt_len, size_t rounds)
void store_be(uint16_t in, uint8_t out[2])
Definition: loadstor.h:438
uint32_t load_le< uint32_t >(const uint8_t in[], size_t off)
Definition: loadstor.h:198
void copy_mem(T *out, const T *in, size_t n)
Definition: mem_ops.h:133
void xor_buf(uint8_t out[], const uint8_t in[], size_t length)
Definition: mem_ops.h:262
std::vector< T, secure_allocator< T > > secure_vector
Definition: secmem.h:65
void clear_mem(T *ptr, size_t n)
Definition: mem_ops.h:115
size_t salt_len
Definition: x509_obj.cpp:25