Botan 2.19.1
Crypto and TLS for C&
Public Member Functions | Static Public Member Functions | List of all members
Botan::Scrypt_Family Class Referencefinal

#include <scrypt.h>

Inheritance diagram for Botan::Scrypt_Family:
Botan::PasswordHashFamily

Public Member Functions

std::unique_ptr< PasswordHashdefault_params () const override
 
std::unique_ptr< PasswordHashfrom_iterations (size_t iter) const override
 
std::unique_ptr< PasswordHashfrom_params (size_t N, size_t r, size_t p) const override
 
std::string name () const override
 
std::unique_ptr< PasswordHashtune (size_t output_length, std::chrono::milliseconds msec, size_t max_memory) const override
 

Static Public Member Functions

static std::unique_ptr< PasswordHashFamilycreate (const std::string &algo_spec, const std::string &provider="")
 
static std::unique_ptr< PasswordHashFamilycreate_or_throw (const std::string &algo_spec, const std::string &provider="")
 
static std::vector< std::string > providers (const std::string &algo_spec)
 

Detailed Description

Definition at line 53 of file scrypt.h.

Member Function Documentation

◆ create()

std::unique_ptr< PasswordHashFamily > Botan::PasswordHashFamily::create ( const std::string &  algo_spec,
const std::string &  provider = "" 
)
staticinherited

Create an instance based on a name If provider is empty then best available is chosen.

Parameters
algo_specalgorithm name
providerprovider implementation to choose
Returns
a null pointer if the algo/provider combination cannot be found

Definition at line 33 of file pwdhash.cpp.

35 {
36 const SCAN_Name req(algo_spec);
37
38#if defined(BOTAN_HAS_PBKDF2)
39 if(req.algo_name() == "PBKDF2")
40 {
41 // TODO OpenSSL
42
43 if(provider.empty() || provider == "base")
44 {
45 if(auto mac = MessageAuthenticationCode::create(req.arg(0)))
46 return std::unique_ptr<PasswordHashFamily>(new PBKDF2_Family(mac.release()));
47
48 if(auto mac = MessageAuthenticationCode::create("HMAC(" + req.arg(0) + ")"))
49 return std::unique_ptr<PasswordHashFamily>(new PBKDF2_Family(mac.release()));
50 }
51
52 return nullptr;
53 }
54#endif
55
56#if defined(BOTAN_HAS_SCRYPT)
57 if(req.algo_name() == "Scrypt")
58 {
59 return std::unique_ptr<PasswordHashFamily>(new Scrypt_Family);
60 }
61#endif
62
63#if defined(BOTAN_HAS_ARGON2)
64 if(req.algo_name() == "Argon2d")
65 {
66 return std::unique_ptr<PasswordHashFamily>(new Argon2_Family(0));
67 }
68 else if(req.algo_name() == "Argon2i")
69 {
70 return std::unique_ptr<PasswordHashFamily>(new Argon2_Family(1));
71 }
72 else if(req.algo_name() == "Argon2id")
73 {
74 return std::unique_ptr<PasswordHashFamily>(new Argon2_Family(2));
75 }
76#endif
77
78#if defined(BOTAN_HAS_PBKDF_BCRYPT)
79 if(req.algo_name() == "Bcrypt-PBKDF")
80 {
81 return std::unique_ptr<PasswordHashFamily>(new Bcrypt_PBKDF_Family);
82 }
83#endif
84
85#if defined(BOTAN_HAS_PGP_S2K)
86 if(req.algo_name() == "OpenPGP-S2K" && req.arg_count() == 1)
87 {
88 if(auto hash = HashFunction::create(req.arg(0)))
89 {
90 return std::unique_ptr<PasswordHashFamily>(new RFC4880_S2K_Family(hash.release()));
91 }
92 }
93#endif
94
95 BOTAN_UNUSED(req);
96 BOTAN_UNUSED(provider);
97
98 return nullptr;
99 }
#define BOTAN_UNUSED(...)
Definition: assert.h:142
static std::unique_ptr< HashFunction > create(const std::string &algo_spec, const std::string &provider="")
Definition: hash.cpp:106
static std::unique_ptr< MessageAuthenticationCode > create(const std::string &algo_spec, const std::string &provider="")
Definition: mac.cpp:46
MechanismType hash

References Botan::SCAN_Name::algo_name(), Botan::SCAN_Name::arg(), Botan::SCAN_Name::arg_count(), BOTAN_UNUSED, Botan::HashFunction::create(), Botan::MessageAuthenticationCode::create(), and hash.

Referenced by botan_pwdhash(), botan_pwdhash_timed(), and Botan::PasswordHashFamily::create_or_throw().

◆ create_or_throw()

std::unique_ptr< PasswordHashFamily > Botan::PasswordHashFamily::create_or_throw ( const std::string &  algo_spec,
const std::string &  provider = "" 
)
staticinherited

Create an instance based on a name, or throw if the algo/provider combination cannot be found. If provider is empty then best available is chosen.

Definition at line 103 of file pwdhash.cpp.

105 {
106 if(auto pbkdf = PasswordHashFamily::create(algo, provider))
107 {
108 return pbkdf;
109 }
110 throw Lookup_Error("PasswordHashFamily", algo, provider);
111 }
static std::unique_ptr< PasswordHashFamily > create(const std::string &algo_spec, const std::string &provider="")
Definition: pwdhash.cpp:33

References Botan::PasswordHashFamily::create().

◆ default_params()

std::unique_ptr< PasswordHash > Botan::Scrypt_Family::default_params ( ) const
overridevirtual

Return some default parameter set for this PBKDF that should be good enough for most users. The value returned may change over time as processing power and attacks improve.

Implements Botan::PasswordHashFamily.

Definition at line 24 of file scrypt.cpp.

25 {
26 return std::unique_ptr<PasswordHash>(new Scrypt(32768, 8, 1));
27 }

Referenced by tune().

◆ from_iterations()

std::unique_ptr< PasswordHash > Botan::Scrypt_Family::from_iterations ( size_t  iterations) const
overridevirtual

Return a parameter chosen based on a rough approximation with the specified iteration count. The exact value this returns for a particular algorithm may change from over time. Think of it as an alternative to tune, where time is expressed in terms of PBKDF2 iterations rather than milliseconds.

Implements Botan::PasswordHashFamily.

Definition at line 110 of file scrypt.cpp.

111 {
112 const size_t r = 8;
113 const size_t p = 1;
114
115 size_t N = 8192;
116
117 if(iter > 50000)
118 N = 16384;
119 if(iter > 100000)
120 N = 32768;
121 if(iter > 150000)
122 N = 65536;
123
124 return std::unique_ptr<PasswordHash>(new Scrypt(N, r, p));
125 }

◆ from_params()

std::unique_ptr< PasswordHash > Botan::Scrypt_Family::from_params ( size_t  i1,
size_t  i2,
size_t  i3 
) const
overridevirtual

Create a password hash using some scheme specific format. Eg PBKDF2 and PGP-S2K set iterations in i1 Scrypt uses N,r,p in i{1-3} Bcrypt-PBKDF just has iterations Argon2{i,d,id} would use iterations, memory, parallelism for i{1-3}, and Argon2 type is part of the family.

Values not needed should be set to 0

Implements Botan::PasswordHashFamily.

Definition at line 105 of file scrypt.cpp.

106 {
107 return std::unique_ptr<PasswordHash>(new Scrypt(N, r, p));
108 }

◆ name()

std::string Botan::Scrypt_Family::name ( ) const
overridevirtual
Returns
name of this PasswordHash

Implements Botan::PasswordHashFamily.

Definition at line 19 of file scrypt.cpp.

20 {
21 return "Scrypt";
22 }

◆ providers()

std::vector< std::string > Botan::PasswordHashFamily::providers ( const std::string &  algo_spec)
staticinherited
Returns
list of available providers for this algorithm, empty if not available

Definition at line 113 of file pwdhash.cpp.

114 {
115 return probe_providers_of<PasswordHashFamily>(algo_spec, { "base", "openssl" });
116 }

◆ tune()

std::unique_ptr< PasswordHash > Botan::Scrypt_Family::tune ( size_t  output_length,
std::chrono::milliseconds  msec,
size_t  max_memory_usage_mb 
) const
overridevirtual

Return a new parameter set tuned for this machine

Parameters
output_lengthhow long the output length will be
msecthe desired execution time in milliseconds
max_memory_usage_mbsome password hash functions can use a tunable amount of memory, in this case max_memory_usage limits the amount of RAM the returned parameters will require, in mebibytes (2**20 bytes). It may require some small amount above the request. Set to zero to place no limit at all.

Implements Botan::PasswordHashFamily.

Definition at line 29 of file scrypt.cpp.

32 {
33 BOTAN_UNUSED(output_length);
34
35 /*
36 * Some rough relations between scrypt parameters and runtime.
37 * Denote here by stime(N,r,p) the msec it takes to run scrypt.
38 *
39 * Emperically for smaller sizes:
40 * stime(N,8*r,p) / stime(N,r,p) is ~ 6-7
41 * stime(N,r,8*p) / stime(N,r,8*p) is ~ 7
42 * stime(2*N,r,p) / stime(N,r,p) is ~ 2
43 *
44 * Compute stime(8192,1,1) as baseline and extrapolate
45 */
46
47 const size_t max_memory_usage = max_memory_usage_mb * 1024 * 1024;
48 // Starting parameters
49 size_t N = 8192;
50 size_t r = 1;
51 size_t p = 1;
52
53 Timer timer("Scrypt");
54 const auto tune_time = BOTAN_PBKDF_TUNING_TIME;
55
56 timer.run_until_elapsed(tune_time, [&]() {
57 uint8_t output[32] = { 0 };
58 scrypt(output, sizeof(output), "test", 4, nullptr, 0, N, r, p);
59 });
60
61 // No timer events seems strange, perhaps something is wrong - give
62 // up on this and just return default params
63 if(timer.events() == 0)
64 return default_params();
65
66 // nsec per eval of scrypt with initial params
67 const uint64_t measured_time = timer.value() / timer.events();
68
69 const uint64_t target_nsec = msec.count() * static_cast<uint64_t>(1000000);
70
71 uint64_t est_nsec = measured_time;
72
73 // First move increase r by 8x if possible
74
75 if(max_memory_usage == 0 || scrypt_memory_usage(N, r, p)*8 < max_memory_usage)
76 {
77 if(target_nsec / est_nsec >= 5)
78 {
79 r *= 8;
80 est_nsec *= 5;
81 }
82 }
83
84 // Now double N as many times as we can
85
86 while(max_memory_usage == 0 || scrypt_memory_usage(N, r, p)*2 < max_memory_usage)
87 {
88 if(target_nsec / est_nsec >= 2)
89 {
90 N *= 2;
91 est_nsec *= 2;
92 }
93 else
94 break;
95 }
96
97 // If we have extra runtime budget, increment p
98
99 if(target_nsec / est_nsec > 2)
100 p *= std::min<size_t>(1024, static_cast<size_t>(target_nsec / est_nsec));
101
102 return std::unique_ptr<PasswordHash>(new Scrypt(N, r, p));
103 }
std::unique_ptr< PasswordHash > default_params() const override
Definition: scrypt.cpp:24
size_t scrypt_memory_usage(size_t N, size_t r, size_t p)
Definition: scrypt.h:120
void scrypt(uint8_t output[], size_t output_len, const char *password, size_t password_len, const uint8_t salt[], size_t salt_len, size_t N, size_t r, size_t p)
Definition: scrypt.cpp:211

References BOTAN_UNUSED, default_params(), Botan::Timer::events(), Botan::Timer::run_until_elapsed(), Botan::scrypt(), Botan::scrypt_memory_usage(), and Botan::Timer::value().


The documentation for this class was generated from the following files: