Botan 3.0.0
Crypto and TLS for C&
Functions
ffi_rng.cpp File Reference
#include <botan/ffi.h>
#include <botan/internal/ffi_util.h>
#include <botan/internal/ffi_rng.h>
#include <botan/system_rng.h>
#include <botan/auto_rng.h>
#include <functional>
#include <memory>

Go to the source code of this file.

Functions

int botan_rng_add_entropy (botan_rng_t rng, const uint8_t *input, size_t len)
 
int botan_rng_destroy (botan_rng_t rng)
 
int botan_rng_get (botan_rng_t rng, uint8_t *out, size_t out_len)
 
int botan_rng_init (botan_rng_t *rng_out, const char *rng_type)
 
int botan_rng_init_custom (botan_rng_t *rng_out, const char *rng_name, void *context, int(*get_cb)(void *context, uint8_t *out, size_t out_len), int(*add_entropy_cb)(void *context, const uint8_t input[], size_t length), void(*destroy_cb)(void *context))
 
int botan_rng_reseed (botan_rng_t rng, size_t bits)
 
int botan_rng_reseed_from_rng (botan_rng_t rng, botan_rng_t source_rng, size_t bits)
 
int botan_system_rng_get (uint8_t *out, size_t out_len)
 

Function Documentation

◆ botan_rng_add_entropy()

int botan_rng_add_entropy ( botan_rng_t  rng,
const uint8_t *  entropy,
size_t  entropy_len 
)

Add some seed material to a random number generator

Parameters
rngrng object
entropythe data to add
entropy_lenlength of entropy buffer
Returns
0 on success, a negative value on failure

Definition at line 188 of file ffi_rng.cpp.

189 {
190 return BOTAN_FFI_VISIT(rng, [=](auto& r) { r.add_entropy(input, len); });
191 }
#define BOTAN_FFI_VISIT(obj, lambda)
Definition: ffi_util.h:126

References BOTAN_FFI_VISIT.

◆ botan_rng_destroy()

int botan_rng_destroy ( botan_rng_t  rng)

Frees all resources of the random number generator object

Parameters
rngrng object
Returns
0 if success, error if invalid object handle

Definition at line 164 of file ffi_rng.cpp.

165 {
166 return BOTAN_FFI_CHECKED_DELETE(rng);
167 }
#define BOTAN_FFI_CHECKED_DELETE(o)
Definition: ffi_util.h:145

References BOTAN_FFI_CHECKED_DELETE.

◆ botan_rng_get()

int botan_rng_get ( botan_rng_t  rng,
uint8_t *  out,
size_t  out_len 
)

Get random bytes from a random number generator

Parameters
rngrng object
outoutput buffer of size out_len
out_lennumber of requested bytes
Returns
0 on success, negative on failure

Definition at line 169 of file ffi_rng.cpp.

170 {
171 return BOTAN_FFI_VISIT(rng, [=](auto& r) { r.randomize(out, out_len); });
172 }

References BOTAN_FFI_VISIT.

◆ botan_rng_init()

int botan_rng_init ( botan_rng_t rng,
const char *  rng_type 
)

Initialize a random number generator object

Parameters
rngrng object
rng_typetype of the rng, possible values: "system": system RNG "user": userspace RNG "user-threadsafe": userspace RNG, with internal locking "rdrand": directly read RDRAND Set rng_type to null to let the library choose some default.

Definition at line 25 of file ffi_rng.cpp.

26 {
27 return ffi_guard_thunk(__func__, [=]() -> int {
28 if(rng_out == nullptr)
30
31 const std::string rng_type_s(rng_type ? rng_type : "system");
32
33 std::unique_ptr<Botan::RandomNumberGenerator> rng;
34
35 if(rng_type_s == "system")
36 {
37 rng = std::make_unique<Botan::System_RNG>();
38 }
39 else if(rng_type_s == "user" || rng_type_s == "user-threadsafe")
40 {
41 rng = std::make_unique<Botan::AutoSeeded_RNG>();
42 }
43 else if(rng_type_s == "null")
44 {
45 rng = std::make_unique<Botan::Null_RNG>();
46 }
47#if defined(BOTAN_HAS_PROCESSOR_RNG)
48 else if((rng_type_s == "rdrand" || rng_type_s == "hwrng") && Botan::Processor_RNG::available())
49 {
50 rng = std::make_unique<Botan::Processor_RNG>();
51 }
52#endif
53
54 if(!rng)
55 {
57 }
58
59 *rng_out = new botan_rng_struct(std::move(rng));
60 return BOTAN_FFI_SUCCESS;
61 });
62 }
static bool available()
@ BOTAN_FFI_ERROR_NOT_IMPLEMENTED
Definition: ffi.h:91
@ BOTAN_FFI_ERROR_NULL_POINTER
Definition: ffi.h:85
@ BOTAN_FFI_SUCCESS
Definition: ffi.h:70
int ffi_guard_thunk(const char *func_name, const std::function< int()> &thunk)
Definition: ffi.cpp:120

References Botan::Processor_RNG::available(), BOTAN_FFI_ERROR_NOT_IMPLEMENTED, BOTAN_FFI_ERROR_NULL_POINTER, BOTAN_FFI_SUCCESS, and Botan_FFI::ffi_guard_thunk().

◆ botan_rng_init_custom()

int botan_rng_init_custom ( botan_rng_t rng_out,
const char *  rng_name,
void *  context,
int(*)(void *context, uint8_t *out, size_t out_len)  get_cb,
int(*)(void *context, const uint8_t input[], size_t length)  add_entropy_cb,
void(*)(void *context)  destroy_cb 
)

Initialize a custom random number generator from a set of callback functions

Parameters
rng_outrng object to create
rng_namename of the rng
contextAn application-specific context passed to the callback functions
get_cbCallback for getting random bytes from the rng, return 0 for success
add_entropy_cbCallback for adding entropy to the rng, return 0 for success, may be NULL
destroy_cbCallback called when rng is destroyed, may be NULL

Definition at line 64 of file ffi_rng.cpp.

68 {
69 return ffi_guard_thunk(__func__,[=]() -> int {
70 if(rng_out == nullptr)
72
73 if(rng_name == nullptr)
75
76 if(get_cb == nullptr)
78
79 class Custom_RNG : public Botan::RandomNumberGenerator
80 {
81 public:
82 Custom_RNG(std::string_view name, void* context,
83 int(* get_cb)(void* context, uint8_t* out, size_t out_len),
84 int(* add_entropy_cb)(void* context, const uint8_t input[], size_t length),
85 void(* destroy_cb)(void* context)) :
86 m_name(name)
87 {
88 m_context = context;
89 m_get_cb = get_cb;
90 m_add_entropy_cb = add_entropy_cb;
91 m_destroy_cb = destroy_cb;
92 }
93
94 ~Custom_RNG() override
95 {
96 if(m_destroy_cb)
97 {
98 m_destroy_cb(m_context);
99 }
100 }
101
102 Custom_RNG(const Custom_RNG& other) = delete;
103 Custom_RNG(Custom_RNG&& other) = delete;
104 Custom_RNG& operator=(const Custom_RNG& other) = delete;
105 Custom_RNG& operator=(Custom_RNG&& other) = delete;
106
107 protected:
108 void fill_bytes_with_input(std::span<uint8_t> output, std::span<const uint8_t> input) override
109 {
110 if(accepts_input() && !input.empty())
111 {
112 int rc = m_add_entropy_cb(m_context, input.data(), input.size());
113 if(rc)
114 {
115 throw Botan::Invalid_State("Failed to add entropy via C callback, rc=" + std::to_string(rc));
116 }
117 }
118
119 if(!output.empty())
120 {
121 int rc = m_get_cb(m_context, output.data(), output.size());
122 if(rc)
123 {
124 throw Botan::Invalid_State("Failed to get random from C callback, rc=" + std::to_string(rc));
125 }
126 }
127 }
128
129 public:
130 bool accepts_input() const override
131 {
132 return m_add_entropy_cb != nullptr;
133 }
134
135 std::string name() const override
136 {
137 return m_name;
138 }
139
140 void clear() override
141 {
142 }
143
144 bool is_seeded() const override
145 {
146 return true;
147 }
148
149 private:
150 std::string m_name;
151 void* m_context;
152 std::function<int(void* context, uint8_t* out, size_t out_len)> m_get_cb;
153 std::function<int(void* context, const uint8_t input[], size_t length)> m_add_entropy_cb;
154 std::function<void(void* context)> m_destroy_cb;
155 };
156
157 auto rng = std::make_unique<Custom_RNG>(rng_name, context, get_cb, add_entropy_cb, destroy_cb);
158
159 *rng_out = new botan_rng_struct(std::move(rng));
160 return BOTAN_FFI_SUCCESS;
161 });
162 }
std::string name

References BOTAN_FFI_ERROR_NULL_POINTER, BOTAN_FFI_SUCCESS, Botan_FFI::ffi_guard_thunk(), and name.

◆ botan_rng_reseed()

int botan_rng_reseed ( botan_rng_t  rng,
size_t  bits 
)

Reseed a random number generator Uses the System_RNG as a seed generator.

Parameters
rngrng object
bitsnumber of bits to reseed with
Returns
0 on success, a negative value on failure

Definition at line 183 of file ffi_rng.cpp.

184 {
185 return BOTAN_FFI_VISIT(rng, [=](auto& r) { r.reseed_from_rng(Botan::system_rng(), bits); });
186 }
RandomNumberGenerator & system_rng()
Definition: system_rng.cpp:376

References BOTAN_FFI_VISIT, and Botan::system_rng().

◆ botan_rng_reseed_from_rng()

int botan_rng_reseed_from_rng ( botan_rng_t  rng,
botan_rng_t  source_rng,
size_t  bits 
)

Reseed a random number generator

Parameters
rngrng object
source_rngthe rng that will be read from
bitsnumber of bits to reseed with
Returns
0 on success, a negative value on failure

Definition at line 193 of file ffi_rng.cpp.

194 {
195 return BOTAN_FFI_VISIT(rng, [=](auto& r) { r.reseed_from_rng(safe_get(source_rng), bits); });
196 }
T & safe_get(botan_struct< T, M > *p)
Definition: ffi_util.h:69

References BOTAN_FFI_VISIT, and Botan_FFI::safe_get().

◆ botan_system_rng_get()

int botan_system_rng_get ( uint8_t *  out,
size_t  out_len 
)

Get random bytes from system random number generator

Parameters
outoutput buffer of size out_len
out_lennumber of requested bytes
Returns
0 on success, negative on failure

Definition at line 174 of file ffi_rng.cpp.

175 {
176 return ffi_guard_thunk(__func__, [=]() -> int
177 {
178 Botan::system_rng().randomize(out, out_len);
179 return BOTAN_FFI_SUCCESS;
180 });
181 }
void randomize(std::span< uint8_t > output)
Definition: rng.h:53

References BOTAN_FFI_SUCCESS, Botan_FFI::ffi_guard_thunk(), Botan::RandomNumberGenerator::randomize(), and Botan::system_rng().