5 provider-rand - The random number generation library E<lt>-E<gt> provider
10 =for openssl multiple includes
12 #include <openssl/core_dispatch.h>
13 #include <openssl/core_names.h>
16 * None of these are actual functions, but are displayed like this for
17 * the function signatures for functions that are offered as function
18 * pointers in OSSL_DISPATCH arrays.
21 /* Context management */
22 void *OSSL_FUNC_rand_newctx(void *provctx, void *parent,
23 const OSSL_DISPATCH *parent_calls);
24 void OSSL_FUNC_rand_freectx(void *ctx);
26 /* Random number generator functions: NIST */
27 int OSSL_FUNC_rand_instantiate(void *ctx, unsigned int strength,
28 int prediction_resistance,
29 const unsigned char *pstr, size_t pstr_len,
30 const OSSL_PARAM params[]);
31 int OSSL_FUNC_rand_uninstantiate(void *ctx);
32 int OSSL_FUNC_rand_generate(void *ctx, unsigned char *out, size_t outlen,
33 unsigned int strength, int prediction_resistance,
34 const unsigned char *addin, size_t addin_len);
35 int OSSL_FUNC_rand_reseed(void *ctx, int prediction_resistance,
36 const unsigned char *ent, size_t ent_len,
37 const unsigned char *addin, size_t addin_len);
39 /* Random number generator functions: additional */
40 size_t OSSL_FUNC_rand_nonce(void *ctx, unsigned char *out, size_t outlen,
41 int strength, size_t min_noncelen,
43 size_t OSSL_FUNC_rand_get_seed(void *ctx, unsigned char **buffer,
44 int entropy, size_t min_len, size_t max_len,
45 int prediction_resistance,
46 const unsigned char *adin, size_t adin_len);
47 void OSSL_FUNC_rand_clear_seed(void *ctx, unsigned char *buffer, size_t b_len);
48 int OSSL_FUNC_rand_verify_zeroization(void *ctx);
51 int OSSL_FUNC_rand_enable_locking(void *ctx);
52 int OSSL_FUNC_rand_lock(void *ctx);
53 void OSSL_FUNC_rand_unlock(void *ctx);
55 /* RAND parameter descriptors */
56 const OSSL_PARAM *OSSL_FUNC_rand_gettable_params(void *provctx);
57 const OSSL_PARAM *OSSL_FUNC_rand_gettable_ctx_params(void *ctx, void *provctx);
58 const OSSL_PARAM *OSSL_FUNC_rand_settable_ctx_params(void *ctx, void *provctx);
61 int OSSL_FUNC_rand_get_params(OSSL_PARAM params[]);
62 int OSSL_FUNC_rand_get_ctx_params(void *ctx, OSSL_PARAM params[]);
63 int OSSL_FUNC_rand_set_ctx_params(void *ctx, const OSSL_PARAM params[]);
67 This documentation is primarily aimed at provider authors. See L<provider(7)>
68 for further information.
70 The RAND operation enables providers to implement random number generation
71 algorithms and random number sources and make
72 them available to applications via the API function L<EVP_RAND(3)>.
74 =head2 Context Management Functions
76 OSSL_FUNC_rand_newctx() should create and return a pointer to a provider side
77 structure for holding context information during a rand operation.
78 A pointer to this context will be passed back in a number of the other rand
79 operation function calls.
80 The parameter I<provctx> is the provider context generated during provider
81 initialisation (see L<provider(7)>).
82 The parameter I<parent> specifies another rand instance to be used for
83 seeding purposes. If NULL and the specific instance supports it, the
84 operating system will be used for seeding.
85 The parameter I<parent_calls> points to the dispatch table for I<parent>.
86 Thus, the parent need not be from the same provider as the new instance.
88 OSSL_FUNC_rand_freectx() is passed a pointer to the provider side rand context in
89 the I<mctx> parameter.
90 If it receives NULL as I<ctx> value, it should not do anything other than
92 This function should free any resources associated with that context.
94 =head2 Random Number Generator Functions: NIST
96 These functions correspond to those defined in NIST SP 800-90A and SP 800-90C.
98 OSSL_FUNC_rand_instantiate() is used to instantiate the DRBG I<ctx> at a requested
99 security I<strength>. In addition, I<prediction_resistance> can be requested.
100 Additional input I<addin> of length I<addin_len> bytes can optionally
101 be provided. The parameters specified in I<params> configure the DRBG and these
102 should be processed before instantiation.
104 OSSL_FUNC_rand_uninstantiate() is used to uninstantiate the DRBG I<ctx>. After being
105 uninstantiated, a DRBG is unable to produce output until it is instantiated
108 OSSL_FUNC_rand_generate() is used to generate random bytes from the DRBG I<ctx>.
109 It will generate I<outlen> bytes placing them into the buffer pointed to by
110 I<out>. The generated bytes will meet the specified security I<strength> and,
111 if I<prediction_resistance> is true, the bytes will be produced after reseeding
112 from a live entropy source. Additional input I<addin> of length I<addin_len>
113 bytes can optionally be provided.
115 =head2 Random Number Generator Functions: Additional
117 OSSL_FUNC_rand_nonce() is used to generate a nonce of the given I<strength> with a
118 length from I<min_noncelen> to I<max_noncelen>. If the output buffer I<out> is
119 NULL, the length of the nonce should be returned.
121 OSSL_FUNC_rand_get_seed() is used by deterministic generators to obtain their
122 seeding material from their parent. The seed bytes will meet the specified
123 security level of I<entropy> bits and there will be between I<min_len>
124 and I<max_len> inclusive bytes in total. If I<prediction_resistance> is
125 true, the bytes will be produced from a live entropy source. Additional
126 input I<addin> of length I<addin_len> bytes can optionally be provided.
127 A pointer to the seed material is returned in I<*buffer> and this must be
128 freed by a later call to OSSL_FUNC_rand_clear_seed().
130 OSSL_FUNC_rand_clear_seed() frees a seed I<buffer> of length I<b_len> bytes
131 which was previously allocated by OSSL_FUNC_rand_get_seed().
133 OSSL_FUNC_rand_verify_zeroization() is used to determine if the internal state of the
134 DRBG is zero. This capability is mandated by NIST as part of the self
135 tests, it is unlikely to be useful in other circumstances.
137 =head2 Context Locking
139 When DRBGs are used by multiple threads, there must be locking employed to
140 ensure their proper operation. Because locking introduces an overhead, it
141 is disabled by default.
143 OSSL_FUNC_rand_enable_locking() allows locking to be turned on for a DRBG and all of
144 its parent DRBGs. From this call onwards, the DRBG can be used in a thread
147 OSSL_FUNC_rand_lock() is used to lock a DRBG. Once locked, exclusive access
150 OSSL_FUNC_rand_unlock() is used to unlock a DRBG.
152 =head2 Rand Parameters
154 See L<OSSL_PARAM(3)> for further details on the parameters structure used by
157 OSSL_FUNC_rand_get_params() gets details of parameter values associated with the
158 provider algorithm and stores them in I<params>.
160 OSSL_FUNC_rand_set_ctx_params() sets rand parameters associated with the given
161 provider side rand context I<ctx> to I<params>.
162 Any parameter settings are additional to any that were previously set.
163 Passing NULL for I<params> should return true.
165 OSSL_FUNC_rand_get_ctx_params() gets details of currently set parameter values
166 associated with the given provider side rand context I<ctx> and stores them
168 Passing NULL for I<params> should return true.
170 OSSL_FUNC_rand_gettable_params(), OSSL_FUNC_rand_gettable_ctx_params(),
171 and OSSL_FUNC_rand_settable_ctx_params() all return constant B<OSSL_PARAM>
172 arrays as descriptors of the parameters that OSSL_FUNC_rand_get_params(),
173 OSSL_FUNC_rand_get_ctx_params(), and OSSL_FUNC_rand_set_ctx_params()
174 can handle, respectively. OSSL_FUNC_rand_gettable_ctx_params()
175 and OSSL_FUNC_rand_settable_ctx_params() will return the parameters
176 associated with the provider side context I<ctx> in its current state
177 if it is not NULL. Otherwise, they return the parameters associated
178 with the provider side algorithm I<provctx>.
181 Parameters currently recognised by built-in rands are as follows. Not all
182 parameters are relevant to, or are understood by all rands:
186 =item "state" (B<OSSL_RAND_PARAM_STATE>) <integer>
188 Returns the state of the random number generator.
190 =item "strength" (B<OSSL_RAND_PARAM_STRENGTH>) <unsigned integer>
192 Returns the bit strength of the random number generator.
196 For rands that are also deterministic random bit generators (DRBGs), these
197 additional parameters are recognised. Not all
198 parameters are relevant to, or are understood by all DRBG rands:
202 =item "reseed_requests" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer>
204 Reads or set the number of generate requests before reseeding the
207 =item "reseed_time_interval" (B<OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL>) <integer>
209 Reads or set the number of elapsed seconds before reseeding the
212 =item "max_request" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer>
214 Specifies the maximum number of bytes that can be generated in a single
215 call to OSSL_FUNC_rand_generate.
217 =item "min_entropylen" (B<OSSL_DRBG_PARAM_MIN_ENTROPYLEN>) <unsigned integer>
219 =item "max_entropylen" (B<OSSL_DRBG_PARAM_MAX_ENTROPYLEN>) <unsigned integer>
221 Specify the minimum and maximum number of bytes of random material that
222 can be used to seed the DRBG.
224 =item "min_noncelen" (B<OSSL_DRBG_PARAM_MIN_NONCELEN>) <unsigned integer>
226 =item "max_noncelen" (B<OSSL_DRBG_PARAM_MAX_NONCELEN>) <unsigned integer>
228 Specify the minimum and maximum number of bytes of nonce that can be used to
229 instantiate the DRBG.
231 =item "max_perslen" (B<OSSL_DRBG_PARAM_MAX_PERSLEN>) <unsigned integer>
233 =item "max_adinlen" (B<OSSL_DRBG_PARAM_MAX_ADINLEN>) <unsigned integer>
235 Specify the minimum and maximum number of bytes of personalisation string
236 that can be used with the DRBG.
238 =item "reseed_counter" (B<OSSL_DRBG_PARAM_RESEED_COUNTER>) <unsigned integer>
240 Specifies the number of times the DRBG has been seeded or reseeded.
242 =item "digest" (B<OSSL_DRBG_PARAM_DIGEST>) <UTF8 string>
244 =item "cipher" (B<OSSL_DRBG_PARAM_CIPHER>) <UTF8 string>
246 =item "mac" (B<OSSL_DRBG_PARAM_MAC>) <UTF8 string>
248 Sets the name of the underlying cipher, digest or MAC to be used.
249 It must name a suitable algorithm for the DRBG that's being used.
251 =item "properties" (B<OSSL_DRBG_PARAM_PROPERTIES>) <UTF8 string>
253 Sets the properties to be queried when trying to fetch an underlying algorithm.
254 This must be given together with the algorithm naming parameter to be
261 OSSL_FUNC_rand_newctx() should return the newly created
262 provider side rand context, or NULL on failure.
264 OSSL_FUNC_rand_gettable_params(), OSSL_FUNC_rand_gettable_ctx_params() and
265 OSSL_FUNC_rand_settable_ctx_params() should return a constant B<OSSL_PARAM>
266 array, or NULL if none is offered.
268 OSSL_FUNC_rand_nonce() returns the size of the generated nonce, or 0 on error.
270 OSSL_FUNC_rand_get_seed() returns the size of the generated seed, or 0 on
273 All of the remaining functions should return 1 for success or 0 on error.
283 The provider RAND interface was introduced in OpenSSL 3.0.
287 Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
289 Licensed under the Apache License 2.0 (the "License"). You may not use
290 this file except in compliance with the License. You can obtain a copy
291 in the file LICENSE in the source distribution or at
292 L<https://www.openssl.org/source/license.html>.