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 int OSSL_FUNC_rand_uninstantiate(void *ctx);
31 int OSSL_FUNC_rand_generate(void *ctx, unsigned char *out, size_t outlen,
32 unsigned int strength, int prediction_resistance,
33 const unsigned char *addin, size_t addin_len);
34 int OSSL_FUNC_rand_reseed(void *ctx, int prediction_resistance,
35 const unsigned char *ent, size_t ent_len,
36 const unsigned char *addin, size_t addin_len);
38 /* Random number generator functions: additional */
39 size_t OSSL_FUNC_rand_nonce(void *ctx, unsigned char *out, size_t outlen,
40 int strength, size_t min_noncelen, size_t max_noncelen);
41 void OSSL_FUNC_rand_set_callbacks(void *ctx, OSSL_CALLBACK *get_entropy,
42 OSSL_CALLBACK *cleanup_entropy,
43 OSSL_CALLBACK *get_nonce,
44 OSSL_CALLBACK *cleanup_nonce, void *arg);
45 int OSSL_FUNC_rand_verify_zeroization(void *ctx);
48 int OSSL_FUNC_rand_enable_locking(void *ctx);
49 int OSSL_FUNC_rand_lock(void *ctx);
50 void OSSL_FUNC_rand_unlock(void *ctx);
52 /* RAND parameter descriptors */
53 const OSSL_PARAM *OSSL_FUNC_rand_gettable_params(void);
54 const OSSL_PARAM *OSSL_FUNC_rand_gettable_ctx_params(void);
55 const OSSL_PARAM *OSSL_FUNC_rand_settable_ctx_params(void);
58 int OSSL_FUNC_rand_get_params(OSSL_PARAM params[]);
59 int OSSL_FUNC_rand_get_ctx_params(void *ctx, OSSL_PARAM params[]);
60 int OSSL_FUNC_rand_set_ctx_params(void *ctx, const OSSL_PARAM params[]);
64 This documentation is primarily aimed at provider authors. See L<provider(7)>
65 for further information.
67 The RAND operation enables providers to implement random number generation
68 algorithms and random number sources and make
69 them available to applications via the API function L<EVP_RAND(3)>.
71 =head2 Context Management Functions
73 OSSL_FUNC_rand_newctx() should create and return a pointer to a provider side
74 structure for holding context information during a rand operation.
75 A pointer to this context will be passed back in a number of the other rand
76 operation function calls.
77 The parameter I<provctx> is the provider context generated during provider
78 initialisation (see L<provider(7)>).
79 The parameter I<parent> specifies another rand instance to be used for
80 seeding purposes. If NULL and the specific instance supports it, the
81 operating system will be used for seeding.
82 The parameter I<parent_calls> points to the dispatch table for I<parent>.
83 Thus, the parent need not be from the same provider as the new instance.
85 OSSL_FUNC_rand_freectx() is passed a pointer to the provider side rand context in
86 the I<mctx> parameter.
87 If it receives NULL as I<ctx> value, it should not do anything other than
89 This function should free any resources associated with that context.
91 =head2 Random Number Generator Functions: NIST
93 These functions correspond to those defined in NIST SP 800-90A and SP 800-90C.
95 OSSL_FUNC_rand_instantiate() is used to instantiate the DRBG I<ctx> at a requested
96 security I<strength>. In addition, I<prediction_resistance> can be requested.
97 Additional input I<addin> of length I<addin_len> bytes can optionally
100 OSSL_FUNC_rand_uninstantiate() is used to uninstantiate the DRBG I<ctx>. After being
101 uninstantiated, a DRBG is unable to produce output until it is instantiated
104 OSSL_FUNC_rand_generate() is used to generate random bytes from the DRBG I<ctx>.
105 It will generate I<outlen> bytes placing them into the buffer pointed to by
106 I<out>. The generated bytes will meet the specified security I<strength> and,
107 if I<prediction_resistance> is true, the bytes will be produced after reseeding
108 from a live entropy source. Additional input I<addin> of length I<addin_len>
109 bytes can optionally be provided.
111 =head2 Random Number Generator Functions: Additional
113 OSSL_FUNC_rand_nonce() is used to generate a nonce of the given I<strength> with a
114 length from I<min_noncelen> to I<max_noncelen>. If the output buffer I<out> is
115 NULL, the length of the nonce should be returned.
117 OSSL_FUNC_rand_set_callbacks() is used to supply custom entropy and nonce callbacks.
118 Instead of gathering seed material from its usual sources, the DRBG I<ctx>
119 should call these functions.
120 The I<get_entropy> and I<cleanup_entropy> callbacks obtain and release bytes
122 The I<get_nonce> and I<cleanup_nonce> functions obtain and release nonce bytes.
123 In all cases, the additional argument I<arg> is passed to the callbacks.
125 OSSL_FUNC_rand_verify_zeroization() is used to determine if the internal state of the
126 DRBG is zero. This capability is mandated by NIST as part of the self
127 tests, it is unlikely to be useful in other circumstances.
129 =head2 Context Locking
131 When DRBGs are used by multiple threads, there must be locking employed to
132 ensure their proper operation. Because locking introduces an overhead, it
133 is disabled by default.
135 OSSL_FUNC_rand_enable_locking() allows locking to be turned on for a DRBG and all of
136 its parent DRBGs. From this call onwards, the DRBG can be used in a thread
139 OSSL_FUNC_rand_lock() is used to lock a DRBG. Once locked, exclusive access
142 OSSL_FUNC_rand_unlock() is used to unlock a DRBG.
144 =head2 Rand Parameters
146 See L<OSSL_PARAM(3)> for further details on the parameters structure used by
149 OSSL_FUNC_rand_get_params() gets details of parameter values associated with the
150 provider algorithm and stores them in I<params>.
152 OSSL_FUNC_rand_set_ctx_params() sets rand parameters associated with the given
153 provider side rand context I<ctx> to I<params>.
154 Any parameter settings are additional to any that were previously set.
156 OSSL_FUNC_rand_get_ctx_params() gets details of currently set parameter values
157 associated with the given provider side rand context I<ctx> and stores them
160 OSSL_FUNC_rand_gettable_params(), OSSL_FUNC_rand_gettable_ctx_params(), and
161 OSSL_FUNC_rand_settable_ctx_params() all return constant B<OSSL_PARAM> arrays
162 as descriptors of the parameters that OSSL_FUNC_rand_get_params(),
163 OSSL_FUNC_rand_get_ctx_params(), and OSSL_FUNC_rand_set_ctx_params() can handle,
166 Parameters currently recognised by built-in rands are as follows. Not all
167 parameters are relevant to, or are understood by all rands:
171 =item "state" (B<OSSL_RAND_PARAM_STATE>) <integer>
173 Returns the state of the random number generator.
175 =item "strength" (B<OSSL_RAND_PARAM_STRENGTH>) <unsigned integer>
177 Returns the bit strength of the random number generator.
181 For rands that are also deterministic random bit generators (DRBGs), these
182 additional parameters are recognised. Not all
183 parameters are relevant to, or are understood by all DRBG rands:
187 =item "reseed_requests" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer>
189 Reads or set the number of generate requests before reseeding the
192 =item "reseed_time_interval" (B<OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL>) <integer>
194 Reads or set the number of elapsed seconds before reseeding the
197 =item "max_request" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer>
199 Specifies the maximum number of bytes that can be generated in a single
200 call to OSSL_FUNC_rand_generate.
202 =item "min_entropylen" (B<OSSL_DRBG_PARAM_MIN_ENTROPYLEN>) <unsigned integer>
204 =item "max_entropylen" (B<OSSL_DRBG_PARAM_MAX_ENTROPYLEN>) <unsigned integer>
206 Specify the minimum and maximum number of bytes of random material that
207 can be used to seed the DRBG.
209 =item "min_noncelen" (B<OSSL_DRBG_PARAM_MIN_NONCELEN>) <unsigned integer>
211 =item "max_noncelen" (B<OSSL_DRBG_PARAM_MAX_NONCELEN>) <unsigned integer>
213 Specify the minimum and maximum number of bytes of nonce that can be used to
214 instantiate the DRBG.
216 =item "max_perslen" (B<OSSL_DRBG_PARAM_MAX_PERSLEN>) <unsigned integer>
218 =item "max_adinlen" (B<OSSL_DRBG_PARAM_MAX_ADINLEN>) <unsigned integer>
220 Specify the minimum and maximum number of bytes of personalisation string
221 that can be used with the DRBG.
223 =item "reseed_counter" (B<OSSL_DRBG_PARAM_RESEED_CTR>) <unsigned integer>
225 Specifies the number of times the DRBG has been seeded or reseeded.
227 =item "digest" (B<OSSL_DRBG_PARAM_DIGEST>) <UTF8 string>
229 =item "cipher" (B<OSSL_DRBG_PARAM_CIPHER>) <UTF8 string>
231 =item "mac" (B<OSSL_DRBG_PARAM_MAC>) <UTF8 string>
233 Sets the name of the underlying cipher, digest or MAC to be used.
234 It must name a suitable algorithm for the DRBG that's being used.
236 =item "properties" (B<OSSL_DRBG_PARAM_PROPERTIES>) <UTF8 string>
238 Sets the properties to be queried when trying to fetch an underlying algorithm.
239 This must be given together with the algorithm naming parameter to be
246 OSSL_FUNC_rand_newctx() should return the newly created
247 provider side rand context, or NULL on failure.
249 OSSL_FUNC_rand_gettable_params(), OSSL_FUNC_rand_gettable_ctx_params() and
250 OSSL_FUNC_rand_settable_ctx_params() should return a constant B<OSSL_PARAM>
251 array, or NULL if none is offered.
253 OSSL_FUNC_rand_nonce() returns the size of the generated nonce, or 0 on error.
255 All of the remaining functions should return 1 for success or 0 on error.
265 The provider RAND interface was introduced in OpenSSL 3.0.
269 Copyright 2020 The OpenSSL Project Authors. All Rights Reserved.
271 Licensed under the Apache License 2.0 (the "License"). You may not use
272 this file except in compliance with the License. You can obtain a copy
273 in the file LICENSE in the source distribution or at
274 L<https://www.openssl.org/source/license.html>.