1=pod 2 3=head1 NAME 4 5provider-rand - The random number generation library E<lt>-E<gt> provider 6functions 7 8=head1 SYNOPSIS 9 10=for openssl multiple includes 11 12 #include <openssl/core_dispatch.h> 13 #include <openssl/core_names.h> 14 15 /* 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. 19 */ 20 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); 25 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); 38 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, 42 size_t max_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); 49 50 /* Context Locking */ 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); 54 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); 59 60 /* RAND parameters */ 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[]); 64 65=head1 DESCRIPTION 66 67This documentation is primarily aimed at provider authors. See L<provider(7)> 68for further information. 69 70The RAND operation enables providers to implement random number generation 71algorithms and random number sources and make 72them available to applications via the API function L<EVP_RAND(3)>. 73 74=head2 Context Management Functions 75 76OSSL_FUNC_rand_newctx() should create and return a pointer to a provider side 77structure for holding context information during a rand operation. 78A pointer to this context will be passed back in a number of the other rand 79operation function calls. 80The parameter I<provctx> is the provider context generated during provider 81initialisation (see L<provider(7)>). 82The parameter I<parent> specifies another rand instance to be used for 83seeding purposes. If NULL and the specific instance supports it, the 84operating system will be used for seeding. 85The parameter I<parent_calls> points to the dispatch table for I<parent>. 86Thus, the parent need not be from the same provider as the new instance. 87 88OSSL_FUNC_rand_freectx() is passed a pointer to the provider side rand context in 89the I<mctx> parameter. 90If it receives NULL as I<ctx> value, it should not do anything other than 91return. 92This function should free any resources associated with that context. 93 94=head2 Random Number Generator Functions: NIST 95 96These functions correspond to those defined in NIST SP 800-90A and SP 800-90C. 97 98OSSL_FUNC_rand_instantiate() is used to instantiate the DRBG I<ctx> at a requested 99security I<strength>. In addition, I<prediction_resistance> can be requested. 100Additional input I<addin> of length I<addin_len> bytes can optionally 101be provided. The parameters specified in I<params> configure the DRBG and these 102should be processed before instantiation. 103 104OSSL_FUNC_rand_uninstantiate() is used to uninstantiate the DRBG I<ctx>. After being 105uninstantiated, a DRBG is unable to produce output until it is instantiated 106anew. 107 108OSSL_FUNC_rand_generate() is used to generate random bytes from the DRBG I<ctx>. 109It will generate I<outlen> bytes placing them into the buffer pointed to by 110I<out>. The generated bytes will meet the specified security I<strength> and, 111if I<prediction_resistance> is true, the bytes will be produced after reseeding 112from a live entropy source. Additional input I<addin> of length I<addin_len> 113bytes can optionally be provided. 114 115=head2 Random Number Generator Functions: Additional 116 117OSSL_FUNC_rand_nonce() is used to generate a nonce of the given I<strength> with a 118length from I<min_noncelen> to I<max_noncelen>. If the output buffer I<out> is 119NULL, the length of the nonce should be returned. 120 121OSSL_FUNC_rand_get_seed() is used by deterministic generators to obtain their 122seeding material from their parent. The seed bytes will meet the specified 123security level of I<entropy> bits and there will be between I<min_len> 124and I<max_len> inclusive bytes in total. If I<prediction_resistance> is 125true, the bytes will be produced from a live entropy source. Additional 126input I<addin> of length I<addin_len> bytes can optionally be provided. 127A pointer to the seed material is returned in I<*buffer> and this must be 128freed by a later call to OSSL_FUNC_rand_clear_seed(). 129 130OSSL_FUNC_rand_clear_seed() frees a seed I<buffer> of length I<b_len> bytes 131which was previously allocated by OSSL_FUNC_rand_get_seed(). 132 133OSSL_FUNC_rand_verify_zeroization() is used to determine if the internal state of the 134DRBG is zero. This capability is mandated by NIST as part of the self 135tests, it is unlikely to be useful in other circumstances. 136 137=head2 Context Locking 138 139When DRBGs are used by multiple threads, there must be locking employed to 140ensure their proper operation. Because locking introduces an overhead, it 141is disabled by default. 142 143OSSL_FUNC_rand_enable_locking() allows locking to be turned on for a DRBG and all of 144its parent DRBGs. From this call onwards, the DRBG can be used in a thread 145safe manner. 146 147OSSL_FUNC_rand_lock() is used to lock a DRBG. Once locked, exclusive access 148is guaranteed. 149 150OSSL_FUNC_rand_unlock() is used to unlock a DRBG. 151 152=head2 Rand Parameters 153 154See L<OSSL_PARAM(3)> for further details on the parameters structure used by 155these functions. 156 157OSSL_FUNC_rand_get_params() gets details of parameter values associated with the 158provider algorithm and stores them in I<params>. 159 160OSSL_FUNC_rand_set_ctx_params() sets rand parameters associated with the given 161provider side rand context I<ctx> to I<params>. 162Any parameter settings are additional to any that were previously set. 163Passing NULL for I<params> should return true. 164 165OSSL_FUNC_rand_get_ctx_params() gets details of currently set parameter values 166associated with the given provider side rand context I<ctx> and stores them 167in I<params>. 168Passing NULL for I<params> should return true. 169 170OSSL_FUNC_rand_gettable_params(), OSSL_FUNC_rand_gettable_ctx_params(), 171and OSSL_FUNC_rand_settable_ctx_params() all return constant L<OSSL_PARAM(3)> 172arrays as descriptors of the parameters that OSSL_FUNC_rand_get_params(), 173OSSL_FUNC_rand_get_ctx_params(), and OSSL_FUNC_rand_set_ctx_params() 174can handle, respectively. OSSL_FUNC_rand_gettable_ctx_params() 175and OSSL_FUNC_rand_settable_ctx_params() will return the parameters 176associated with the provider side context I<ctx> in its current state 177if it is not NULL. Otherwise, they return the parameters associated 178with the provider side algorithm I<provctx>. 179 180 181Parameters currently recognised by built-in rands are as follows. Not all 182parameters are relevant to, or are understood by all rands: 183 184=over 4 185 186=item "state" (B<OSSL_RAND_PARAM_STATE>) <integer> 187 188Returns the state of the random number generator. 189 190=item "strength" (B<OSSL_RAND_PARAM_STRENGTH>) <unsigned integer> 191 192Returns the bit strength of the random number generator. 193 194=back 195 196For rands that are also deterministic random bit generators (DRBGs), these 197additional parameters are recognised. Not all 198parameters are relevant to, or are understood by all DRBG rands: 199 200=over 4 201 202=item "reseed_requests" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer> 203 204Reads or set the number of generate requests before reseeding the 205associated RAND ctx. 206 207=item "reseed_time_interval" (B<OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL>) <integer> 208 209Reads or set the number of elapsed seconds before reseeding the 210associated RAND ctx. 211 212=item "max_request" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer> 213 214Specifies the maximum number of bytes that can be generated in a single 215call to OSSL_FUNC_rand_generate. 216 217=item "min_entropylen" (B<OSSL_DRBG_PARAM_MIN_ENTROPYLEN>) <unsigned integer> 218 219=item "max_entropylen" (B<OSSL_DRBG_PARAM_MAX_ENTROPYLEN>) <unsigned integer> 220 221Specify the minimum and maximum number of bytes of random material that 222can be used to seed the DRBG. 223 224=item "min_noncelen" (B<OSSL_DRBG_PARAM_MIN_NONCELEN>) <unsigned integer> 225 226=item "max_noncelen" (B<OSSL_DRBG_PARAM_MAX_NONCELEN>) <unsigned integer> 227 228Specify the minimum and maximum number of bytes of nonce that can be used to 229instantiate the DRBG. 230 231=item "max_perslen" (B<OSSL_DRBG_PARAM_MAX_PERSLEN>) <unsigned integer> 232 233=item "max_adinlen" (B<OSSL_DRBG_PARAM_MAX_ADINLEN>) <unsigned integer> 234 235Specify the minimum and maximum number of bytes of personalisation string 236that can be used with the DRBG. 237 238=item "reseed_counter" (B<OSSL_DRBG_PARAM_RESEED_COUNTER>) <unsigned integer> 239 240Specifies the number of times the DRBG has been seeded or reseeded. 241 242=item "digest" (B<OSSL_DRBG_PARAM_DIGEST>) <UTF8 string> 243 244=item "cipher" (B<OSSL_DRBG_PARAM_CIPHER>) <UTF8 string> 245 246=item "mac" (B<OSSL_DRBG_PARAM_MAC>) <UTF8 string> 247 248Sets the name of the underlying cipher, digest or MAC to be used. 249It must name a suitable algorithm for the DRBG that's being used. 250 251=item "properties" (B<OSSL_DRBG_PARAM_PROPERTIES>) <UTF8 string> 252 253Sets the properties to be queried when trying to fetch an underlying algorithm. 254This must be given together with the algorithm naming parameter to be 255considered valid. 256 257=back 258 259=head1 RETURN VALUES 260 261OSSL_FUNC_rand_newctx() should return the newly created 262provider side rand context, or NULL on failure. 263 264OSSL_FUNC_rand_gettable_params(), OSSL_FUNC_rand_gettable_ctx_params() and 265OSSL_FUNC_rand_settable_ctx_params() should return a constant L<OSSL_PARAM(3)> 266array, or NULL if none is offered. 267 268OSSL_FUNC_rand_nonce() returns the size of the generated nonce, or 0 on error. 269 270OSSL_FUNC_rand_get_seed() returns the size of the generated seed, or 0 on 271error. 272 273All of the remaining functions should return 1 for success or 0 on error. 274 275=head1 NOTES 276 277The RAND life-cycle is described in L<life_cycle-rand(7)>. Providers should 278ensure that the various transitions listed there are supported. At some point 279the EVP layer will begin enforcing the listed transitions. 280 281=head1 SEE ALSO 282 283L<provider(7)>, 284L<RAND(7)>, 285L<EVP_RAND(7)>, 286L<life_cycle-rand(7)>, 287L<EVP_RAND(3)> 288 289=head1 HISTORY 290 291The provider RAND interface was introduced in OpenSSL 3.0. 292 293=head1 COPYRIGHT 294 295Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved. 296 297Licensed under the Apache License 2.0 (the "License"). You may not use 298this file except in compliance with the License. You can obtain a copy 299in the file LICENSE in the source distribution or at 300L<https://www.openssl.org/source/license.html>. 301 302=cut 303