1=pod 2 3=head1 NAME 4 5EVP_RAND, EVP_RAND_fetch, EVP_RAND_free, EVP_RAND_up_ref, EVP_RAND_CTX, 6EVP_RAND_CTX_new, EVP_RAND_CTX_free, EVP_RAND_instantiate, 7EVP_RAND_uninstantiate, EVP_RAND_generate, EVP_RAND_reseed, EVP_RAND_nonce, 8EVP_RAND_enable_locking, EVP_RAND_verify_zeroization, EVP_RAND_get_strength, 9EVP_RAND_get_state, 10EVP_RAND_get0_provider, EVP_RAND_CTX_get0_rand, EVP_RAND_is_a, 11EVP_RAND_get0_name, EVP_RAND_names_do_all, 12EVP_RAND_get0_description, 13EVP_RAND_CTX_get_params, 14EVP_RAND_CTX_set_params, EVP_RAND_do_all_provided, EVP_RAND_get_params, 15EVP_RAND_gettable_ctx_params, EVP_RAND_settable_ctx_params, 16EVP_RAND_CTX_gettable_params, EVP_RAND_CTX_settable_params, 17EVP_RAND_gettable_params, EVP_RAND_STATE_UNINITIALISED, EVP_RAND_STATE_READY, 18EVP_RAND_STATE_ERROR - EVP RAND routines 19 20=head1 SYNOPSIS 21 22 #include <openssl/evp.h> 23 24 typedef struct evp_rand_st EVP_RAND; 25 typedef struct evp_rand_ctx_st EVP_RAND_CTX; 26 27 EVP_RAND *EVP_RAND_fetch(OSSL_LIB_CTX *libctx, const char *algorithm, 28 const char *properties); 29 int EVP_RAND_up_ref(EVP_RAND *rand); 30 void EVP_RAND_free(EVP_RAND *rand); 31 EVP_RAND_CTX *EVP_RAND_CTX_new(EVP_RAND *rand, EVP_RAND_CTX *parent); 32 void EVP_RAND_CTX_free(EVP_RAND_CTX *ctx); 33 EVP_RAND *EVP_RAND_CTX_get0_rand(EVP_RAND_CTX *ctx); 34 int EVP_RAND_get_params(EVP_RAND *rand, OSSL_PARAM params[]); 35 int EVP_RAND_CTX_get_params(EVP_RAND_CTX *ctx, OSSL_PARAM params[]); 36 int EVP_RAND_CTX_set_params(EVP_RAND_CTX *ctx, const OSSL_PARAM params[]); 37 const OSSL_PARAM *EVP_RAND_gettable_params(const EVP_RAND *rand); 38 const OSSL_PARAM *EVP_RAND_gettable_ctx_params(const EVP_RAND *rand); 39 const OSSL_PARAM *EVP_RAND_settable_ctx_params(const EVP_RAND *rand); 40 const OSSL_PARAM *EVP_RAND_CTX_gettable_params(EVP_RAND_CTX *ctx); 41 const OSSL_PARAM *EVP_RAND_CTX_settable_params(EVP_RAND_CTX *ctx); 42 const char *EVP_RAND_get0_name(const EVP_RAND *rand); 43 const char *EVP_RAND_get0_description(const EVP_RAND *rand); 44 int EVP_RAND_is_a(const EVP_RAND *rand, const char *name); 45 const OSSL_PROVIDER *EVP_RAND_get0_provider(const EVP_RAND *rand); 46 void EVP_RAND_do_all_provided(OSSL_LIB_CTX *libctx, 47 void (*fn)(EVP_RAND *rand, void *arg), 48 void *arg); 49 int EVP_RAND_names_do_all(const EVP_RAND *rand, 50 void (*fn)(const char *name, void *data), 51 void *data); 52 53 int EVP_RAND_instantiate(EVP_RAND_CTX *ctx, unsigned int strength, 54 int prediction_resistance, 55 const unsigned char *pstr, size_t pstr_len, 56 const OSSL_PARAM params[]); 57 int EVP_RAND_uninstantiate(EVP_RAND_CTX *ctx); 58 int EVP_RAND_generate(EVP_RAND_CTX *ctx, unsigned char *out, size_t outlen, 59 unsigned int strength, int prediction_resistance, 60 const unsigned char *addin, size_t addin_len); 61 int EVP_RAND_reseed(EVP_RAND_CTX *ctx, int prediction_resistance, 62 const unsigned char *ent, size_t ent_len, 63 const unsigned char *addin, size_t addin_len); 64 int EVP_RAND_nonce(EVP_RAND_CTX *ctx, unsigned char *out, size_t outlen); 65 int EVP_RAND_enable_locking(EVP_RAND_CTX *ctx); 66 int EVP_RAND_verify_zeroization(EVP_RAND_CTX *ctx); 67 unsigned int EVP_RAND_get_strength(EVP_RAND_CTX *ctx); 68 int EVP_RAND_get_state(EVP_RAND_CTX *ctx); 69 70 #define EVP_RAND_STATE_UNINITIALISED 0 71 #define EVP_RAND_STATE_READY 1 72 #define EVP_RAND_STATE_ERROR 2 73 74=head1 DESCRIPTION 75 76The EVP RAND routines are a high-level interface to random number generators 77both deterministic and not. 78If you just want to generate random bytes then you don't need to use 79these functions: just call RAND_bytes() or RAND_priv_bytes(). 80If you want to do more, these calls should be used instead of the older 81RAND and RAND_DRBG functions. 82 83After creating a B<EVP_RAND_CTX> for the required algorithm using 84EVP_RAND_CTX_new(), inputs to the algorithm are supplied either by 85passing them as part of the EVP_RAND_instantiate() call or using calls to 86EVP_RAND_CTX_set_params() before calling EVP_RAND_instantiate(). Finally, 87call EVP_RAND_generate() to produce cryptographically secure random bytes. 88 89=head2 Types 90 91B<EVP_RAND> is a type that holds the implementation of a RAND. 92 93B<EVP_RAND_CTX> is a context type that holds the algorithm inputs. 94B<EVP_RAND_CTX> structures are reference counted. 95 96=head2 Algorithm implementation fetching 97 98EVP_RAND_fetch() fetches an implementation of a RAND I<algorithm>, given 99a library context I<libctx> and a set of I<properties>. 100See L<crypto(7)/ALGORITHM FETCHING> for further information. 101 102The returned value must eventually be freed with 103L<EVP_RAND_free(3)>. 104 105EVP_RAND_up_ref() increments the reference count of an already fetched 106RAND. 107 108EVP_RAND_free() frees a fetched algorithm. 109NULL is a valid parameter, for which this function is a no-op. 110 111=head2 Context manipulation functions 112 113EVP_RAND_CTX_new() creates a new context for the RAND implementation I<rand>. 114If not NULL, I<parent> specifies the seed source for this implementation. 115Not all random number generators need to have a seed source specified. 116If a parent is required, a NULL I<parent> will utilise the operating 117system entropy sources. 118It is recommended to minimise the number of random number generators that 119rely on the operating system for their randomness because this is often scarce. 120 121EVP_RAND_CTX_free() frees up the context I<ctx>. If I<ctx> is NULL, nothing 122is done. 123 124EVP_RAND_CTX_get0_rand() returns the B<EVP_RAND> associated with the context 125I<ctx>. 126 127=head2 Random Number Generator Functions 128 129EVP_RAND_instantiate() processes any parameters in I<params> and 130then instantiates the RAND I<ctx> with a minimum security strength 131of <strength> and personalisation string I<pstr> of length <pstr_len>. 132If I<prediction_resistance> is specified, fresh entropy from a live source 133will be sought. This call operates as per NIST SP 800-90A and SP 800-90C. 134 135EVP_RAND_uninstantiate() uninstantiates the RAND I<ctx> as per 136NIST SP 800-90A and SP 800-90C. Subsequent to this call, the RAND cannot 137be used to generate bytes. It can only be freed or instantiated again. 138 139EVP_RAND_generate() produces random bytes from the RAND I<ctx> with the 140additional input I<addin> of length I<addin_len>. The bytes 141produced will meet the security I<strength>. 142If I<prediction_resistance> is specified, fresh entropy from a live source 143will be sought. This call operates as per NIST SP 800-90A and SP 800-90C. 144 145EVP_RAND_reseed() reseeds the RAND with new entropy. 146Entropy I<ent> of length I<ent_len> bytes can be supplied as can additional 147input I<addin> of length I<addin_len> bytes. In the FIPS provider, both are 148treated as additional input as per NIST SP-800-90Ar1, Sections 9.1 and 9.2. 149Additional seed material is also drawn from the RAND's parent or the 150operating system. If I<prediction_resistance> is specified, fresh entropy 151from a live source will be sought. This call operates as per NIST SP 800-90A 152and SP 800-90C. 153 154EVP_RAND_nonce() creates a nonce in I<out> of maximum length I<outlen> 155bytes from the RAND I<ctx>. The function returns the length of the generated 156nonce. If I<out> is NULL, the length is still returned but no generation 157takes place. This allows a caller to dynamically allocate a buffer of the 158appropriate size. 159 160EVP_RAND_enable_locking() enables locking for the RAND I<ctx> and all of 161its parents. After this I<ctx> will operate in a thread safe manner, albeit 162more slowly. This function is not itself thread safe if called with the same 163I<ctx> from multiple threads. Typically locking should be enabled before a 164I<ctx> is shared across multiple threads. 165 166EVP_RAND_get_params() retrieves details about the implementation 167I<rand>. 168The set of parameters given with I<params> determine exactly what 169parameters should be retrieved. 170Note that a parameter that is unknown in the underlying context is 171simply ignored. 172 173EVP_RAND_CTX_get_params() retrieves chosen parameters, given the 174context I<ctx> and its underlying context. 175The set of parameters given with I<params> determine exactly what 176parameters should be retrieved. 177Note that a parameter that is unknown in the underlying context is 178simply ignored. 179 180EVP_RAND_CTX_set_params() passes chosen parameters to the underlying 181context, given a context I<ctx>. 182The set of parameters given with I<params> determine exactly what 183parameters are passed down. 184Note that a parameter that is unknown in the underlying context is 185simply ignored. 186Also, what happens when a needed parameter isn't passed down is 187defined by the implementation. 188 189EVP_RAND_gettable_params() returns an B<OSSL_PARAM> array that describes 190the retrievable and settable parameters. EVP_RAND_gettable_params() returns 191parameters that can be used with EVP_RAND_get_params(). See L<OSSL_PARAM(3)> 192for the use of B<OSSL_PARAM> as a parameter descriptor. 193 194EVP_RAND_gettable_ctx_params() and EVP_RAND_CTX_gettable_params() return 195constant B<OSSL_PARAM> arrays that describe the retrievable parameters that 196can be used with EVP_RAND_CTX_get_params(). EVP_RAND_gettable_ctx_params() 197returns the parameters that can be retrieved from the algorithm, whereas 198EVP_RAND_CTX_gettable_params() returns the parameters that can be retrieved 199in the context's current state. See L<OSSL_PARAM(3)> for the use of 200B<OSSL_PARAM> as a parameter descriptor. 201 202EVP_RAND_settable_ctx_params() and EVP_RAND_CTX_settable_params() return 203constant B<OSSL_PARAM> arrays that describe the settable parameters that 204can be used with EVP_RAND_CTX_set_params(). EVP_RAND_settable_ctx_params() 205returns the parameters that can be retrieved from the algorithm, whereas 206EVP_RAND_CTX_settable_params() returns the parameters that can be retrieved 207in the context's current state. See L<OSSL_PARAM(3)> for the use of 208B<OSSL_PARAM> as a parameter descriptor. 209 210=head2 Information functions 211 212EVP_RAND_get_strength() returns the security strength of the RAND I<ctx>. 213 214EVP_RAND_get_state() returns the current state of the RAND I<ctx>. 215States defined by the OpenSSL RNGs are: 216 217=over 4 218 219=item * 220 221EVP_RAND_STATE_UNINITIALISED: this RNG is currently uninitialised. 222The instantiate call will change this to the ready state. 223 224=item * 225 226EVP_RAND_STATE_READY: this RNG is currently ready to generate output. 227 228=item * 229 230EVP_RAND_STATE_ERROR: this RNG is in an error state. 231 232=back 233 234EVP_RAND_is_a() returns 1 if I<rand> is an implementation of an 235algorithm that's identifiable with I<name>, otherwise 0. 236 237EVP_RAND_get0_provider() returns the provider that holds the implementation 238of the given I<rand>. 239 240EVP_RAND_do_all_provided() traverses all RAND implemented by all activated 241providers in the given library context I<libctx>, and for each of the 242implementations, calls the given function I<fn> with the implementation method 243and the given I<arg> as argument. 244 245EVP_RAND_get0_name() returns the canonical name of I<rand>. 246 247EVP_RAND_names_do_all() traverses all names for I<rand>, and calls 248I<fn> with each name and I<data>. 249 250EVP_RAND_get0_description() returns a description of the rand, meant for 251display and human consumption. The description is at the discretion of 252the rand implementation. 253 254EVP_RAND_verify_zeroization() confirms if the internal DRBG state is 255currently zeroed. This is used by the FIPS provider to support the mandatory 256self tests. 257 258=head1 PARAMETERS 259 260The standard parameter names are: 261 262=over 4 263 264=item "state" (B<OSSL_RAND_PARAM_STATE>) <integer> 265 266Returns the state of the random number generator. 267 268=item "strength" (B<OSSL_RAND_PARAM_STRENGTH>) <unsigned integer> 269 270Returns the bit strength of the random number generator. 271 272=back 273 274For rands that are also deterministic random bit generators (DRBGs), these 275additional parameters are recognised. Not all 276parameters are relevant to, or are understood by all DRBG rands: 277 278=over 4 279 280=item "reseed_requests" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer> 281 282Reads or set the number of generate requests before reseeding the 283associated RAND ctx. 284 285=item "reseed_time_interval" (B<OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL>) <integer> 286 287Reads or set the number of elapsed seconds before reseeding the 288associated RAND ctx. 289 290=item "max_request" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer> 291 292Specifies the maximum number of bytes that can be generated in a single 293call to OSSL_FUNC_rand_generate. 294 295=item "min_entropylen" (B<OSSL_DRBG_PARAM_MIN_ENTROPYLEN>) <unsigned integer> 296 297=item "max_entropylen" (B<OSSL_DRBG_PARAM_MAX_ENTROPYLEN>) <unsigned integer> 298 299Specify the minimum and maximum number of bytes of random material that 300can be used to seed the DRBG. 301 302=item "min_noncelen" (B<OSSL_DRBG_PARAM_MIN_NONCELEN>) <unsigned integer> 303 304=item "max_noncelen" (B<OSSL_DRBG_PARAM_MAX_NONCELEN>) <unsigned integer> 305 306Specify the minimum and maximum number of bytes of nonce that can be used to 307seed the DRBG. 308 309=item "max_perslen" (B<OSSL_DRBG_PARAM_MAX_PERSLEN>) <unsigned integer> 310 311=item "max_adinlen" (B<OSSL_DRBG_PARAM_MAX_ADINLEN>) <unsigned integer> 312 313Specify the minimum and maximum number of bytes of personalisation string 314that can be used with the DRBG. 315 316=item "reseed_counter" (B<OSSL_DRBG_PARAM_RESEED_COUNTER>) <unsigned integer> 317 318Specifies the number of times the DRBG has been seeded or reseeded. 319 320=item "properties" (B<OSSL_RAND_PARAM_PROPERTIES>) <UTF8 string> 321 322=item "mac" (B<OSSL_RAND_PARAM_MAC>) <UTF8 string> 323 324=item "digest" (B<OSSL_RAND_PARAM_DIGEST>) <UTF8 string> 325 326=item "cipher" (B<OSSL_RAND_PARAM_CIPHER>) <UTF8 string> 327 328For RAND implementations that use an underlying computation MAC, digest or 329cipher, these parameters set what the algorithm should be. 330 331The value is always the name of the intended algorithm, 332or the properties in the case of B<OSSL_RAND_PARAM_PROPERTIES>. 333 334=back 335 336=head1 NOTES 337 338An B<EVP_RAND_CTX> needs to have locking enabled if it acts as the parent of 339more than one child and the children can be accessed concurrently. This must 340be done by explicitly calling EVP_RAND_enable_locking(). 341 342The RAND life-cycle is described in L<life_cycle-rand(7)>. In the future, 343the transitions described there will be enforced. When this is done, it will 344not be considered a breaking change to the API. 345 346=head1 RETURN VALUES 347 348EVP_RAND_fetch() returns a pointer to a newly fetched B<EVP_RAND>, or 349NULL if allocation failed. 350 351EVP_RAND_get0_provider() returns a pointer to the provider for the RAND, or 352NULL on error. 353 354EVP_RAND_CTX_get0_rand() returns a pointer to the B<EVP_RAND> associated 355with the context. 356 357EVP_RAND_get0_name() returns the name of the random number generation 358algorithm. 359 360EVP_RAND_up_ref() returns 1 on success, 0 on error. 361 362EVP_RAND_names_do_all() returns 1 if the callback was called for all names. A 363return value of 0 means that the callback was not called for any names. 364 365EVP_RAND_CTX_new() returns either the newly allocated 366B<EVP_RAND_CTX> structure or NULL if an error occurred. 367 368EVP_RAND_CTX_free() does not return a value. 369 370EVP_RAND_nonce() returns the length of the nonce. 371 372EVP_RAND_get_strength() returns the strength of the random number generator 373in bits. 374 375EVP_RAND_gettable_params(), EVP_RAND_gettable_ctx_params() and 376EVP_RAND_settable_ctx_params() return an array of OSSL_PARAMs. 377 378EVP_RAND_verify_zeroization() returns 1 if the internal DRBG state is 379currently zeroed, and 0 if not. 380 381The remaining functions return 1 for success and 0 or a negative value for 382failure. 383 384=head1 SEE ALSO 385 386L<RAND_bytes(3)>, 387L<EVP_RAND-CTR-DRBG(7)>, 388L<EVP_RAND-HASH-DRBG(7)>, 389L<EVP_RAND-HMAC-DRBG(7)>, 390L<EVP_RAND-TEST-RAND(7)>, 391L<provider-rand(7)>, 392L<life_cycle-rand(7)> 393 394=head1 HISTORY 395 396This functionality was added to OpenSSL 3.0. 397 398=head1 COPYRIGHT 399 400Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved. 401 402Licensed under the Apache License 2.0 (the "License"). You may not use 403this file except in compliance with the License. You can obtain a copy 404in the file LICENSE in the source distribution or at 405L<https://www.openssl.org/source/license.html>. 406 407=cut 408