PROVIDER-RAND(7SSL) OpenSSL PROVIDER-RAND(7SSL)
NAME
provider-rand - The random number generation library <-> provider
functions
SYNOPSIS
#include <openssl/core_dispatch.h>
#include <openssl/core_names.h>
/*
* None of these are actual functions, but are displayed like this for
* the function signatures for functions that are offered as function
* pointers in OSSL_DISPATCH arrays.
*/
/* Context management */
void *OSSL_FUNC_rand_newctx(void *provctx, void *parent,
const OSSL_DISPATCH *parent_calls);
void OSSL_FUNC_rand_freectx(void *ctx);
/* Random number generator functions: NIST */
int OSSL_FUNC_rand_instantiate(void *ctx, unsigned int strength,
int prediction_resistance,
const unsigned char *pstr, size_t pstr_len,
const OSSL_PARAM params[]);
int OSSL_FUNC_rand_uninstantiate(void *ctx);
int OSSL_FUNC_rand_generate(void *ctx, unsigned char *out, size_t outlen,
unsigned int strength, int prediction_resistance,
const unsigned char *addin, size_t addin_len);
int OSSL_FUNC_rand_reseed(void *ctx, int prediction_resistance,
const unsigned char *ent, size_t ent_len,
const unsigned char *addin, size_t addin_len);
/* Random number generator functions: additional */
size_t OSSL_FUNC_rand_nonce(void *ctx, unsigned char *out, size_t outlen,
int strength, size_t min_noncelen,
size_t max_noncelen);
size_t OSSL_FUNC_rand_get_seed(void *ctx, unsigned char **buffer,
int entropy, size_t min_len, size_t max_len,
int prediction_resistance,
const unsigned char *adin, size_t adin_len);
void OSSL_FUNC_rand_clear_seed(void *ctx, unsigned char *buffer, size_t b_len);
int OSSL_FUNC_rand_verify_zeroization(void *ctx);
/* Context Locking */
int OSSL_FUNC_rand_enable_locking(void *ctx);
int OSSL_FUNC_rand_lock(void *ctx);
void OSSL_FUNC_rand_unlock(void *ctx);
/* RAND parameter descriptors */
const OSSL_PARAM *OSSL_FUNC_rand_gettable_params(void *provctx);
const OSSL_PARAM *OSSL_FUNC_rand_gettable_ctx_params(void *ctx, void *provctx);
const OSSL_PARAM *OSSL_FUNC_rand_settable_ctx_params(void *ctx, void *provctx);
/* RAND parameters */
int OSSL_FUNC_rand_get_params(OSSL_PARAM params[]);
int OSSL_FUNC_rand_get_ctx_params(void *ctx, OSSL_PARAM params[]);
int OSSL_FUNC_rand_set_ctx_params(void *ctx, const OSSL_PARAM params[]);
DESCRIPTION
This documentation is primarily aimed at provider authors. See
provider(7) for further information.
The RAND operation enables providers to implement random number
generation algorithms and random number sources and make them available
to applications via the API function EVP_RAND(3).
Context Management Functions
OSSL_FUNC_rand_newctx() should create and return a pointer to a provider
side structure for holding context information during a rand operation.
A pointer to this context will be passed back in a number of the other
rand operation function calls. The parameter provctx is the provider
context generated during provider initialisation (see provider(7)). The
parameter parent specifies another rand instance to be used for seeding
purposes. If NULL and the specific instance supports it, the operating
system will be used for seeding. The parameter parent_calls points to
the dispatch table for parent. Thus, the parent need not be from the
same provider as the new instance.
OSSL_FUNC_rand_freectx() is passed a pointer to the provider side rand
context in the mctx parameter. If it receives NULL as ctx value, it
should not do anything other than return. This function should free any
resources associated with that context.
Random Number Generator Functions: NIST
These functions correspond to those defined in NIST SP 800-90A and SP
800-90C.
OSSL_FUNC_rand_instantiate() is used to instantiate the DRBG ctx at a
requested security strength. In addition, prediction_resistance can be
requested. Additional input addin of length addin_len bytes can
optionally be provided. The parameters specified in params configure
the DRBG and these should be processed before instantiation.
OSSL_FUNC_rand_uninstantiate() is used to uninstantiate the DRBG ctx.
After being uninstantiated, a DRBG is unable to produce output until it
is instantiated anew.
OSSL_FUNC_rand_generate() is used to generate random bytes from the DRBG
ctx. It will generate outlen bytes placing them into the buffer pointed
to by out. The generated bytes will meet the specified security
strength and, if prediction_resistance is true, the bytes will be
produced after reseeding from a live entropy source. Additional input
addin of length addin_len bytes can optionally be provided.
Random Number Generator Functions: Additional
OSSL_FUNC_rand_nonce() is used to generate a nonce of the given strength
with a length from min_noncelen to max_noncelen. If the output buffer
out is NULL, the length of the nonce should be returned.
OSSL_FUNC_rand_get_seed() is used by deterministic generators to obtain
their seeding material from their parent. The seed bytes will meet the
specified security level of entropy bits and there will be between
min_len and max_len inclusive bytes in total. If prediction_resistance
is true, the bytes will be produced from a live entropy source.
Additional input addin of length addin_len bytes can optionally be
provided. A pointer to the seed material is returned in *buffer and
this must be freed by a later call to OSSL_FUNC_rand_clear_seed().
OSSL_FUNC_rand_clear_seed() frees a seed buffer of length b_len bytes
which was previously allocated by OSSL_FUNC_rand_get_seed().
OSSL_FUNC_rand_verify_zeroization() is used to determine if the internal
state of the DRBG is zero. This capability is mandated by NIST as part
of the self tests, it is unlikely to be useful in other circumstances.
Context Locking
When DRBGs are used by multiple threads, there must be locking employed
to ensure their proper operation. Because locking introduces an
overhead, it is disabled by default.
OSSL_FUNC_rand_enable_locking() allows locking to be turned on for a
DRBG and all of its parent DRBGs. From this call onwards, the DRBG can
be used in a thread safe manner.
OSSL_FUNC_rand_lock() is used to lock a DRBG. Once locked, exclusive
access is guaranteed.
OSSL_FUNC_rand_unlock() is used to unlock a DRBG.
Rand Parameters
See OSSL_PARAM(3) for further details on the parameters structure used
by these functions.
OSSL_FUNC_rand_get_params() gets details of parameter values associated
with the provider algorithm and stores them in params.
OSSL_FUNC_rand_set_ctx_params() sets rand parameters associated with the
given provider side rand context ctx to params. Any parameter settings
are additional to any that were previously set. Passing NULL for params
should return true.
OSSL_FUNC_rand_get_ctx_params() gets details of currently set parameter
values associated with the given provider side rand context ctx and
stores them in params. Passing NULL for params should return true.
OSSL_FUNC_rand_gettable_params(), OSSL_FUNC_rand_gettable_ctx_params(),
and OSSL_FUNC_rand_settable_ctx_params() all return constant
OSSL_PARAM(3) arrays as descriptors of the parameters that
OSSL_FUNC_rand_get_params(), OSSL_FUNC_rand_get_ctx_params(), and
OSSL_FUNC_rand_set_ctx_params() can handle, respectively.
OSSL_FUNC_rand_gettable_ctx_params() and
OSSL_FUNC_rand_settable_ctx_params() will return the parameters
associated with the provider side context ctx in its current state if it
is not NULL. Otherwise, they return the parameters associated with the
provider side algorithm provctx.
Parameters currently recognised by built-in rands are as follows. Not
all parameters are relevant to, or are understood by all rands:
"state" (OSSL_RAND_PARAM_STATE) <integer>
Returns the state of the random number generator.
"strength" (OSSL_RAND_PARAM_STRENGTH) <unsigned integer>
Returns the bit strength of the random number generator.
"fips-indicator" (OSSL_RAND_PARAM_FIPS_APPROVED_INDICATOR) <integer>
A getter that returns 1 if the operation is FIPS approved, or 0
otherwise. This option is used by the OpenSSL FIPS provider and is
not supported by all EVP_RAND sources.
For rands that are also deterministic random bit generators (DRBGs),
these additional parameters are recognised. Not all parameters are
relevant to, or are understood by all DRBG rands:
"reseed_requests" (OSSL_DRBG_PARAM_RESEED_REQUESTS) <unsigned integer>
Reads or set the number of generate requests before reseeding the
associated RAND ctx.
"reseed_time_interval" (OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL) <integer>
Reads or set the number of elapsed seconds before reseeding the
associated RAND ctx.
"max_request" (OSSL_DRBG_PARAM_RESEED_REQUESTS) <unsigned integer>
Specifies the maximum number of bytes that can be generated in a
single call to OSSL_FUNC_rand_generate.
"min_entropylen" (OSSL_DRBG_PARAM_MIN_ENTROPYLEN) <unsigned integer>
"max_entropylen" (OSSL_DRBG_PARAM_MAX_ENTROPYLEN) <unsigned integer>
Specify the minimum and maximum number of bytes of random material
that can be used to seed the DRBG.
"min_noncelen" (OSSL_DRBG_PARAM_MIN_NONCELEN) <unsigned integer>
"max_noncelen" (OSSL_DRBG_PARAM_MAX_NONCELEN) <unsigned integer>
Specify the minimum and maximum number of bytes of nonce that can be
used to instantiate the DRBG.
"max_perslen" (OSSL_DRBG_PARAM_MAX_PERSLEN) <unsigned integer>
"max_adinlen" (OSSL_DRBG_PARAM_MAX_ADINLEN) <unsigned integer>
Specify the minimum and maximum number of bytes of personalisation
string that can be used with the DRBG.
"reseed_counter" (OSSL_DRBG_PARAM_RESEED_COUNTER) <unsigned integer>
Specifies the number of times the DRBG has been seeded or reseeded.
"digest" (OSSL_DRBG_PARAM_DIGEST) <UTF8 string>
"cipher" (OSSL_DRBG_PARAM_CIPHER) <UTF8 string>
"mac" (OSSL_DRBG_PARAM_MAC) <UTF8 string>
Sets the name of the underlying cipher, digest or MAC to be used.
It must name a suitable algorithm for the DRBG that's being used.
"properties" (OSSL_DRBG_PARAM_PROPERTIES) <UTF8 string>
Sets the properties to be queried when trying to fetch an underlying
algorithm. This must be given together with the algorithm naming
parameter to be considered valid.
The OpenSSL FIPS provider also supports the following parameters:
"fips-indicator" (OSSL_DRBG_PARAM_FIPS_APPROVED_INDICATOR) <integer>
A getter that returns 1 if the operation is FIPS approved, or 0
otherwise. This may be used after calling
OSSL_FUNC_rand_generate(). It may return 0 if the "digest-check" is
set to 0.
"digest-check" (OSSL_DRBG_PARAM_FIPS_DIGEST_CHECK) <integer>
If required this parameter should be set before the digest is set.
The default value of 1 causes an error when the digest is set if the
digest is not FIPS approved (e.g. truncated digests). Setting this
to 0 will ignore the error and set the approved "fips-indicator" to
0. This option breaks FIPS compliance if it causes the approved
"fips-indicator" to return 0.
RETURN VALUES
OSSL_FUNC_rand_newctx() should return the newly created provider side
rand context, or NULL on failure.
OSSL_FUNC_rand_gettable_params(), OSSL_FUNC_rand_gettable_ctx_params()
and OSSL_FUNC_rand_settable_ctx_params() should return a constant
OSSL_PARAM(3) array, or NULL if none is offered.
OSSL_FUNC_rand_nonce() returns the size of the generated nonce, or 0 on
error.
OSSL_FUNC_rand_get_seed() returns the size of the generated seed, or 0
on error.
All of the remaining functions should return 1 for success or 0 on
error.
NOTES
The RAND life-cycle is described in life_cycle-rand(7). Providers
should ensure that the various transitions listed there are supported.
At some point the EVP layer will begin enforcing the listed transitions.
SEE ALSO
provider(7), RAND(7), EVP_RAND(7), life_cycle-rand(7), EVP_RAND(3)
HISTORY
The provider RAND interface was introduced in OpenSSL 3.0. The Rand
Parameters "fips-indicator" and "digest-check" were added in OpenSSL
3.4.
COPYRIGHT
Copyright 2020-2024 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
<https://www.openssl.org/source/license.html>.
3.5.4 2025-09-30 PROVIDER-RAND(7SSL)
Generated by dwww version 1.16 on Tue Dec 16 04:07:09 CET 2025.