provider-rand - The random number generation library <-> provider
functions
#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[]);
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).
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.
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.
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.
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.
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.
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.
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.
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.
provider(7),
RAND(7),
EVP_RAND(7),
life_cycle-rand(7),
EVP_RAND(3)
The provider RAND interface was introduced in OpenSSL 3.0.
Copyright 2020-2021 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>.