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The RAND_DRBG API did not fit well into the new provider concept as implemented by EVP_RAND and EVP_RAND_CTX. The main reason is that the RAND_DRBG API is a mixture of 'front end' and 'back end' API calls and some of its API calls are rather low-level. This holds in particular for the callback mechanism (RAND_DRBG_set_callbacks()) and the RAND_DRBG type changing mechanism (RAND_DRBG_set()). Adding a compatibility layer to continue supporting the RAND_DRBG API as a legacy API for a regular deprecation period turned out to come at the price of complicating the new provider API unnecessarily. Since the RAND_DRBG API exists only since version 1.1.1, it was decided by the OMC to drop it entirely. Other related changes: Use RNG instead of DRBG in EVP_RAND documentation. The documentation was using DRBG in places where it should have been RNG or CSRNG. Move the RAND_DRBG(7) documentation to EVP_RAND(7). Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com> (Merged from https://github.com/openssl/openssl/pull/12509)
265 lines
9.7 KiB
Plaintext
265 lines
9.7 KiB
Plaintext
=pod
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=head1 NAME
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provider-rand - The random number generation library E<lt>-E<gt> provider
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functions
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=head1 SYNOPSIS
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=for openssl multiple includes
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#include <openssl/core_dispatch.h>
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#include <openssl/core_names.h>
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/*
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* None of these are actual functions, but are displayed like this for
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* the function signatures for functions that are offered as function
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* pointers in OSSL_DISPATCH arrays.
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*/
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/* Context management */
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void *OSSL_FUNC_rand_newctx(void *provctx, void *parent,
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const OSSL_DISPATCH *parent_calls);
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void OSSL_FUNC_rand_freectx(void *ctx);
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/* Random number generator functions: NIST */
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int OSSL_FUNC_rand_instantiate(void *ctx, unsigned int strength,
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int prediction_resistance,
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const unsigned char *pstr, size_t pstr_len);
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int OSSL_FUNC_rand_uninstantiate(void *ctx);
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int OSSL_FUNC_rand_generate(void *ctx, unsigned char *out, size_t outlen,
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unsigned int strength, int prediction_resistance,
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const unsigned char *addin, size_t addin_len);
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int OSSL_FUNC_rand_reseed(void *ctx, int prediction_resistance,
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const unsigned char *ent, size_t ent_len,
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const unsigned char *addin, size_t addin_len);
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/* Random number generator functions: additional */
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size_t OSSL_FUNC_rand_nonce(void *ctx, unsigned char *out, size_t outlen,
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int strength, size_t min_noncelen, size_t max_noncelen);
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int OSSL_FUNC_rand_verify_zeroization(void *ctx);
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/* Context Locking */
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int OSSL_FUNC_rand_enable_locking(void *ctx);
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int OSSL_FUNC_rand_lock(void *ctx);
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void OSSL_FUNC_rand_unlock(void *ctx);
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/* RAND parameter descriptors */
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const OSSL_PARAM *OSSL_FUNC_rand_gettable_params(void *provctx);
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const OSSL_PARAM *OSSL_FUNC_rand_gettable_ctx_params(void *provctx);
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const OSSL_PARAM *OSSL_FUNC_rand_settable_ctx_params(void *provctx);
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/* RAND parameters */
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int OSSL_FUNC_rand_get_params(OSSL_PARAM params[]);
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int OSSL_FUNC_rand_get_ctx_params(void *ctx, OSSL_PARAM params[]);
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int OSSL_FUNC_rand_set_ctx_params(void *ctx, const OSSL_PARAM params[]);
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=head1 DESCRIPTION
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This documentation is primarily aimed at provider authors. See L<provider(7)>
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for further information.
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The RAND operation enables providers to implement random number generation
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algorithms and random number sources and make
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them available to applications via the API function L<EVP_RAND(3)>.
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=head2 Context Management Functions
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OSSL_FUNC_rand_newctx() should create and return a pointer to a provider side
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structure for holding context information during a rand operation.
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A pointer to this context will be passed back in a number of the other rand
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operation function calls.
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The parameter I<provctx> is the provider context generated during provider
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initialisation (see L<provider(7)>).
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The parameter I<parent> specifies another rand instance to be used for
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seeding purposes. If NULL and the specific instance supports it, the
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operating system will be used for seeding.
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The parameter I<parent_calls> points to the dispatch table for I<parent>.
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Thus, the parent need not be from the same provider as the new instance.
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OSSL_FUNC_rand_freectx() is passed a pointer to the provider side rand context in
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the I<mctx> parameter.
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If it receives NULL as I<ctx> value, it should not do anything other than
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return.
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This function should free any resources associated with that context.
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=head2 Random Number Generator Functions: NIST
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These functions correspond to those defined in NIST SP 800-90A and SP 800-90C.
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OSSL_FUNC_rand_instantiate() is used to instantiate the DRBG I<ctx> at a requested
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security I<strength>. In addition, I<prediction_resistance> can be requested.
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Additional input I<addin> of length I<addin_len> bytes can optionally
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be provided.
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OSSL_FUNC_rand_uninstantiate() is used to uninstantiate the DRBG I<ctx>. After being
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uninstantiated, a DRBG is unable to produce output until it is instantiated
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anew.
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OSSL_FUNC_rand_generate() is used to generate random bytes from the DRBG I<ctx>.
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It will generate I<outlen> bytes placing them into the buffer pointed to by
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I<out>. The generated bytes will meet the specified security I<strength> and,
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if I<prediction_resistance> is true, the bytes will be produced after reseeding
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from a live entropy source. Additional input I<addin> of length I<addin_len>
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bytes can optionally be provided.
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=head2 Random Number Generator Functions: Additional
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OSSL_FUNC_rand_nonce() is used to generate a nonce of the given I<strength> with a
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length from I<min_noncelen> to I<max_noncelen>. If the output buffer I<out> is
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NULL, the length of the nonce should be returned.
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OSSL_FUNC_rand_verify_zeroization() is used to determine if the internal state of the
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DRBG is zero. This capability is mandated by NIST as part of the self
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tests, it is unlikely to be useful in other circumstances.
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=head2 Context Locking
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When DRBGs are used by multiple threads, there must be locking employed to
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ensure their proper operation. Because locking introduces an overhead, it
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is disabled by default.
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OSSL_FUNC_rand_enable_locking() allows locking to be turned on for a DRBG and all of
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its parent DRBGs. From this call onwards, the DRBG can be used in a thread
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safe manner.
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OSSL_FUNC_rand_lock() is used to lock a DRBG. Once locked, exclusive access
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is guaranteed.
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OSSL_FUNC_rand_unlock() is used to unlock a DRBG.
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=head2 Rand Parameters
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See L<OSSL_PARAM(3)> for further details on the parameters structure used by
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these functions.
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OSSL_FUNC_rand_get_params() gets details of parameter values associated with the
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provider algorithm and stores them in I<params>.
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OSSL_FUNC_rand_set_ctx_params() sets rand parameters associated with the given
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provider side rand context I<ctx> to I<params>.
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Any parameter settings are additional to any that were previously set.
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OSSL_FUNC_rand_get_ctx_params() gets details of currently set parameter values
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associated with the given provider side rand context I<ctx> and stores them
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in I<params>.
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OSSL_FUNC_rand_gettable_params(), OSSL_FUNC_rand_gettable_ctx_params(), and
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OSSL_FUNC_rand_settable_ctx_params() all return constant B<OSSL_PARAM> arrays
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as descriptors of the parameters that OSSL_FUNC_rand_get_params(),
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OSSL_FUNC_rand_get_ctx_params(), and OSSL_FUNC_rand_set_ctx_params() can handle,
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respectively.
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Parameters currently recognised by built-in rands are as follows. Not all
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parameters are relevant to, or are understood by all rands:
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=over 4
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=item "state" (B<OSSL_RAND_PARAM_STATE>) <integer>
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Returns the state of the random number generator.
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=item "strength" (B<OSSL_RAND_PARAM_STRENGTH>) <unsigned integer>
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Returns the bit strength of the random number generator.
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=back
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For rands that are also deterministic random bit generators (DRBGs), these
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additional parameters are recognised. Not all
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parameters are relevant to, or are understood by all DRBG rands:
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=over 4
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=item "reseed_requests" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer>
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Reads or set the number of generate requests before reseeding the
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associated RAND ctx.
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=item "reseed_time_interval" (B<OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL>) <integer>
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Reads or set the number of elapsed seconds before reseeding the
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associated RAND ctx.
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=item "max_request" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer>
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Specifies the maximum number of bytes that can be generated in a single
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call to OSSL_FUNC_rand_generate.
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=item "min_entropylen" (B<OSSL_DRBG_PARAM_MIN_ENTROPYLEN>) <unsigned integer>
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=item "max_entropylen" (B<OSSL_DRBG_PARAM_MAX_ENTROPYLEN>) <unsigned integer>
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Specify the minimum and maximum number of bytes of random material that
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can be used to seed the DRBG.
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=item "min_noncelen" (B<OSSL_DRBG_PARAM_MIN_NONCELEN>) <unsigned integer>
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=item "max_noncelen" (B<OSSL_DRBG_PARAM_MAX_NONCELEN>) <unsigned integer>
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Specify the minimum and maximum number of bytes of nonce that can be used to
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instantiate the DRBG.
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=item "max_perslen" (B<OSSL_DRBG_PARAM_MAX_PERSLEN>) <unsigned integer>
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=item "max_adinlen" (B<OSSL_DRBG_PARAM_MAX_ADINLEN>) <unsigned integer>
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Specify the minimum and maximum number of bytes of personalisation string
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that can be used with the DRBG.
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=item "reseed_counter" (B<OSSL_DRBG_PARAM_RESEED_CTR>) <unsigned integer>
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Specifies the number of times the DRBG has been seeded or reseeded.
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=item "digest" (B<OSSL_DRBG_PARAM_DIGEST>) <UTF8 string>
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=item "cipher" (B<OSSL_DRBG_PARAM_CIPHER>) <UTF8 string>
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=item "mac" (B<OSSL_DRBG_PARAM_MAC>) <UTF8 string>
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Sets the name of the underlying cipher, digest or MAC to be used.
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It must name a suitable algorithm for the DRBG that's being used.
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=item "properties" (B<OSSL_DRBG_PARAM_PROPERTIES>) <UTF8 string>
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Sets the properties to be queried when trying to fetch an underlying algorithm.
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This must be given together with the algorithm naming parameter to be
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considered valid.
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=back
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=head1 RETURN VALUES
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OSSL_FUNC_rand_newctx() should return the newly created
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provider side rand context, or NULL on failure.
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OSSL_FUNC_rand_gettable_params(), OSSL_FUNC_rand_gettable_ctx_params() and
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OSSL_FUNC_rand_settable_ctx_params() should return a constant B<OSSL_PARAM>
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array, or NULL if none is offered.
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OSSL_FUNC_rand_nonce() returns the size of the generated nonce, or 0 on error.
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All of the remaining functions should return 1 for success or 0 on error.
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=head1 SEE ALSO
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L<provider(7)>,
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L<RAND(7)>,
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L<EVP_RAND(7)>
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=head1 HISTORY
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The provider RAND interface was introduced in OpenSSL 3.0.
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=head1 COPYRIGHT
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Copyright 2020 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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