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261 lines
11 KiB
Plaintext
261 lines
11 KiB
Plaintext
=pod
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=head1 NAME
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provider-kem - The kem library E<lt>-E<gt> provider 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_kem_newctx(void *provctx);
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void OSSL_FUNC_kem_freectx(void *ctx);
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void *OSSL_FUNC_kem_dupctx(void *ctx);
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/* Encapsulation */
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int OSSL_FUNC_kem_encapsulate_init(void *ctx, void *provkey,
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const OSSL_PARAM params[]);
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int OSSL_FUNC_kem_auth_encapsulate_init(void *ctx, void *provkey,
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void *provauthkey,
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const OSSL_PARAM params[]);
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int OSSL_FUNC_kem_encapsulate(void *ctx, unsigned char *out, size_t *outlen,
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unsigned char *secret, size_t *secretlen);
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/* Decapsulation */
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int OSSL_FUNC_kem_decapsulate_init(void *ctx, void *provkey);
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int OSSL_FUNC_kem_auth_decapsulate_init(void *ctx, void *provkey,
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void *provauthkey,
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const OSSL_PARAM params[]);
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int OSSL_FUNC_kem_decapsulate(void *ctx, unsigned char *out, size_t *outlen,
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const unsigned char *in, size_t inlen);
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/* KEM parameters */
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int OSSL_FUNC_kem_get_ctx_params(void *ctx, OSSL_PARAM params[]);
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const OSSL_PARAM *OSSL_FUNC_kem_gettable_ctx_params(void *ctx, void *provctx);
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int OSSL_FUNC_kem_set_ctx_params(void *ctx, const OSSL_PARAM params[]);
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const OSSL_PARAM *OSSL_FUNC_kem_settable_ctx_params(void *ctx, void *provctx);
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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 asymmetric kem (OSSL_OP_KEM) operation enables providers to
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implement asymmetric kem algorithms and make them available to applications
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via the API functions L<EVP_PKEY_encapsulate(3)>,
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L<EVP_PKEY_decapsulate(3)> and other related functions.
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All "functions" mentioned here are passed as function pointers between
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F<libcrypto> and the provider in L<OSSL_DISPATCH(3)> arrays via
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L<OSSL_ALGORITHM(3)> arrays that are returned by the provider's
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provider_query_operation() function
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(see L<provider-base(7)/Provider Functions>).
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All these "functions" have a corresponding function type definition
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named B<OSSL_FUNC_{name}_fn>, and a helper function to retrieve the
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function pointer from an L<OSSL_DISPATCH(3)> element named
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B<OSSL_FUNC_{name}>.
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For example, the "function" OSSL_FUNC_kem_newctx() has these:
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typedef void *(OSSL_FUNC_kem_newctx_fn)(void *provctx);
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static ossl_inline OSSL_FUNC_kem_newctx_fn
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OSSL_FUNC_kem_newctx(const OSSL_DISPATCH *opf);
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L<OSSL_DISPATCH(3)> arrays are indexed by numbers that are provided as
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macros in L<openssl-core_dispatch.h(7)>, as follows:
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OSSL_FUNC_kem_newctx OSSL_FUNC_KEM_NEWCTX
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OSSL_FUNC_kem_freectx OSSL_FUNC_KEM_FREECTX
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OSSL_FUNC_kem_dupctx OSSL_FUNC_KEM_DUPCTX
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OSSL_FUNC_kem_encapsulate_init OSSL_FUNC_KEM_ENCAPSULATE_INIT
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OSSL_FUNC_kem_auth_encapsulate_init OSSL_FUNC_KEM_AUTH_ENCAPSULATE_INIT
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OSSL_FUNC_kem_encapsulate OSSL_FUNC_KEM_ENCAPSULATE
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OSSL_FUNC_kem_decapsulate_init OSSL_FUNC_KEM_DECAPSULATE_INIT
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OSSL_FUNC_kem_auth_decapsulate_init OSSL_FUNC_KEM_AUTH_DECAPSULATE_INIT
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OSSL_FUNC_kem_decapsulate OSSL_FUNC_KEM_DECAPSULATE
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OSSL_FUNC_kem_get_ctx_params OSSL_FUNC_KEM_GET_CTX_PARAMS
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OSSL_FUNC_kem_gettable_ctx_params OSSL_FUNC_KEM_GETTABLE_CTX_PARAMS
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OSSL_FUNC_kem_set_ctx_params OSSL_FUNC_KEM_SET_CTX_PARAMS
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OSSL_FUNC_kem_settable_ctx_params OSSL_FUNC_KEM_SETTABLE_CTX_PARAMS
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An asymmetric kem algorithm implementation may not implement all of these
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functions.
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In order to be a consistent set of functions a provider must implement
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OSSL_FUNC_kem_newctx and OSSL_FUNC_kem_freectx.
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It must also implement both of OSSL_FUNC_kem_encapsulate_init and
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OSSL_FUNC_kem_encapsulate, or both of OSSL_FUNC_kem_decapsulate_init and
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OSSL_FUNC_kem_decapsulate.
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OSSL_FUNC_kem_auth_encapsulate_init is optional but if it is present then so
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must OSSL_FUNC_kem_auth_decapsulate_init.
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OSSL_FUNC_kem_get_ctx_params is optional but if it is present then so must
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OSSL_FUNC_kem_gettable_ctx_params.
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Similarly, OSSL_FUNC_kem_set_ctx_params is optional but if it is present then
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OSSL_FUNC_kem_settable_ctx_params must also be present.
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An asymmetric kem algorithm must also implement some mechanism for generating,
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loading or importing keys via the key management (OSSL_OP_KEYMGMT) operation.
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See L<provider-keymgmt(7)> for further details.
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=head2 Context Management Functions
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OSSL_FUNC_kem_newctx() should create and return a pointer to a provider side
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structure for holding context information during an asymmetric kem operation.
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A pointer to this context will be passed back in a number of the other
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asymmetric kem 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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OSSL_FUNC_kem_freectx() is passed a pointer to the provider side asymmetric
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kem context in the I<ctx> parameter.
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This function should free any resources associated with that context.
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OSSL_FUNC_kem_dupctx() should duplicate the provider side asymmetric kem
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context in the I<ctx> parameter and return the duplicate copy.
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=head2 Asymmetric Key Encapsulation Functions
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OSSL_FUNC_kem_encapsulate_init() initialises a context for an asymmetric
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encapsulation given a provider side asymmetric kem context in the I<ctx>
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parameter, a pointer to a provider key object in the I<provkey> parameter and
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the I<name> of the algorithm.
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The I<params>, if not NULL, should be set on the context in a manner similar to
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using OSSL_FUNC_kem_set_ctx_params().
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The key object should have been previously generated, loaded or imported into
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the provider using the key management (OSSL_OP_KEYMGMT) operation (see
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provider-keymgmt(7)>.
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OSSL_FUNC_kem_auth_encapsulate_init() is similar to
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OSSL_FUNC_kem_encapsulate_init(), but also passes an additional authentication
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key I<provauthkey> which cannot be NULL.
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OSSL_FUNC_kem_encapsulate() performs the actual encapsulation itself.
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A previously initialised asymmetric kem context is passed in the I<ctx>
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parameter.
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Unless I<out> is NULL, the data to be encapsulated is internally generated,
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and returned into the buffer pointed to by the I<secret> parameter and the
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encapsulated data should also be written to the location pointed to by the
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I<out> parameter. The length of the encapsulated data should be written to
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I<*outlen> and the length of the generated secret should be written to
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I<*secretlen>.
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If I<out> is NULL then the maximum length of the encapsulated data should be
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written to I<*outlen>, and the maximum length of the generated secret should be
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written to I<*secretlen>.
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=head2 Decapsulation Functions
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OSSL_FUNC_kem_decapsulate_init() initialises a context for an asymmetric
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decapsulation given a provider side asymmetric kem context in the I<ctx>
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parameter, a pointer to a provider key object in the I<provkey> parameter, and
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a I<name> of the algorithm.
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The key object should have been previously generated, loaded or imported into
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the provider using the key management (OSSL_OP_KEYMGMT) operation (see
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provider-keymgmt(7)>.
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OSSL_FUNC_kem_auth_decapsulate_init() is similar to
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OSSL_FUNC_kem_decapsulate_init(), but also passes an additional authentication
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key I<provauthkey> which cannot be NULL.
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OSSL_FUNC_kem_decapsulate() performs the actual decapsulation itself.
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A previously initialised asymmetric kem context is passed in the I<ctx>
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parameter.
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The data to be decapsulated is pointed to by the I<in> parameter which is I<inlen>
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bytes long.
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Unless I<out> is NULL, the decapsulated data should be written to the location
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pointed to by the I<out> parameter.
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The length of the decapsulated data should be written to I<*outlen>.
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If I<out> is NULL then the maximum length of the decapsulated data should be
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written to I<*outlen>.
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=head2 Asymmetric Key Encapsulation Parameters
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See L<OSSL_PARAM(3)> for further details on the parameters structure used by
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the OSSL_FUNC_kem_get_ctx_params() and OSSL_FUNC_kem_set_ctx_params()
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functions.
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The OpenSSL FIPS provider also supports the following parameters:
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=over 4
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=item "fips-indicator" (B<OSSL_KEM_PARAM_FIPS_APPROVED_INDICATOR>) <integer>
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A getter that returns 1 if the operation is FIPS approved, or 0 otherwise.
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This may be used after calling either OSSL_FUNC_kem_encapsulate() or
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OSSL_FUNC_kem_decapsulate(). It may return 0 if the "key-check" is set to 0.
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=item "key-check" (B<OSSL_KEM_PARAM_FIPS_KEY_CHECK>) <integer>
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If required this parameter should be set using OSSL_FUNC_kem_encapsulate_init()
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or OSSL_FUNC_kem_decapsulate_init().
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The default value of 1 causes an error during the init if the key is not FIPS
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approved (e.g. The key has a security strength of less than 112 bits). Setting
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this to 0 will ignore the error and set the approved "fips-indicator" to 0.
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This option breaks FIPS compliance if it causes the approved "fips-indicator"
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to return 0.
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=back
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=head2 Asymmetric Key Encapsulation Parameter Functions
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OSSL_FUNC_kem_get_ctx_params() gets asymmetric KEM parameters associated
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with the given provider side asymmetric kem context I<ctx> and stores them in
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I<params>.
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Passing NULL for I<params> should return true.
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OSSL_FUNC_kem_set_ctx_params() sets the asymmetric KEM parameters associated
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with the given provider side asymmetric kem 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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Passing NULL for I<params> should return true.
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No parameters are currently recognised by built-in asymmetric kem algorithms.
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OSSL_FUNC_kem_gettable_ctx_params() and OSSL_FUNC_kem_settable_ctx_params()
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get a constant L<OSSL_PARAM(3)> array that describes the gettable and settable
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parameters, i.e. parameters that can be used with OSSL_FUNC_kem_get_ctx_params()
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and OSSL_FUNC_kem_set_ctx_params() respectively.
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=head1 RETURN VALUES
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OSSL_FUNC_kem_newctx() and OSSL_FUNC_kem_dupctx() should return the newly
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created provider side asymmetric kem context, or NULL on failure.
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All other 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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=head1 HISTORY
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The provider KEM interface was introduced in OpenSSL 3.0.
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OSSL_FUNC_kem_auth_encapsulate_init() and OSSL_FUNC_kem_auth_decapsulate_init()
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were added in OpenSSL 3.2.
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The Asymmetric Key Encapsulation Parameters "fips-indicator" and "key-check"
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were added in OpenSSL 3.4.
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=head1 COPYRIGHT
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Copyright 2020-2024 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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