1=pod 2 3=head1 NAME 4 5provider-kem - The kem library E<lt>-E<gt> provider functions 6 7=head1 SYNOPSIS 8 9=for openssl multiple includes 10 11 #include <openssl/core_dispatch.h> 12 #include <openssl/core_names.h> 13 14 /* 15 * None of these are actual functions, but are displayed like this for 16 * the function signatures for functions that are offered as function 17 * pointers in OSSL_DISPATCH arrays. 18 */ 19 20 /* Context management */ 21 void *OSSL_FUNC_kem_newctx(void *provctx); 22 void OSSL_FUNC_kem_freectx(void *ctx); 23 void *OSSL_FUNC_kem_dupctx(void *ctx); 24 25 /* Encapsulation */ 26 int OSSL_FUNC_kem_encapsulate_init(void *ctx, void *provkey, 27 const OSSL_PARAM params[]); 28 int OSSL_FUNC_kem_auth_encapsulate_init(void *ctx, void *provkey, 29 void *provauthkey, 30 const OSSL_PARAM params[]); 31 int OSSL_FUNC_kem_encapsulate(void *ctx, unsigned char *out, size_t *outlen, 32 unsigned char *secret, size_t *secretlen); 33 34 /* Decapsulation */ 35 int OSSL_FUNC_kem_decapsulate_init(void *ctx, void *provkey); 36 int OSSL_FUNC_kem_auth_decapsulate_init(void *ctx, void *provkey, 37 void *provauthkey, 38 const OSSL_PARAM params[]); 39 int OSSL_FUNC_kem_decapsulate(void *ctx, unsigned char *out, size_t *outlen, 40 const unsigned char *in, size_t inlen); 41 42 /* KEM parameters */ 43 int OSSL_FUNC_kem_get_ctx_params(void *ctx, OSSL_PARAM params[]); 44 const OSSL_PARAM *OSSL_FUNC_kem_gettable_ctx_params(void *ctx, void *provctx); 45 int OSSL_FUNC_kem_set_ctx_params(void *ctx, const OSSL_PARAM params[]); 46 const OSSL_PARAM *OSSL_FUNC_kem_settable_ctx_params(void *ctx, void *provctx); 47 48=head1 DESCRIPTION 49 50This documentation is primarily aimed at provider authors. See L<provider(7)> 51for further information. 52 53The asymmetric kem (OSSL_OP_KEM) operation enables providers to 54implement asymmetric kem algorithms and make them available to applications 55via the API functions L<EVP_PKEY_encapsulate(3)>, 56L<EVP_PKEY_decapsulate(3)> and other related functions. 57 58All "functions" mentioned here are passed as function pointers between 59F<libcrypto> and the provider in L<OSSL_DISPATCH(3)> arrays via 60L<OSSL_ALGORITHM(3)> arrays that are returned by the provider's 61provider_query_operation() function 62(see L<provider-base(7)/Provider Functions>). 63 64All these "functions" have a corresponding function type definition 65named B<OSSL_FUNC_{name}_fn>, and a helper function to retrieve the 66function pointer from an L<OSSL_DISPATCH(3)> element named 67B<OSSL_FUNC_{name}>. 68For example, the "function" OSSL_FUNC_kem_newctx() has these: 69 70 typedef void *(OSSL_FUNC_kem_newctx_fn)(void *provctx); 71 static ossl_inline OSSL_FUNC_kem_newctx_fn 72 OSSL_FUNC_kem_newctx(const OSSL_DISPATCH *opf); 73 74L<OSSL_DISPATCH(3)> arrays are indexed by numbers that are provided as 75macros in L<openssl-core_dispatch.h(7)>, as follows: 76 77 OSSL_FUNC_kem_newctx OSSL_FUNC_KEM_NEWCTX 78 OSSL_FUNC_kem_freectx OSSL_FUNC_KEM_FREECTX 79 OSSL_FUNC_kem_dupctx OSSL_FUNC_KEM_DUPCTX 80 81 OSSL_FUNC_kem_encapsulate_init OSSL_FUNC_KEM_ENCAPSULATE_INIT 82 OSSL_FUNC_kem_auth_encapsulate_init OSSL_FUNC_KEM_AUTH_ENCAPSULATE_INIT 83 OSSL_FUNC_kem_encapsulate OSSL_FUNC_KEM_ENCAPSULATE 84 85 OSSL_FUNC_kem_decapsulate_init OSSL_FUNC_KEM_DECAPSULATE_INIT 86 OSSL_FUNC_kem_auth_decapsulate_init OSSL_FUNC_KEM_AUTH_DECAPSULATE_INIT 87 OSSL_FUNC_kem_decapsulate OSSL_FUNC_KEM_DECAPSULATE 88 89 OSSL_FUNC_kem_get_ctx_params OSSL_FUNC_KEM_GET_CTX_PARAMS 90 OSSL_FUNC_kem_gettable_ctx_params OSSL_FUNC_KEM_GETTABLE_CTX_PARAMS 91 OSSL_FUNC_kem_set_ctx_params OSSL_FUNC_KEM_SET_CTX_PARAMS 92 OSSL_FUNC_kem_settable_ctx_params OSSL_FUNC_KEM_SETTABLE_CTX_PARAMS 93 94An asymmetric kem algorithm implementation may not implement all of these 95functions. 96In order to be a consistent set of functions a provider must implement 97OSSL_FUNC_kem_newctx and OSSL_FUNC_kem_freectx. 98It must also implement both of OSSL_FUNC_kem_encapsulate_init and 99OSSL_FUNC_kem_encapsulate, or both of OSSL_FUNC_kem_decapsulate_init and 100OSSL_FUNC_kem_decapsulate. 101OSSL_FUNC_kem_auth_encapsulate_init is optional but if it is present then so 102must OSSL_FUNC_kem_auth_decapsulate_init. 103OSSL_FUNC_kem_get_ctx_params is optional but if it is present then so must 104OSSL_FUNC_kem_gettable_ctx_params. 105Similarly, OSSL_FUNC_kem_set_ctx_params is optional but if it is present then 106OSSL_FUNC_kem_settable_ctx_params must also be present. 107 108An asymmetric kem algorithm must also implement some mechanism for generating, 109loading or importing keys via the key management (OSSL_OP_KEYMGMT) operation. 110See L<provider-keymgmt(7)> for further details. 111 112=head2 Context Management Functions 113 114OSSL_FUNC_kem_newctx() should create and return a pointer to a provider side 115structure for holding context information during an asymmetric kem operation. 116A pointer to this context will be passed back in a number of the other 117asymmetric kem operation function calls. 118The parameter I<provctx> is the provider context generated during provider 119initialisation (see L<provider(7)>). 120 121OSSL_FUNC_kem_freectx() is passed a pointer to the provider side asymmetric 122kem context in the I<ctx> parameter. 123This function should free any resources associated with that context. 124 125OSSL_FUNC_kem_dupctx() should duplicate the provider side asymmetric kem 126context in the I<ctx> parameter and return the duplicate copy. 127 128=head2 Asymmetric Key Encapsulation Functions 129 130OSSL_FUNC_kem_encapsulate_init() initialises a context for an asymmetric 131encapsulation given a provider side asymmetric kem context in the I<ctx> 132parameter, a pointer to a provider key object in the I<provkey> parameter and 133the I<name> of the algorithm. 134The I<params>, if not NULL, should be set on the context in a manner similar to 135using OSSL_FUNC_kem_set_ctx_params(). 136The key object should have been previously generated, loaded or imported into 137the provider using the key management (OSSL_OP_KEYMGMT) operation (see 138provider-keymgmt(7)>. 139 140OSSL_FUNC_kem_auth_encapsulate_init() is similar to 141OSSL_FUNC_kem_encapsulate_init(), but also passes an additional authentication 142key I<provauthkey> which cannot be NULL. 143 144OSSL_FUNC_kem_encapsulate() performs the actual encapsulation itself. 145A previously initialised asymmetric kem context is passed in the I<ctx> 146parameter. 147Unless I<out> is NULL, the data to be encapsulated is internally generated, 148and returned into the buffer pointed to by the I<secret> parameter and the 149encapsulated data should also be written to the location pointed to by the 150I<out> parameter. The length of the encapsulated data should be written to 151I<*outlen> and the length of the generated secret should be written to 152I<*secretlen>. 153 154If I<out> is NULL then the maximum length of the encapsulated data should be 155written to I<*outlen>, and the maximum length of the generated secret should be 156written to I<*secretlen>. 157 158=head2 Decapsulation Functions 159 160OSSL_FUNC_kem_decapsulate_init() initialises a context for an asymmetric 161decapsulation given a provider side asymmetric kem context in the I<ctx> 162parameter, a pointer to a provider key object in the I<provkey> parameter, and 163a I<name> of the algorithm. 164The key object should have been previously generated, loaded or imported into 165the provider using the key management (OSSL_OP_KEYMGMT) operation (see 166provider-keymgmt(7)>. 167 168OSSL_FUNC_kem_auth_decapsulate_init() is similar to 169OSSL_FUNC_kem_decapsulate_init(), but also passes an additional authentication 170key I<provauthkey> which cannot be NULL. 171 172OSSL_FUNC_kem_decapsulate() performs the actual decapsulation itself. 173A previously initialised asymmetric kem context is passed in the I<ctx> 174parameter. 175The data to be decapsulated is pointed to by the I<in> parameter which is I<inlen> 176bytes long. 177Unless I<out> is NULL, the decapsulated data should be written to the location 178pointed to by the I<out> parameter. 179The length of the decapsulated data should be written to I<*outlen>. 180If I<out> is NULL then the maximum length of the decapsulated data should be 181written to I<*outlen>. 182 183=head2 Asymmetric Key Encapsulation Parameters 184 185See L<OSSL_PARAM(3)> for further details on the parameters structure used by 186the OSSL_FUNC_kem_get_ctx_params() and OSSL_FUNC_kem_set_ctx_params() 187functions. 188 189The OpenSSL FIPS provider also supports the following parameters: 190 191=over 4 192 193=item "fips-indicator" (B<OSSL_KEM_PARAM_FIPS_APPROVED_INDICATOR>) <integer> 194 195A getter that returns 1 if the operation is FIPS approved, or 0 otherwise. 196This may be used after calling either OSSL_FUNC_kem_encapsulate() or 197OSSL_FUNC_kem_decapsulate(). It may return 0 if the "key-check" is set to 0. 198 199=item "key-check" (B<OSSL_KEM_PARAM_FIPS_KEY_CHECK>) <integer> 200 201If required this parameter should be set using OSSL_FUNC_kem_encapsulate_init() 202or OSSL_FUNC_kem_decapsulate_init(). 203The default value of 1 causes an error during the init if the key is not FIPS 204approved (e.g. The key has a security strength of less than 112 bits). Setting 205this to 0 will ignore the error and set the approved "fips-indicator" to 0. 206This option breaks FIPS compliance if it causes the approved "fips-indicator" 207to return 0. 208 209=back 210 211=head2 Asymmetric Key Encapsulation Parameter Functions 212 213OSSL_FUNC_kem_get_ctx_params() gets asymmetric KEM parameters associated 214with the given provider side asymmetric kem context I<ctx> and stores them in 215I<params>. 216Passing NULL for I<params> should return true. 217 218OSSL_FUNC_kem_set_ctx_params() sets the asymmetric KEM parameters associated 219with the given provider side asymmetric kem context I<ctx> to I<params>. 220Any parameter settings are additional to any that were previously set. 221Passing NULL for I<params> should return true. 222 223No parameters are currently recognised by built-in asymmetric kem algorithms. 224 225OSSL_FUNC_kem_gettable_ctx_params() and OSSL_FUNC_kem_settable_ctx_params() 226get a constant L<OSSL_PARAM(3)> array that describes the gettable and settable 227parameters, i.e. parameters that can be used with OSSL_FUNC_kem_get_ctx_params() 228and OSSL_FUNC_kem_set_ctx_params() respectively. 229 230=head1 RETURN VALUES 231 232OSSL_FUNC_kem_newctx() and OSSL_FUNC_kem_dupctx() should return the newly 233created provider side asymmetric kem context, or NULL on failure. 234 235All other functions should return 1 for success or 0 on error. 236 237=head1 SEE ALSO 238 239L<provider(7)> 240 241=head1 HISTORY 242 243The provider KEM interface was introduced in OpenSSL 3.0. 244 245OSSL_FUNC_kem_auth_encapsulate_init() and OSSL_FUNC_kem_auth_decapsulate_init() 246were added in OpenSSL 3.2. 247 248The Asymmetric Key Encapsulation Parameters "fips-indicator" and "key-check" 249were added in OpenSSL 3.4. 250 251=head1 COPYRIGHT 252 253Copyright 2020-2024 The OpenSSL Project Authors. All Rights Reserved. 254 255Licensed under the Apache License 2.0 (the "License"). You may not use 256this file except in compliance with the License. You can obtain a copy 257in the file LICENSE in the source distribution or at 258L<https://www.openssl.org/source/license.html>. 259 260=cut 261
