doc/man7/provider-kem.pod

   1 =pod
   2
   3 =head1 NAME
   4
   5 provider-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
  50 This documentation is primarily aimed at provider authors. See L<provider(7)>
  51 for further information.
  52
  53 The asymmetric kem (OSSL_OP_KEM) operation enables providers to
  54 implement asymmetric kem algorithms and make them available to applications
  55 via the API functions L<EVP_PKEY_encapsulate(3)>,
  56 L<EVP_PKEY_decapsulate(3)> and other related functions.
  57
  58 All "functions" mentioned here are passed as function pointers between
  59 F<libcrypto> and the provider in L<OSSL_DISPATCH(3)> arrays via
  60 L<OSSL_ALGORITHM(3)> arrays that are returned by the provider's
  61 provider_query_operation() function
  62 (see L<provider-base(7)/Provider Functions>).
  63
  64 All these "functions" have a corresponding function type definition
  65 named B<OSSL_FUNC_{name}_fn>, and a helper function to retrieve the
  66 function pointer from an L<OSSL_DISPATCH(3)> element named
  67 B<OSSL_FUNC_{name}>.
  68 For 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
  74 L<OSSL_DISPATCH(3)> arrays are indexed by numbers that are provided as
  75 macros 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
  94 An asymmetric kem algorithm implementation may not implement all of these
  95 functions.
  96 In order to be a consistent set of functions a provider must implement
  97 OSSL_FUNC_kem_newctx and OSSL_FUNC_kem_freectx.
  98 It must also implement both of OSSL_FUNC_kem_encapsulate_init and
  99 OSSL_FUNC_kem_encapsulate, or both of OSSL_FUNC_kem_decapsulate_init and
 100 OSSL_FUNC_kem_decapsulate.
 101 OSSL_FUNC_kem_auth_encapsulate_init is optional but if it is present then so
 102 must OSSL_FUNC_kem_auth_decapsulate_init.
 103 OSSL_FUNC_kem_get_ctx_params is optional but if it is present then so must
 104 OSSL_FUNC_kem_gettable_ctx_params.
 105 Similarly, OSSL_FUNC_kem_set_ctx_params is optional but if it is present then
 106 OSSL_FUNC_kem_settable_ctx_params must also be present.
 107
 108 An asymmetric kem algorithm must also implement some mechanism for generating,
 109 loading or importing keys via the key management (OSSL_OP_KEYMGMT) operation.
 110 See L<provider-keymgmt(7)> for further details.
 111
 112 =head2 Context Management Functions
 113
 114 OSSL_FUNC_kem_newctx() should create and return a pointer to a provider side
 115 structure for holding context information during an asymmetric kem operation.
 116 A pointer to this context will be passed back in a number of the other
 117 asymmetric kem operation function calls.
 118 The parameter I<provctx> is the provider context generated during provider
 119 initialisation (see L<provider(7)>).
 120
 121 OSSL_FUNC_kem_freectx() is passed a pointer to the provider side asymmetric
 122 kem context in the I<ctx> parameter.
 123 This function should free any resources associated with that context.
 124
 125 OSSL_FUNC_kem_dupctx() should duplicate the provider side asymmetric kem
 126 context in the I<ctx> parameter and return the duplicate copy.
 127
 128 =head2 Asymmetric Key Encapsulation Functions
 129
 130 OSSL_FUNC_kem_encapsulate_init() initialises a context for an asymmetric
 131 encapsulation given a provider side asymmetric kem context in the I<ctx>
 132 parameter, a pointer to a provider key object in the I<provkey> parameter and
 133 the I<name> of the algorithm.
 134 The I<params>, if not NULL, should be set on the context in a manner similar to
 135 using OSSL_FUNC_kem_set_ctx_params().
 136 The key object should have been previously generated, loaded or imported into
 137 the provider using the key management (OSSL_OP_KEYMGMT) operation (see
 138 provider-keymgmt(7)>.
 139
 140 OSSL_FUNC_kem_auth_encapsulate_init() is similiar to
 141 OSSL_FUNC_kem_encapsulate_init(), but also passes an additional authentication
 142 key I<provauthkey> which cannot be NULL.
 143
 144 OSSL_FUNC_kem_encapsulate() performs the actual encapsulation itself.
 145 A previously initialised asymmetric kem context is passed in the I<ctx>
 146 parameter.
 147 Unless I<out> is NULL, the data to be encapsulated is internally generated,
 148 and returned into the buffer pointed to by the I<secret> parameter and the
 149 encapsulated data should also be written to the location pointed to by the
 150 I<out> parameter. The length of the encapsulated data should be written to
 151 I<*outlen> and the length of the generated secret should be written to
 152 I<*secretlen>.
 153
 154 If I<out> is NULL then the maximum length of the encapsulated data should be
 155 written to I<*outlen>, and the maximum length of the generated secret should be
 156 written to I<*secretlen>.
 157
 158 =head2 Decapsulation Functions
 159
 160 OSSL_FUNC_kem_decapsulate_init() initialises a context for an asymmetric
 161 decapsulation given a provider side asymmetric kem context in the I<ctx>
 162 parameter, a pointer to a provider key object in the I<provkey> parameter, and
 163 a I<name> of the algorithm.
 164 The key object should have been previously generated, loaded or imported into
 165 the provider using the key management (OSSL_OP_KEYMGMT) operation (see
 166 provider-keymgmt(7)>.
 167
 168 OSSL_FUNC_kem_auth_decapsulate_init() is similiar to
 169 OSSL_FUNC_kem_decapsulate_init(), but also passes an additional authentication
 170 key I<provauthkey> which cannot be NULL.
 171
 172 OSSL_FUNC_kem_decapsulate() performs the actual decapsulation itself.
 173 A previously initialised asymmetric kem context is passed in the I<ctx>
 174 parameter.
 175 The data to be decapsulated is pointed to by the I<in> parameter which is I<inlen>
 176 bytes long.
 177 Unless I<out> is NULL, the decapsulated data should be written to the location
 178 pointed to by the I<out> parameter.
 179 The length of the decapsulated data should be written to I<*outlen>.
 180 If I<out> is NULL then the maximum length of the decapsulated data should be
 181 written to I<*outlen>.
 182
 183 =head2 Asymmetric Key Encapsulation Parameters
 184
 185 See L<OSSL_PARAM(3)> for further details on the parameters structure used by
 186 the OSSL_FUNC_kem_get_ctx_params() and OSSL_FUNC_kem_set_ctx_params()
 187 functions.
 188
 189 OSSL_FUNC_kem_get_ctx_params() gets asymmetric kem parameters associated
 190 with the given provider side asymmetric kem context I<ctx> and stores them in
 191 I<params>.
 192 Passing NULL for I<params> should return true.
 193
 194 OSSL_FUNC_kem_set_ctx_params() sets the asymmetric kem parameters associated
 195 with the given provider side asymmetric kem context I<ctx> to I<params>.
 196 Any parameter settings are additional to any that were previously set.
 197 Passing NULL for I<params> should return true.
 198
 199 No parameters are currently recognised by built-in asymmetric kem algorithms.
 200
 201 OSSL_FUNC_kem_gettable_ctx_params() and OSSL_FUNC_kem_settable_ctx_params()
 202 get a constant L<OSSL_PARAM(3)> array that describes the gettable and settable
 203 parameters, i.e. parameters that can be used with OSSL_FUNC_kem_get_ctx_params()
 204 and OSSL_FUNC_kem_set_ctx_params() respectively.
 205
 206 =head1 RETURN VALUES
 207
 208 OSSL_FUNC_kem_newctx() and OSSL_FUNC_kem_dupctx() should return the newly
 209 created provider side asymmetric kem context, or NULL on failure.
 210
 211 All other functions should return 1 for success or 0 on error.
 212
 213 =head1 SEE ALSO
 214
 215 L<provider(7)>
 216
 217 =head1 HISTORY
 218
 219 The provider KEM interface was introduced in OpenSSL 3.0.
 220
 221 OSSL_FUNC_kem_auth_encapsulate_init() and OSSL_FUNC_kem_auth_decapsulate_init()
 222 were added in OpenSSL 3.2.
 223
 224 =head1 COPYRIGHT
 225
 226 Copyright 2020-2022 The OpenSSL Project Authors. All Rights Reserved.
 227
 228 Licensed under the Apache License 2.0 (the "License").  You may not use
 229 this file except in compliance with the License.  You can obtain a copy
 230 in the file LICENSE in the source distribution or at
 231 L<https://www.openssl.org/source/license.html>.
 232
 233 =cut