doc/man7/provider-asym_cipher.pod

   1 =pod
   2
   3 =head1 NAME
   4
   5 provider-asym_cipher - The asym_cipher 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_asym_cipher_newctx(void *provctx);
  22  void OSSL_FUNC_asym_cipher_freectx(void *ctx);
  23  void *OSSL_FUNC_asym_cipher_dupctx(void *ctx);
  24
  25  /* Encryption */
  26  int OSSL_FUNC_asym_cipher_encrypt_init(void *ctx, void *provkey,
  27                                         const OSSL_PARAM params[]);
  28  int OSSL_FUNC_asym_cipher_encrypt(void *ctx, unsigned char *out, size_t *outlen,
  29                                    size_t outsize, const unsigned char *in,
  30                                    size_t inlen);
  31
  32  /* Decryption */
  33  int OSSL_FUNC_asym_cipher_decrypt_init(void *ctx, void *provkey,
  34                                         const OSSL_PARAM params[]);
  35  int OSSL_FUNC_asym_cipher_decrypt(void *ctx, unsigned char *out, size_t *outlen,
  36                                    size_t outsize, const unsigned char *in,
  37                                    size_t inlen);
  38
  39  /* Asymmetric Cipher parameters */
  40  int OSSL_FUNC_asym_cipher_get_ctx_params(void *ctx, OSSL_PARAM params[]);
  41  const OSSL_PARAM *OSSL_FUNC_asym_cipher_gettable_ctx_params(void *provctx);
  42  int OSSL_FUNC_asym_cipher_set_ctx_params(void *ctx, const OSSL_PARAM params[]);
  43  const OSSL_PARAM *OSSL_FUNC_asym_cipher_settable_ctx_params(void *provctx);
  44
  45 =head1 DESCRIPTION
  46
  47 This documentation is primarily aimed at provider authors. See L<provider(7)>
  48 for further information.
  49
  50 The asymmetric cipher (OSSL_OP_ASYM_CIPHER) operation enables providers to
  51 implement asymmetric cipher algorithms and make them available to applications
  52 via the API functions L<EVP_PKEY_encrypt(3)>,
  53 L<EVP_PKEY_decrypt(3)> and
  54 other related functions).
  55
  56 All "functions" mentioned here are passed as function pointers between
  57 F<libcrypto> and the provider in L<OSSL_DISPATCH(3)> arrays via
  58 L<OSSL_ALGORITHM(3)> arrays that are returned by the provider's
  59 provider_query_operation() function
  60 (see L<provider-base(7)/Provider Functions>).
  61
  62 All these "functions" have a corresponding function type definition
  63 named B<OSSL_FUNC_{name}_fn>, and a helper function to retrieve the
  64 function pointer from an L<OSSL_DISPATCH(3)> element named
  65 B<OSSL_FUNC_{name}>.
  66 For example, the "function" OSSL_FUNC_asym_cipher_newctx() has these:
  67
  68  typedef void *(OSSL_FUNC_asym_cipher_newctx_fn)(void *provctx);
  69  static ossl_inline OSSL_FUNC_asym_cipher_newctx_fn
  70      OSSL_FUNC_asym_cipher_newctx(const OSSL_DISPATCH *opf);
  71
  72 L<OSSL_DISPATCH(3)> arrays are indexed by numbers that are provided as
  73 macros in L<openssl-core_dispatch.h(7)>, as follows:
  74
  75  OSSL_FUNC_asym_cipher_newctx               OSSL_FUNC_ASYM_CIPHER_NEWCTX
  76  OSSL_FUNC_asym_cipher_freectx              OSSL_FUNC_ASYM_CIPHER_FREECTX
  77  OSSL_FUNC_asym_cipher_dupctx               OSSL_FUNC_ASYM_CIPHER_DUPCTX
  78
  79  OSSL_FUNC_asym_cipher_encrypt_init         OSSL_FUNC_ASYM_CIPHER_ENCRYPT_INIT
  80  OSSL_FUNC_asym_cipher_encrypt              OSSL_FUNC_ASYM_CIPHER_ENCRYPT
  81
  82  OSSL_FUNC_asym_cipher_decrypt_init         OSSL_FUNC_ASYM_CIPHER_DECRYPT_INIT
  83  OSSL_FUNC_asym_cipher_decrypt              OSSL_FUNC_ASYM_CIPHER_DECRYPT
  84
  85  OSSL_FUNC_asym_cipher_get_ctx_params       OSSL_FUNC_ASYM_CIPHER_GET_CTX_PARAMS
  86  OSSL_FUNC_asym_cipher_gettable_ctx_params  OSSL_FUNC_ASYM_CIPHER_GETTABLE_CTX_PARAMS
  87  OSSL_FUNC_asym_cipher_set_ctx_params       OSSL_FUNC_ASYM_CIPHER_SET_CTX_PARAMS
  88  OSSL_FUNC_asym_cipher_settable_ctx_params  OSSL_FUNC_ASYM_CIPHER_SETTABLE_CTX_PARAMS
  89
  90 An asymmetric cipher algorithm implementation may not implement all of these
  91 functions.
  92 In order to be a consistent set of functions a provider must implement
  93 OSSL_FUNC_asym_cipher_newctx and OSSL_FUNC_asym_cipher_freectx.
  94 It must also implement both of OSSL_FUNC_asym_cipher_encrypt_init and
  95 OSSL_FUNC_asym_cipher_encrypt, or both of OSSL_FUNC_asym_cipher_decrypt_init and
  96 OSSL_FUNC_asym_cipher_decrypt.
  97 OSSL_FUNC_asym_cipher_get_ctx_params is optional but if it is present then so must
  98 OSSL_FUNC_asym_cipher_gettable_ctx_params.
  99 Similarly, OSSL_FUNC_asym_cipher_set_ctx_params is optional but if it is present then
 100 so must OSSL_FUNC_asym_cipher_settable_ctx_params.
 101
 102 An asymmetric cipher algorithm must also implement some mechanism for generating,
 103 loading or importing keys via the key management (OSSL_OP_KEYMGMT) operation.
 104 See L<provider-keymgmt(7)> for further details.
 105
 106 =head2 Context Management Functions
 107
 108 OSSL_FUNC_asym_cipher_newctx() should create and return a pointer to a provider side
 109 structure for holding context information during an asymmetric cipher operation.
 110 A pointer to this context will be passed back in a number of the other
 111 asymmetric cipher operation function calls.
 112 The parameter I<provctx> is the provider context generated during provider
 113 initialisation (see L<provider(7)>).
 114
 115 OSSL_FUNC_asym_cipher_freectx() is passed a pointer to the provider side asymmetric
 116 cipher context in the I<ctx> parameter.
 117 This function should free any resources associated with that context.
 118
 119 OSSL_FUNC_asym_cipher_dupctx() should duplicate the provider side asymmetric cipher
 120 context in the I<ctx> parameter and return the duplicate copy.
 121
 122 =head2 Encryption Functions
 123
 124 OSSL_FUNC_asym_cipher_encrypt_init() initialises a context for an asymmetric encryption
 125 given a provider side asymmetric cipher context in the I<ctx> parameter, and a
 126 pointer to a provider key object in the I<provkey> parameter.
 127 The I<params>, if not NULL, should be set on the context in a manner similar to
 128 using OSSL_FUNC_asym_cipher_set_ctx_params().
 129 The key object should have been previously generated, loaded or imported into
 130 the provider using the key management (OSSL_OP_KEYMGMT) operation (see L<provider-keymgmt(7)>).
 131 OSSL_FUNC_asym_cipher_encrypt() performs the actual encryption itself.
 132 A previously initialised asymmetric cipher context is passed in the I<ctx>
 133 parameter.
 134 The data to be encrypted is pointed to by the I<in> parameter which is I<inlen>
 135 bytes long.
 136 Unless I<out> is NULL, the encrypted data should be written to the location
 137 pointed to by the I<out> parameter and it should not exceed I<outsize> bytes in
 138 length.
 139 The length of the encrypted data should be written to I<*outlen>.
 140 If I<out> is NULL then the maximum length of the encrypted data should be
 141 written to I<*outlen>.
 142
 143 =head2 Decryption Functions
 144
 145 OSSL_FUNC_asym_cipher_decrypt_init() initialises a context for an asymmetric decryption
 146 given a provider side asymmetric cipher context in the I<ctx> parameter, and a
 147 pointer to a provider key object in the I<provkey> parameter.
 148 The I<params>, if not NULL, should be set on the context in a manner similar to
 149 using OSSL_FUNC_asym_cipher_set_ctx_params().
 150 The key object should have been previously generated, loaded or imported into
 151 the provider using the key management (OSSL_OP_KEYMGMT) operation (see
 152 L<provider-keymgmt(7)>).
 153
 154 OSSL_FUNC_asym_cipher_decrypt() performs the actual decryption itself.
 155 A previously initialised asymmetric cipher context is passed in the I<ctx>
 156 parameter.
 157 The data to be decrypted is pointed to by the I<in> parameter which is I<inlen>
 158 bytes long.
 159 Unless I<out> is NULL, the decrypted data should be written to the location
 160 pointed to by the I<out> parameter and it should not exceed I<outsize> bytes in
 161 length.
 162 The length of the decrypted data should be written to I<*outlen>.
 163 If I<out> is NULL then the maximum length of the decrypted data should be
 164 written to I<*outlen>.
 165
 166 =head2 Asymmetric Cipher Parameters
 167
 168 See L<OSSL_PARAM(3)> for further details on the parameters structure used by
 169 the OSSL_FUNC_asym_cipher_get_ctx_params() and OSSL_FUNC_asym_cipher_set_ctx_params()
 170 functions.
 171
 172 OSSL_FUNC_asym_cipher_get_ctx_params() gets asymmetric cipher parameters associated
 173 with the given provider side asymmetric cipher context I<ctx> and stores them in
 174 I<params>.
 175 Passing NULL for I<params> should return true.
 176
 177 OSSL_FUNC_asym_cipher_set_ctx_params() sets the asymmetric cipher parameters associated
 178 with the given provider side asymmetric cipher context I<ctx> to I<params>.
 179 Any parameter settings are additional to any that were previously set.
 180 Passing NULL for I<params> should return true.
 181
 182 Parameters currently recognised by built-in asymmetric cipher algorithms are as
 183 follows.
 184 Not all parameters are relevant to, or are understood by all asymmetric cipher
 185 algorithms:
 186
 187 =over 4
 188
 189 =item "pad-mode" (B<OSSL_ASYM_CIPHER_PARAM_PAD_MODE>) <UTF8 string> OR <integer>
 190
 191 The type of padding to be used. The interpretation of this value will depend
 192 on the algorithm in use.
 193
 194 =item "digest" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST>) <UTF8 string>
 195
 196 Gets or sets the name of the OAEP digest algorithm used when OAEP padding is in
 197 use.
 198
 199 =item "digest" (B<OSSL_ASYM_CIPHER_PARAM_DIGEST>) <UTF8 string>
 200
 201 Gets or sets the name of the digest algorithm used by the algorithm (where
 202 applicable).
 203
 204 =item "digest-props" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_DIGEST_PROPS>) <UTF8 string>
 205
 206 Gets or sets the properties to use when fetching the OAEP digest algorithm.
 207
 208 =item "digest-props" (B<OSSL_ASYM_CIPHER_PARAM_DIGEST_PROPS>) <UTF8 string>
 209
 210 Gets or sets the properties to use when fetching the cipher digest algorithm.
 211
 212 =item "mgf1-digest" (B<OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST>) <UTF8 string>
 213
 214 Gets or sets the name of the MGF1 digest algorithm used when OAEP or PSS padding
 215 is in use.
 216
 217 =item "mgf1-digest-props" (B<OSSL_ASYM_CIPHER_PARAM_MGF1_DIGEST_PROPS>) <UTF8 string>
 218
 219 Gets or sets the properties to use when fetching the MGF1 digest algorithm.
 220
 221 =item "oaep-label" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_LABEL>) <octet string ptr>
 222
 223 Gets the OAEP label used when OAEP padding is in use.
 224
 225 =item "oaep-label" (B<OSSL_ASYM_CIPHER_PARAM_OAEP_LABEL>) <octet string>
 226
 227 Sets the OAEP label used when OAEP padding is in use.
 228
 229 =item "tls-client-version" (B<OSSL_ASYM_CIPHER_PARAM_TLS_CLIENT_VERSION>) <unsigned integer>
 230
 231 The TLS protocol version first requested by the client.
 232
 233 =item "tls-negotiated-version" (B<OSSL_ASYM_CIPHER_PARAM_TLS_CLIENT_VERSION>) <unsigned integer>
 234
 235 The negotiated TLS protocol version.
 236
 237 =item "implicit-rejection" (B<OSSL_PKEY_PARAM_IMPLICIT_REJECTION>) <unsigned integer>
 238
 239 Gets of sets the use of the implicit rejection mechanism for RSA PKCS#1 v1.5
 240 decryption. When set (non zero value), the decryption API will return
 241 a deterministically random value if the PKCS#1 v1.5 padding check fails.
 242 This makes exploitation of the Bleichenbacher significantly harder, even
 243 if the code using the RSA decryption API is not implemented in side-channel
 244 free manner. Set by default.
 245
 246 =back
 247
 248 OSSL_FUNC_asym_cipher_gettable_ctx_params() and OSSL_FUNC_asym_cipher_settable_ctx_params()
 249 get a constant L<OSSL_PARAM(3)> array that describes the gettable and settable
 250 parameters, i.e. parameters that can be used with OSSL_FUNC_asym_cipherget_ctx_params()
 251 and OSSL_FUNC_asym_cipher_set_ctx_params() respectively.
 252
 253 =head1 RETURN VALUES
 254
 255 OSSL_FUNC_asym_cipher_newctx() and OSSL_FUNC_asym_cipher_dupctx() should return the newly
 256 created provider side asymmetric cipher context, or NULL on failure.
 257
 258 All other functions should return 1 for success or 0 on error.
 259
 260 =head1 SEE ALSO
 261
 262 L<provider(7)>
 263
 264 =head1 HISTORY
 265
 266 The provider ASYM_CIPHER interface was introduced in OpenSSL 3.0.
 267
 268 =head1 COPYRIGHT
 269
 270 Copyright 2019-2023 The OpenSSL Project Authors. All Rights Reserved.
 271
 272 Licensed under the Apache License 2.0 (the "License").  You may not use
 273 this file except in compliance with the License.  You can obtain a copy
 274 in the file LICENSE in the source distribution or at
 275 L<https://www.openssl.org/source/license.html>.
 276
 277 =cut