1=pod 2 3=head1 NAME 4 5provider-kdf - The KDF 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_kdf_newctx(void *provctx); 22 void OSSL_FUNC_kdf_freectx(void *kctx); 23 void *OSSL_FUNC_kdf_dupctx(void *src); 24 25 /* Encryption/decryption */ 26 int OSSL_FUNC_kdf_reset(void *kctx); 27 int OSSL_FUNC_kdf_derive(void *kctx, unsigned char *key, size_t keylen, 28 const OSSL_PARAM params[]); 29 30 /* KDF parameter descriptors */ 31 const OSSL_PARAM *OSSL_FUNC_kdf_gettable_params(void *provctx); 32 const OSSL_PARAM *OSSL_FUNC_kdf_gettable_ctx_params(void *kcxt, void *provctx); 33 const OSSL_PARAM *OSSL_FUNC_kdf_settable_ctx_params(void *kcxt, void *provctx); 34 35 /* KDF parameters */ 36 int OSSL_FUNC_kdf_get_params(OSSL_PARAM params[]); 37 int OSSL_FUNC_kdf_get_ctx_params(void *kctx, OSSL_PARAM params[]); 38 int OSSL_FUNC_kdf_set_ctx_params(void *kctx, const OSSL_PARAM params[]); 39 40=head1 DESCRIPTION 41 42This documentation is primarily aimed at provider authors. See L<provider(7)> 43for further information. 44 45The KDF operation enables providers to implement KDF algorithms and make 46them available to applications via the API functions L<EVP_KDF_CTX_reset(3)>, 47and L<EVP_KDF_derive(3)>. 48 49All "functions" mentioned here are passed as function pointers between 50F<libcrypto> and the provider in L<OSSL_DISPATCH(3)> arrays via 51L<OSSL_ALGORITHM(3)> arrays that are returned by the provider's 52provider_query_operation() function 53(see L<provider-base(7)/Provider Functions>). 54 55All these "functions" have a corresponding function type definition 56named B<OSSL_FUNC_{name}_fn>, and a helper function to retrieve the 57function pointer from an L<OSSL_DISPATCH(3)> element named 58B<OSSL_FUNC_{name}>. 59For example, the "function" OSSL_FUNC_kdf_newctx() has these: 60 61 typedef void *(OSSL_FUNC_kdf_newctx_fn)(void *provctx); 62 static ossl_inline OSSL_FUNC_kdf_newctx_fn 63 OSSL_FUNC_kdf_newctx(const OSSL_DISPATCH *opf); 64 65L<OSSL_DISPATCH(3)> array entries are identified by numbers that are provided as 66macros in L<openssl-core_dispatch.h(7)>, as follows: 67 68 OSSL_FUNC_kdf_newctx OSSL_FUNC_KDF_NEWCTX 69 OSSL_FUNC_kdf_freectx OSSL_FUNC_KDF_FREECTX 70 OSSL_FUNC_kdf_dupctx OSSL_FUNC_KDF_DUPCTX 71 72 OSSL_FUNC_kdf_reset OSSL_FUNC_KDF_RESET 73 OSSL_FUNC_kdf_derive OSSL_FUNC_KDF_DERIVE 74 75 OSSL_FUNC_kdf_get_params OSSL_FUNC_KDF_GET_PARAMS 76 OSSL_FUNC_kdf_get_ctx_params OSSL_FUNC_KDF_GET_CTX_PARAMS 77 OSSL_FUNC_kdf_set_ctx_params OSSL_FUNC_KDF_SET_CTX_PARAMS 78 79 OSSL_FUNC_kdf_gettable_params OSSL_FUNC_KDF_GETTABLE_PARAMS 80 OSSL_FUNC_kdf_gettable_ctx_params OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS 81 OSSL_FUNC_kdf_settable_ctx_params OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS 82 83A KDF algorithm implementation may not implement all of these functions. 84In order to be a consistent set of functions, at least the following functions 85must be implemented: OSSL_FUNC_kdf_newctx(), OSSL_FUNC_kdf_freectx(), 86OSSL_FUNC_kdf_set_ctx_params(), OSSL_FUNC_kdf_derive(). 87All other functions are optional. 88 89=head2 Context Management Functions 90 91OSSL_FUNC_kdf_newctx() should create and return a pointer to a provider side 92structure for holding context information during a KDF operation. 93A pointer to this context will be passed back in a number of the other KDF 94operation function calls. 95The parameter I<provctx> is the provider context generated during provider 96initialisation (see L<provider(7)>). 97 98OSSL_FUNC_kdf_freectx() is passed a pointer to the provider side KDF context in 99the I<kctx> parameter. 100If it receives NULL as I<kctx> value, it should not do anything other than 101return. 102This function should free any resources associated with that context. 103 104OSSL_FUNC_kdf_dupctx() should duplicate the provider side KDF context in the 105I<kctx> parameter and return the duplicate copy. 106 107=head2 Encryption/Decryption Functions 108 109OSSL_FUNC_kdf_reset() initialises a KDF operation given a provider 110side KDF context in the I<kctx> parameter. 111 112OSSL_FUNC_kdf_derive() performs the KDF operation after processing the 113I<params> as per OSSL_FUNC_kdf_set_ctx_params(). 114The I<kctx> parameter contains a pointer to the provider side context. 115The resulting key of the desired I<keylen> should be written to I<key>. 116If the algorithm does not support the requested I<keylen> the function must 117return error. 118 119=head2 KDF Parameters 120 121See L<OSSL_PARAM(3)> for further details on the parameters structure used by 122these functions. 123 124OSSL_FUNC_kdf_get_params() gets details of parameter values associated with the 125provider algorithm and stores them in I<params>. 126 127OSSL_FUNC_kdf_set_ctx_params() sets KDF parameters associated with the given 128provider side KDF context I<kctx> to I<params>. 129Any parameter settings are additional to any that were previously set. 130Passing NULL for I<params> should return true. 131 132OSSL_FUNC_kdf_get_ctx_params() retrieves gettable parameter values associated 133with the given provider side KDF context I<kctx> and stores them in I<params>. 134Passing NULL for I<params> should return true. 135 136OSSL_FUNC_kdf_gettable_params(), OSSL_FUNC_kdf_gettable_ctx_params(), 137and OSSL_FUNC_kdf_settable_ctx_params() all return constant L<OSSL_PARAM(3)> 138arrays as descriptors of the parameters that OSSL_FUNC_kdf_get_params(), 139OSSL_FUNC_kdf_get_ctx_params(), and OSSL_FUNC_kdf_set_ctx_params() 140can handle, respectively. OSSL_FUNC_kdf_gettable_ctx_params() and 141OSSL_FUNC_kdf_settable_ctx_params() will return the parameters associated 142with the provider side context I<kctx> in its current state if it is 143not NULL. Otherwise, they return the parameters associated with the 144provider side algorithm I<provctx>. 145 146 147Parameters currently recognised by built-in KDFs are as follows. Not all 148parameters are relevant to, or are understood by all KDFs: 149 150=over 4 151 152=item "size" (B<OSSL_KDF_PARAM_SIZE>) <unsigned integer> 153 154Gets the output size from the associated KDF ctx. 155If the algorithm produces a variable amount of output, SIZE_MAX should be 156returned. 157If the input parameters required to calculate the fixed output size have not yet 158been supplied, 0 should be returned indicating an error. 159 160=item "key" (B<OSSL_KDF_PARAM_KEY>) <octet string> 161 162Sets the key in the associated KDF ctx. 163 164=item "secret" (B<OSSL_KDF_PARAM_SECRET>) <octet string> 165 166Sets the secret in the associated KDF ctx. 167 168=item "pass" (B<OSSL_KDF_PARAM_PASSWORD>) <octet string> 169 170Sets the password in the associated KDF ctx. 171 172=item "cipher" (B<OSSL_KDF_PARAM_CIPHER>) <UTF8 string> 173 174=item "digest" (B<OSSL_KDF_PARAM_DIGEST>) <UTF8 string> 175 176=item "mac" (B<OSSL_KDF_PARAM_MAC>) <UTF8 string> 177 178Sets the name of the underlying cipher, digest or MAC to be used. 179It must name a suitable algorithm for the KDF that's being used. 180 181=item "maclen" (B<OSSL_KDF_PARAM_MAC_SIZE>) <octet string> 182 183Sets the length of the MAC in the associated KDF ctx. 184 185=item "properties" (B<OSSL_KDF_PARAM_PROPERTIES>) <UTF8 string> 186 187Sets the properties to be queried when trying to fetch the underlying algorithm. 188This must be given together with the algorithm naming parameter to be 189considered valid. 190 191=item "iter" (B<OSSL_KDF_PARAM_ITER>) <unsigned integer> 192 193Sets the number of iterations in the associated KDF ctx. 194 195=item "mode" (B<OSSL_KDF_PARAM_MODE>) <UTF8 string> 196 197Sets the mode in the associated KDF ctx. 198 199=item "pkcs5" (B<OSSL_KDF_PARAM_PKCS5>) <integer> 200 201Enables or disables the SP800-132 compliance checks. 202A mode of 0 enables the compliance checks. 203 204The checks performed are: 205 206=over 4 207 208=item - the iteration count is at least 1000. 209 210=item - the salt length is at least 128 bits. 211 212=item - the derived key length is at least 112 bits. 213 214=back 215 216=item "ukm" (B<OSSL_KDF_PARAM_UKM>) <octet string> 217 218Sets an optional random string that is provided by the sender called 219"partyAInfo". In CMS this is the user keying material. 220 221 222=item "cekalg" (B<OSSL_KDF_PARAM_CEK_ALG>) <UTF8 string> 223 224Sets the CEK wrapping algorithm name in the associated KDF ctx. 225 226=item "n" (B<OSSL_KDF_PARAM_SCRYPT_N>) <unsigned integer> 227 228Sets the scrypt work factor parameter N in the associated KDF ctx. 229 230=item "r" (B<OSSL_KDF_PARAM_SCRYPT_R>) <unsigned integer> 231 232Sets the scrypt work factor parameter r in the associated KDF ctx. 233 234=item "p" (B<OSSL_KDF_PARAM_SCRYPT_P>) <unsigned integer> 235 236Sets the scrypt work factor parameter p in the associated KDF ctx. 237 238=item "maxmem_bytes" (B<OSSL_KDF_PARAM_SCRYPT_MAXMEM>) <unsigned integer> 239 240Sets the scrypt work factor parameter maxmem in the associated KDF ctx. 241 242=item "prefix" (B<OSSL_KDF_PARAM_PREFIX>) <octet string> 243 244Sets the prefix string using by the TLS 1.3 version of HKDF in the 245associated KDF ctx. 246 247=item "label" (B<OSSL_KDF_PARAM_LABEL>) <octet string> 248 249Sets the label string using by the TLS 1.3 version of HKDF in the 250associated KDF ctx. 251 252=item "data" (B<OSSL_KDF_PARAM_DATA>) <octet string> 253 254Sets the context string using by the TLS 1.3 version of HKDF in the 255associated KDF ctx. 256 257=item "info" (B<OSSL_KDF_PARAM_INFO>) <octet string> 258 259Sets the optional shared info in the associated KDF ctx. 260 261=item "seed" (B<OSSL_KDF_PARAM_SEED>) <octet string> 262 263Sets the IV in the associated KDF ctx. 264 265=item "xcghash" (B<OSSL_KDF_PARAM_SSHKDF_XCGHASH>) <octet string> 266 267Sets the xcghash in the associated KDF ctx. 268 269=item "session_id" (B<OSSL_KDF_PARAM_SSHKDF_SESSION_ID>) <octet string> 270 271Sets the session ID in the associated KDF ctx. 272 273=item "type" (B<OSSL_KDF_PARAM_SSHKDF_TYPE>) <UTF8 string> 274 275Sets the SSH KDF type parameter in the associated KDF ctx. 276There are six supported types: 277 278=over 4 279 280=item EVP_KDF_SSHKDF_TYPE_INITIAL_IV_CLI_TO_SRV 281 282The Initial IV from client to server. 283A single char of value 65 (ASCII char 'A'). 284 285=item EVP_KDF_SSHKDF_TYPE_INITIAL_IV_SRV_TO_CLI 286 287The Initial IV from server to client 288A single char of value 66 (ASCII char 'B'). 289 290=item EVP_KDF_SSHKDF_TYPE_ENCRYPTION_KEY_CLI_TO_SRV 291 292The Encryption Key from client to server 293A single char of value 67 (ASCII char 'C'). 294 295=item EVP_KDF_SSHKDF_TYPE_ENCRYPTION_KEY_SRV_TO_CLI 296 297The Encryption Key from server to client 298A single char of value 68 (ASCII char 'D'). 299 300=item EVP_KDF_SSHKDF_TYPE_INTEGRITY_KEY_CLI_TO_SRV 301 302The Integrity Key from client to server 303A single char of value 69 (ASCII char 'E'). 304 305=item EVP_KDF_SSHKDF_TYPE_INTEGRITY_KEY_SRV_TO_CLI 306 307The Integrity Key from client to server 308A single char of value 70 (ASCII char 'F'). 309 310=back 311 312=item "constant" (B<OSSL_KDF_PARAM_CONSTANT>) <octet string> 313 314Sets the constant value in the associated KDF ctx. 315 316=item "id" (B<OSSL_KDF_PARAM_PKCS12_ID>) <integer> 317 318Sets the intended usage of the output bits in the associated KDF ctx. 319It is defined as per RFC 7292 section B.3. 320 321=back 322 323=head1 RETURN VALUES 324 325OSSL_FUNC_kdf_newctx() and OSSL_FUNC_kdf_dupctx() should return the newly created 326provider side KDF context, or NULL on failure. 327 328OSSL_FUNC_kdf_derive(), OSSL_FUNC_kdf_get_params(), 329OSSL_FUNC_kdf_get_ctx_params() and OSSL_FUNC_kdf_set_ctx_params() should return 1 for 330success or 0 on error. 331 332OSSL_FUNC_kdf_gettable_params(), OSSL_FUNC_kdf_gettable_ctx_params() and 333OSSL_FUNC_kdf_settable_ctx_params() should return a constant L<OSSL_PARAM(3)> 334array, or NULL if none is offered. 335 336=head1 NOTES 337 338The KDF life-cycle is described in L<life_cycle-kdf(7)>. Providers should 339ensure that the various transitions listed there are supported. At some point 340the EVP layer will begin enforcing the listed transitions. 341 342=head1 SEE ALSO 343 344L<provider(7)>, L<life_cycle-kdf(7)>, L<EVP_KDF(3)>. 345 346=head1 HISTORY 347 348The provider KDF interface was introduced in OpenSSL 3.0. 349 350=head1 COPYRIGHT 351 352Copyright 2020-2023 The OpenSSL Project Authors. All Rights Reserved. 353 354Licensed under the Apache License 2.0 (the "License"). You may not use 355this file except in compliance with the License. You can obtain a copy 356in the file LICENSE in the source distribution or at 357L<https://www.openssl.org/source/license.html>. 358 359=cut 360