providers/implementations/kdfs/sskdf.c

   1 /*
   2  * Copyright 2019-2022 The OpenSSL Project Authors. All Rights Reserved.
   3  * Copyright (c) 2019, Oracle and/or its affiliates.  All rights reserved.
   4  *
   5  * Licensed under the Apache License 2.0 (the "License").  You may not use
   6  * this file except in compliance with the License.  You can obtain a copy
   7  * in the file LICENSE in the source distribution or at
   8  * https://www.openssl.org/source/license.html
   9  */
  10
  11 /*
  12  * Refer to https://csrc.nist.gov/publications/detail/sp/800-56c/rev-1/final
  13  * Section 4.1.
  14  *
  15  * The Single Step KDF algorithm is given by:
  16  *
  17  * Result(0) = empty bit string (i.e., the null string).
  18  * For i = 1 to reps, do the following:
  19  *   Increment counter by 1.
  20  *   Result(i) = Result(i - 1) || H(counter || Z || FixedInfo).
  21  * DKM = LeftmostBits(Result(reps), L))
  22  *
  23  * NOTES:
  24  *   Z is a shared secret required to produce the derived key material.
  25  *   counter is a 4 byte buffer.
  26  *   FixedInfo is a bit string containing context specific data.
  27  *   DKM is the output derived key material.
  28  *   L is the required size of the DKM.
  29  *   reps = [L / H_outputBits]
  30  *   H(x) is the auxiliary function that can be either a hash, HMAC or KMAC.
  31  *   H_outputBits is the length of the output of the auxiliary function H(x).
  32  *
  33  * Currently there is not a comprehensive list of test vectors for this
  34  * algorithm, especially for H(x) = HMAC and H(x) = KMAC.
  35  * Test vectors for H(x) = Hash are indirectly used by CAVS KAS tests.
  36  */
  37 #include <stdlib.h>
  38 #include <stdarg.h>
  39 #include <string.h>
  40 #include <openssl/hmac.h>
  41 #include <openssl/evp.h>
  42 #include <openssl/kdf.h>
  43 #include <openssl/core_names.h>
  44 #include <openssl/params.h>
  45 #include <openssl/proverr.h>
  46 #include "internal/cryptlib.h"
  47 #include "internal/numbers.h"
  48 #include "crypto/evp.h"
  49 #include "prov/provider_ctx.h"
  50 #include "prov/providercommon.h"
  51 #include "prov/implementations.h"
  52 #include "prov/provider_util.h"
  53
  54 typedef struct {
  55     void *provctx;
  56     EVP_MAC_CTX *macctx;         /* H(x) = HMAC_hash OR H(x) = KMAC */
  57     PROV_DIGEST digest;          /* H(x) = hash(x) */
  58     unsigned char *secret;
  59     size_t secret_len;
  60     unsigned char *info;
  61     size_t info_len;
  62     unsigned char *salt;
  63     size_t salt_len;
  64     size_t out_len; /* optional KMAC parameter */
  65 } KDF_SSKDF;
  66
  67 #define SSKDF_MAX_INLEN (1<<30)
  68 #define SSKDF_KMAC128_DEFAULT_SALT_SIZE (168 - 4)
  69 #define SSKDF_KMAC256_DEFAULT_SALT_SIZE (136 - 4)
  70
  71 /* KMAC uses a Customisation string of 'KDF' */
  72 static const unsigned char kmac_custom_str[] = { 0x4B, 0x44, 0x46 };
  73
  74 static OSSL_FUNC_kdf_newctx_fn sskdf_new;
  75 static OSSL_FUNC_kdf_dupctx_fn sskdf_dup;
  76 static OSSL_FUNC_kdf_freectx_fn sskdf_free;
  77 static OSSL_FUNC_kdf_reset_fn sskdf_reset;
  78 static OSSL_FUNC_kdf_derive_fn sskdf_derive;
  79 static OSSL_FUNC_kdf_derive_fn x963kdf_derive;
  80 static OSSL_FUNC_kdf_settable_ctx_params_fn sskdf_settable_ctx_params;
  81 static OSSL_FUNC_kdf_set_ctx_params_fn sskdf_set_ctx_params;
  82 static OSSL_FUNC_kdf_gettable_ctx_params_fn sskdf_gettable_ctx_params;
  83 static OSSL_FUNC_kdf_get_ctx_params_fn sskdf_get_ctx_params;
  84
  85 /*
  86  * Refer to https://csrc.nist.gov/publications/detail/sp/800-56c/rev-1/final
  87  * Section 4. One-Step Key Derivation using H(x) = hash(x)
  88  * Note: X9.63 also uses this code with the only difference being that the
  89  * counter is appended to the secret 'z'.
  90  * i.e.
  91  *   result[i] = Hash(counter || z || info) for One Step OR
  92  *   result[i] = Hash(z || counter || info) for X9.63.
  93  */
  94 static int SSKDF_hash_kdm(const EVP_MD *kdf_md,
  95                           const unsigned char *z, size_t z_len,
  96                           const unsigned char *info, size_t info_len,
  97                           unsigned int append_ctr,
  98                           unsigned char *derived_key, size_t derived_key_len)
  99 {
 100     int ret = 0, hlen;
 101     size_t counter, out_len, len = derived_key_len;
 102     unsigned char c[4];
 103     unsigned char mac[EVP_MAX_MD_SIZE];
 104     unsigned char *out = derived_key;
 105     EVP_MD_CTX *ctx = NULL, *ctx_init = NULL;
 106
 107     if (z_len > SSKDF_MAX_INLEN || info_len > SSKDF_MAX_INLEN
 108             || derived_key_len > SSKDF_MAX_INLEN
 109             || derived_key_len == 0)
 110         return 0;
 111
 112     hlen = EVP_MD_get_size(kdf_md);
 113     if (hlen <= 0)
 114         return 0;
 115     out_len = (size_t)hlen;
 116
 117     ctx = EVP_MD_CTX_create();
 118     ctx_init = EVP_MD_CTX_create();
 119     if (ctx == NULL || ctx_init == NULL)
 120         goto end;
 121
 122     if (!EVP_DigestInit(ctx_init, kdf_md))
 123         goto end;
 124
 125     for (counter = 1;; counter++) {
 126         c[0] = (unsigned char)((counter >> 24) & 0xff);
 127         c[1] = (unsigned char)((counter >> 16) & 0xff);
 128         c[2] = (unsigned char)((counter >> 8) & 0xff);
 129         c[3] = (unsigned char)(counter & 0xff);
 130
 131         if (!(EVP_MD_CTX_copy_ex(ctx, ctx_init)
 132                 && (append_ctr || EVP_DigestUpdate(ctx, c, sizeof(c)))
 133                 && EVP_DigestUpdate(ctx, z, z_len)
 134                 && (!append_ctr || EVP_DigestUpdate(ctx, c, sizeof(c)))
 135                 && EVP_DigestUpdate(ctx, info, info_len)))
 136             goto end;
 137         if (len >= out_len) {
 138             if (!EVP_DigestFinal_ex(ctx, out, NULL))
 139                 goto end;
 140             out += out_len;
 141             len -= out_len;
 142             if (len == 0)
 143                 break;
 144         } else {
 145             if (!EVP_DigestFinal_ex(ctx, mac, NULL))
 146                 goto end;
 147             memcpy(out, mac, len);
 148             break;
 149         }
 150     }
 151     ret = 1;
 152 end:
 153     EVP_MD_CTX_destroy(ctx);
 154     EVP_MD_CTX_destroy(ctx_init);
 155     OPENSSL_cleanse(mac, sizeof(mac));
 156     return ret;
 157 }
 158
 159 static int kmac_init(EVP_MAC_CTX *ctx, const unsigned char *custom,
 160                      size_t custom_len, size_t kmac_out_len,
 161                      size_t derived_key_len, unsigned char **out)
 162 {
 163     OSSL_PARAM params[2];
 164
 165     /* Only KMAC has custom data - so return if not KMAC */
 166     if (custom == NULL)
 167         return 1;
 168
 169     params[0] = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_CUSTOM,
 170                                                   (void *)custom, custom_len);
 171     params[1] = OSSL_PARAM_construct_end();
 172
 173     if (!EVP_MAC_CTX_set_params(ctx, params))
 174         return 0;
 175
 176     /* By default only do one iteration if kmac_out_len is not specified */
 177     if (kmac_out_len == 0)
 178         kmac_out_len = derived_key_len;
 179     /* otherwise check the size is valid */
 180     else if (!(kmac_out_len == derived_key_len
 181             || kmac_out_len == 20
 182             || kmac_out_len == 28
 183             || kmac_out_len == 32
 184             || kmac_out_len == 48
 185             || kmac_out_len == 64))
 186         return 0;
 187
 188     params[0] = OSSL_PARAM_construct_size_t(OSSL_MAC_PARAM_SIZE,
 189                                             &kmac_out_len);
 190
 191     if (EVP_MAC_CTX_set_params(ctx, params) <= 0)
 192         return 0;
 193
 194     /*
 195      * For kmac the output buffer can be larger than EVP_MAX_MD_SIZE: so
 196      * alloc a buffer for this case.
 197      */
 198     if (kmac_out_len > EVP_MAX_MD_SIZE) {
 199         *out = OPENSSL_zalloc(kmac_out_len);
 200         if (*out == NULL)
 201             return 0;
 202     }
 203     return 1;
 204 }
 205
 206 /*
 207  * Refer to https://csrc.nist.gov/publications/detail/sp/800-56c/rev-1/final
 208  * Section 4. One-Step Key Derivation using MAC: i.e either
 209  *     H(x) = HMAC-hash(salt, x) OR
 210  *     H(x) = KMAC#(salt, x, outbits, CustomString='KDF')
 211  */
 212 static int SSKDF_mac_kdm(EVP_MAC_CTX *ctx_init,
 213                          const unsigned char *kmac_custom,
 214                          size_t kmac_custom_len, size_t kmac_out_len,
 215                          const unsigned char *salt, size_t salt_len,
 216                          const unsigned char *z, size_t z_len,
 217                          const unsigned char *info, size_t info_len,
 218                          unsigned char *derived_key, size_t derived_key_len)
 219 {
 220     int ret = 0;
 221     size_t counter, out_len, len;
 222     unsigned char c[4];
 223     unsigned char mac_buf[EVP_MAX_MD_SIZE];
 224     unsigned char *out = derived_key;
 225     EVP_MAC_CTX *ctx = NULL;
 226     unsigned char *mac = mac_buf, *kmac_buffer = NULL;
 227
 228     if (z_len > SSKDF_MAX_INLEN || info_len > SSKDF_MAX_INLEN
 229             || derived_key_len > SSKDF_MAX_INLEN
 230             || derived_key_len == 0)
 231         return 0;
 232
 233     if (!kmac_init(ctx_init, kmac_custom, kmac_custom_len, kmac_out_len,
 234                    derived_key_len, &kmac_buffer))
 235         goto end;
 236     if (kmac_buffer != NULL)
 237         mac = kmac_buffer;
 238
 239     if (!EVP_MAC_init(ctx_init, salt, salt_len, NULL))
 240         goto end;
 241
 242     out_len = EVP_MAC_CTX_get_mac_size(ctx_init); /* output size */
 243     if (out_len <= 0 || (mac == mac_buf && out_len > sizeof(mac_buf)))
 244         goto end;
 245     len = derived_key_len;
 246
 247     for (counter = 1;; counter++) {
 248         c[0] = (unsigned char)((counter >> 24) & 0xff);
 249         c[1] = (unsigned char)((counter >> 16) & 0xff);
 250         c[2] = (unsigned char)((counter >> 8) & 0xff);
 251         c[3] = (unsigned char)(counter & 0xff);
 252
 253         ctx = EVP_MAC_CTX_dup(ctx_init);
 254         if (!(ctx != NULL
 255                 && EVP_MAC_update(ctx, c, sizeof(c))
 256                 && EVP_MAC_update(ctx, z, z_len)
 257                 && EVP_MAC_update(ctx, info, info_len)))
 258             goto end;
 259         if (len >= out_len) {
 260             if (!EVP_MAC_final(ctx, out, NULL, len))
 261                 goto end;
 262             out += out_len;
 263             len -= out_len;
 264             if (len == 0)
 265                 break;
 266         } else {
 267             if (!EVP_MAC_final(ctx, mac, NULL, out_len))
 268                 goto end;
 269             memcpy(out, mac, len);
 270             break;
 271         }
 272         EVP_MAC_CTX_free(ctx);
 273         ctx = NULL;
 274     }
 275     ret = 1;
 276 end:
 277     if (kmac_buffer != NULL)
 278         OPENSSL_clear_free(kmac_buffer, kmac_out_len);
 279     else
 280         OPENSSL_cleanse(mac_buf, sizeof(mac_buf));
 281
 282     EVP_MAC_CTX_free(ctx);
 283     return ret;
 284 }
 285
 286 static void *sskdf_new(void *provctx)
 287 {
 288     KDF_SSKDF *ctx;
 289
 290     if (!ossl_prov_is_running())
 291         return NULL;
 292
 293     if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
 294         ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
 295     ctx->provctx = provctx;
 296     return ctx;
 297 }
 298
 299 static void sskdf_reset(void *vctx)
 300 {
 301     KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
 302     void *provctx = ctx->provctx;
 303
 304     EVP_MAC_CTX_free(ctx->macctx);
 305     ossl_prov_digest_reset(&ctx->digest);
 306     OPENSSL_clear_free(ctx->secret, ctx->secret_len);
 307     OPENSSL_clear_free(ctx->info, ctx->info_len);
 308     OPENSSL_clear_free(ctx->salt, ctx->salt_len);
 309     memset(ctx, 0, sizeof(*ctx));
 310     ctx->provctx = provctx;
 311 }
 312
 313 static void sskdf_free(void *vctx)
 314 {
 315     KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
 316
 317     if (ctx != NULL) {
 318         sskdf_reset(ctx);
 319         OPENSSL_free(ctx);
 320     }
 321 }
 322
 323 static void *sskdf_dup(void *vctx)
 324 {
 325     const KDF_SSKDF *src = (const KDF_SSKDF *)vctx;
 326     KDF_SSKDF *dest;
 327
 328     dest = sskdf_new(src->provctx);
 329     if (dest != NULL) {
 330         if (src->macctx != NULL) {
 331             dest->macctx = EVP_MAC_CTX_dup(src->macctx);
 332             if (dest->macctx == NULL)
 333                 goto err;
 334         }
 335         if (!ossl_prov_memdup(src->info, src->info_len,
 336                               &dest->info, &dest->info_len)
 337                 || !ossl_prov_memdup(src->salt, src->salt_len,
 338                                      &dest->salt , &dest->salt_len)
 339                 || !ossl_prov_memdup(src->secret, src->secret_len,
 340                                      &dest->secret, &dest->secret_len)
 341                 || !ossl_prov_digest_copy(&dest->digest, &src->digest))
 342             goto err;
 343         dest->out_len = src->out_len;
 344     }
 345     return dest;
 346
 347  err:
 348     sskdf_free(dest);
 349     return NULL;
 350 }
 351
 352 static int sskdf_set_buffer(unsigned char **out, size_t *out_len,
 353                             const OSSL_PARAM *p)
 354 {
 355     if (p->data == NULL || p->data_size == 0)
 356         return 1;
 357     OPENSSL_free(*out);
 358     *out = NULL;
 359     return OSSL_PARAM_get_octet_string(p, (void **)out, 0, out_len);
 360 }
 361
 362 static size_t sskdf_size(KDF_SSKDF *ctx)
 363 {
 364     int len;
 365     const EVP_MD *md = ossl_prov_digest_md(&ctx->digest);
 366
 367     if (md == NULL) {
 368         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 369         return 0;
 370     }
 371     len = EVP_MD_get_size(md);
 372     return (len <= 0) ? 0 : (size_t)len;
 373 }
 374
 375 static int sskdf_derive(void *vctx, unsigned char *key, size_t keylen,
 376                         const OSSL_PARAM params[])
 377 {
 378     KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
 379     const EVP_MD *md;
 380
 381     if (!ossl_prov_is_running() || !sskdf_set_ctx_params(ctx, params))
 382         return 0;
 383     if (ctx->secret == NULL) {
 384         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
 385         return 0;
 386     }
 387     md = ossl_prov_digest_md(&ctx->digest);
 388
 389     if (ctx->macctx != NULL) {
 390         /* H(x) = KMAC or H(x) = HMAC */
 391         int ret;
 392         const unsigned char *custom = NULL;
 393         size_t custom_len = 0;
 394         int default_salt_len;
 395         EVP_MAC *mac = EVP_MAC_CTX_get0_mac(ctx->macctx);
 396
 397         if (EVP_MAC_is_a(mac, OSSL_MAC_NAME_HMAC)) {
 398             /* H(x) = HMAC(x, salt, hash) */
 399             if (md == NULL) {
 400                 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 401                 return 0;
 402             }
 403             default_salt_len = EVP_MD_get_size(md);
 404             if (default_salt_len <= 0)
 405                 return 0;
 406         } else if (EVP_MAC_is_a(mac, OSSL_MAC_NAME_KMAC128)
 407                    || EVP_MAC_is_a(mac, OSSL_MAC_NAME_KMAC256)) {
 408             /* H(x) = KMACzzz(x, salt, custom) */
 409             custom = kmac_custom_str;
 410             custom_len = sizeof(kmac_custom_str);
 411             if (EVP_MAC_is_a(mac, OSSL_MAC_NAME_KMAC128))
 412                 default_salt_len = SSKDF_KMAC128_DEFAULT_SALT_SIZE;
 413             else
 414                 default_salt_len = SSKDF_KMAC256_DEFAULT_SALT_SIZE;
 415         } else {
 416             ERR_raise(ERR_LIB_PROV, PROV_R_UNSUPPORTED_MAC_TYPE);
 417             return 0;
 418         }
 419         /* If no salt is set then use a default_salt of zeros */
 420         if (ctx->salt == NULL || ctx->salt_len <= 0) {
 421             ctx->salt = OPENSSL_zalloc(default_salt_len);
 422             if (ctx->salt == NULL) {
 423                 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
 424                 return 0;
 425             }
 426             ctx->salt_len = default_salt_len;
 427         }
 428         ret = SSKDF_mac_kdm(ctx->macctx,
 429                             custom, custom_len, ctx->out_len,
 430                             ctx->salt, ctx->salt_len,
 431                             ctx->secret, ctx->secret_len,
 432                             ctx->info, ctx->info_len, key, keylen);
 433         return ret;
 434     } else {
 435         /* H(x) = hash */
 436         if (md == NULL) {
 437             ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 438             return 0;
 439         }
 440         return SSKDF_hash_kdm(md, ctx->secret, ctx->secret_len,
 441                               ctx->info, ctx->info_len, 0, key, keylen);
 442     }
 443 }
 444
 445 static int x963kdf_derive(void *vctx, unsigned char *key, size_t keylen,
 446                           const OSSL_PARAM params[])
 447 {
 448     KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
 449     const EVP_MD *md;
 450
 451     if (!ossl_prov_is_running() || !sskdf_set_ctx_params(ctx, params))
 452         return 0;
 453
 454     if (ctx->secret == NULL) {
 455         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
 456         return 0;
 457     }
 458
 459     if (ctx->macctx != NULL) {
 460         ERR_raise(ERR_LIB_PROV, PROV_R_NOT_SUPPORTED);
 461         return 0;
 462     }
 463
 464     /* H(x) = hash */
 465     md = ossl_prov_digest_md(&ctx->digest);
 466     if (md == NULL) {
 467         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 468         return 0;
 469     }
 470
 471     return SSKDF_hash_kdm(md, ctx->secret, ctx->secret_len,
 472                           ctx->info, ctx->info_len, 1, key, keylen);
 473 }
 474
 475 static int sskdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
 476 {
 477     const OSSL_PARAM *p;
 478     KDF_SSKDF *ctx = vctx;
 479     OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
 480     size_t sz;
 481
 482     if (params == NULL)
 483         return 1;
 484
 485     if (!ossl_prov_digest_load_from_params(&ctx->digest, params, libctx))
 486         return 0;
 487
 488     if (!ossl_prov_macctx_load_from_params(&ctx->macctx, params,
 489                                            NULL, NULL, NULL, libctx))
 490         return 0;
 491
 492     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SECRET)) != NULL
 493         || (p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)
 494         if (!sskdf_set_buffer(&ctx->secret, &ctx->secret_len, p))
 495             return 0;
 496
 497     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_INFO)) != NULL)
 498         if (!sskdf_set_buffer(&ctx->info, &ctx->info_len, p))
 499             return 0;
 500
 501     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SALT)) != NULL)
 502         if (!sskdf_set_buffer(&ctx->salt, &ctx->salt_len, p))
 503             return 0;
 504
 505     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MAC_SIZE))
 506         != NULL) {
 507         if (!OSSL_PARAM_get_size_t(p, &sz) || sz == 0)
 508             return 0;
 509         ctx->out_len = sz;
 510     }
 511     return 1;
 512 }
 513
 514 static const OSSL_PARAM *sskdf_settable_ctx_params(ossl_unused void *ctx,
 515                                                    ossl_unused void *provctx)
 516 {
 517     static const OSSL_PARAM known_settable_ctx_params[] = {
 518         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SECRET, NULL, 0),
 519         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
 520         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_INFO, NULL, 0),
 521         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
 522         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
 523         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MAC, NULL, 0),
 524         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0),
 525         OSSL_PARAM_size_t(OSSL_KDF_PARAM_MAC_SIZE, NULL),
 526         OSSL_PARAM_END
 527     };
 528     return known_settable_ctx_params;
 529 }
 530
 531 static int sskdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
 532 {
 533     KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
 534     OSSL_PARAM *p;
 535
 536     if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
 537         return OSSL_PARAM_set_size_t(p, sskdf_size(ctx));
 538     return -2;
 539 }
 540
 541 static const OSSL_PARAM *sskdf_gettable_ctx_params(ossl_unused void *ctx,
 542                                                    ossl_unused void *provctx)
 543 {
 544     static const OSSL_PARAM known_gettable_ctx_params[] = {
 545         OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
 546         OSSL_PARAM_END
 547     };
 548     return known_gettable_ctx_params;
 549 }
 550
 551 const OSSL_DISPATCH ossl_kdf_sskdf_functions[] = {
 552     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))sskdf_new },
 553     { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))sskdf_dup },
 554     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))sskdf_free },
 555     { OSSL_FUNC_KDF_RESET, (void(*)(void))sskdf_reset },
 556     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))sskdf_derive },
 557     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 558       (void(*)(void))sskdf_settable_ctx_params },
 559     { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))sskdf_set_ctx_params },
 560     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 561       (void(*)(void))sskdf_gettable_ctx_params },
 562     { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))sskdf_get_ctx_params },
 563     { 0, NULL }
 564 };
 565
 566 const OSSL_DISPATCH ossl_kdf_x963_kdf_functions[] = {
 567     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))sskdf_new },
 568     { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))sskdf_dup },
 569     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))sskdf_free },
 570     { OSSL_FUNC_KDF_RESET, (void(*)(void))sskdf_reset },
 571     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))x963kdf_derive },
 572     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 573       (void(*)(void))sskdf_settable_ctx_params },
 574     { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))sskdf_set_ctx_params },
 575     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 576       (void(*)(void))sskdf_gettable_ctx_params },
 577     { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))sskdf_get_ctx_params },
 578     { 0, NULL }
 579 };