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     int is_kmac;
  66 } KDF_SSKDF;
  67
  68 #define SSKDF_MAX_INLEN (1<<30)
  69 #define SSKDF_KMAC128_DEFAULT_SALT_SIZE (168 - 4)
  70 #define SSKDF_KMAC256_DEFAULT_SALT_SIZE (136 - 4)
  71
  72 /* KMAC uses a Customisation string of 'KDF' */
  73 static const unsigned char kmac_custom_str[] = { 0x4B, 0x44, 0x46 };
  74
  75 static OSSL_FUNC_kdf_newctx_fn sskdf_new;
  76 static OSSL_FUNC_kdf_dupctx_fn sskdf_dup;
  77 static OSSL_FUNC_kdf_freectx_fn sskdf_free;
  78 static OSSL_FUNC_kdf_reset_fn sskdf_reset;
  79 static OSSL_FUNC_kdf_derive_fn sskdf_derive;
  80 static OSSL_FUNC_kdf_derive_fn x963kdf_derive;
  81 static OSSL_FUNC_kdf_settable_ctx_params_fn sskdf_settable_ctx_params;
  82 static OSSL_FUNC_kdf_set_ctx_params_fn sskdf_set_ctx_params;
  83 static OSSL_FUNC_kdf_gettable_ctx_params_fn sskdf_gettable_ctx_params;
  84 static OSSL_FUNC_kdf_get_ctx_params_fn sskdf_get_ctx_params;
  85
  86 /*
  87  * Refer to https://csrc.nist.gov/publications/detail/sp/800-56c/rev-1/final
  88  * Section 4. One-Step Key Derivation using H(x) = hash(x)
  89  * Note: X9.63 also uses this code with the only difference being that the
  90  * counter is appended to the secret 'z'.
  91  * i.e.
  92  *   result[i] = Hash(counter || z || info) for One Step OR
  93  *   result[i] = Hash(z || counter || info) for X9.63.
  94  */
  95 static int SSKDF_hash_kdm(const EVP_MD *kdf_md,
  96                           const unsigned char *z, size_t z_len,
  97                           const unsigned char *info, size_t info_len,
  98                           unsigned int append_ctr,
  99                           unsigned char *derived_key, size_t derived_key_len)
 100 {
 101     int ret = 0, hlen;
 102     size_t counter, out_len, len = derived_key_len;
 103     unsigned char c[4];
 104     unsigned char mac[EVP_MAX_MD_SIZE];
 105     unsigned char *out = derived_key;
 106     EVP_MD_CTX *ctx = NULL, *ctx_init = NULL;
 107
 108     if (z_len > SSKDF_MAX_INLEN || info_len > SSKDF_MAX_INLEN
 109             || derived_key_len > SSKDF_MAX_INLEN
 110             || derived_key_len == 0)
 111         return 0;
 112
 113     hlen = EVP_MD_get_size(kdf_md);
 114     if (hlen <= 0)
 115         return 0;
 116     out_len = (size_t)hlen;
 117
 118     ctx = EVP_MD_CTX_create();
 119     ctx_init = EVP_MD_CTX_create();
 120     if (ctx == NULL || ctx_init == NULL)
 121         goto end;
 122
 123     if (!EVP_DigestInit(ctx_init, kdf_md))
 124         goto end;
 125
 126     for (counter = 1;; counter++) {
 127         c[0] = (unsigned char)((counter >> 24) & 0xff);
 128         c[1] = (unsigned char)((counter >> 16) & 0xff);
 129         c[2] = (unsigned char)((counter >> 8) & 0xff);
 130         c[3] = (unsigned char)(counter & 0xff);
 131
 132         if (!(EVP_MD_CTX_copy_ex(ctx, ctx_init)
 133                 && (append_ctr || EVP_DigestUpdate(ctx, c, sizeof(c)))
 134                 && EVP_DigestUpdate(ctx, z, z_len)
 135                 && (!append_ctr || EVP_DigestUpdate(ctx, c, sizeof(c)))
 136                 && EVP_DigestUpdate(ctx, info, info_len)))
 137             goto end;
 138         if (len >= out_len) {
 139             if (!EVP_DigestFinal_ex(ctx, out, NULL))
 140                 goto end;
 141             out += out_len;
 142             len -= out_len;
 143             if (len == 0)
 144                 break;
 145         } else {
 146             if (!EVP_DigestFinal_ex(ctx, mac, NULL))
 147                 goto end;
 148             memcpy(out, mac, len);
 149             break;
 150         }
 151     }
 152     ret = 1;
 153 end:
 154     EVP_MD_CTX_destroy(ctx);
 155     EVP_MD_CTX_destroy(ctx_init);
 156     OPENSSL_cleanse(mac, sizeof(mac));
 157     return ret;
 158 }
 159
 160 static int kmac_init(EVP_MAC_CTX *ctx, const unsigned char *custom,
 161                      size_t custom_len, size_t kmac_out_len,
 162                      size_t derived_key_len, unsigned char **out)
 163 {
 164     OSSL_PARAM params[2];
 165
 166     /* Only KMAC has custom data - so return if not KMAC */
 167     if (custom == NULL)
 168         return 1;
 169
 170     params[0] = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_CUSTOM,
 171                                                   (void *)custom, custom_len);
 172     params[1] = OSSL_PARAM_construct_end();
 173
 174     if (!EVP_MAC_CTX_set_params(ctx, params))
 175         return 0;
 176
 177     /* By default only do one iteration if kmac_out_len is not specified */
 178     if (kmac_out_len == 0)
 179         kmac_out_len = derived_key_len;
 180     /* otherwise check the size is valid */
 181     else if (!(kmac_out_len == derived_key_len
 182             || kmac_out_len == 20
 183             || kmac_out_len == 28
 184             || kmac_out_len == 32
 185             || kmac_out_len == 48
 186             || kmac_out_len == 64))
 187         return 0;
 188
 189     params[0] = OSSL_PARAM_construct_size_t(OSSL_MAC_PARAM_SIZE,
 190                                             &kmac_out_len);
 191
 192     if (EVP_MAC_CTX_set_params(ctx, params) <= 0)
 193         return 0;
 194
 195     /*
 196      * For kmac the output buffer can be larger than EVP_MAX_MD_SIZE: so
 197      * alloc a buffer for this case.
 198      */
 199     if (kmac_out_len > EVP_MAX_MD_SIZE) {
 200         *out = OPENSSL_zalloc(kmac_out_len);
 201         if (*out == NULL)
 202             return 0;
 203     }
 204     return 1;
 205 }
 206
 207 /*
 208  * Refer to https://csrc.nist.gov/publications/detail/sp/800-56c/rev-1/final
 209  * Section 4. One-Step Key Derivation using MAC: i.e either
 210  *     H(x) = HMAC-hash(salt, x) OR
 211  *     H(x) = KMAC#(salt, x, outbits, CustomString='KDF')
 212  */
 213 static int SSKDF_mac_kdm(EVP_MAC_CTX *ctx_init,
 214                          const unsigned char *kmac_custom,
 215                          size_t kmac_custom_len, size_t kmac_out_len,
 216                          const unsigned char *salt, size_t salt_len,
 217                          const unsigned char *z, size_t z_len,
 218                          const unsigned char *info, size_t info_len,
 219                          unsigned char *derived_key, size_t derived_key_len)
 220 {
 221     int ret = 0;
 222     size_t counter, out_len, len;
 223     unsigned char c[4];
 224     unsigned char mac_buf[EVP_MAX_MD_SIZE];
 225     unsigned char *out = derived_key;
 226     EVP_MAC_CTX *ctx = NULL;
 227     unsigned char *mac = mac_buf, *kmac_buffer = NULL;
 228
 229     if (z_len > SSKDF_MAX_INLEN || info_len > SSKDF_MAX_INLEN
 230             || derived_key_len > SSKDF_MAX_INLEN
 231             || derived_key_len == 0)
 232         return 0;
 233
 234     if (!kmac_init(ctx_init, kmac_custom, kmac_custom_len, kmac_out_len,
 235                    derived_key_len, &kmac_buffer))
 236         goto end;
 237     if (kmac_buffer != NULL)
 238         mac = kmac_buffer;
 239
 240     if (!EVP_MAC_init(ctx_init, salt, salt_len, NULL))
 241         goto end;
 242
 243     out_len = EVP_MAC_CTX_get_mac_size(ctx_init); /* output size */
 244     if (out_len <= 0 || (mac == mac_buf && out_len > sizeof(mac_buf)))
 245         goto end;
 246     len = derived_key_len;
 247
 248     for (counter = 1;; counter++) {
 249         c[0] = (unsigned char)((counter >> 24) & 0xff);
 250         c[1] = (unsigned char)((counter >> 16) & 0xff);
 251         c[2] = (unsigned char)((counter >> 8) & 0xff);
 252         c[3] = (unsigned char)(counter & 0xff);
 253
 254         ctx = EVP_MAC_CTX_dup(ctx_init);
 255         if (!(ctx != NULL
 256                 && EVP_MAC_update(ctx, c, sizeof(c))
 257                 && EVP_MAC_update(ctx, z, z_len)
 258                 && EVP_MAC_update(ctx, info, info_len)))
 259             goto end;
 260         if (len >= out_len) {
 261             if (!EVP_MAC_final(ctx, out, NULL, len))
 262                 goto end;
 263             out += out_len;
 264             len -= out_len;
 265             if (len == 0)
 266                 break;
 267         } else {
 268             if (!EVP_MAC_final(ctx, mac, NULL, out_len))
 269                 goto end;
 270             memcpy(out, mac, len);
 271             break;
 272         }
 273         EVP_MAC_CTX_free(ctx);
 274         ctx = NULL;
 275     }
 276     ret = 1;
 277 end:
 278     if (kmac_buffer != NULL)
 279         OPENSSL_clear_free(kmac_buffer, kmac_out_len);
 280     else
 281         OPENSSL_cleanse(mac_buf, sizeof(mac_buf));
 282
 283     EVP_MAC_CTX_free(ctx);
 284     return ret;
 285 }
 286
 287 static void *sskdf_new(void *provctx)
 288 {
 289     KDF_SSKDF *ctx;
 290
 291     if (!ossl_prov_is_running())
 292         return NULL;
 293
 294     if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) != NULL)
 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         dest->is_kmac = src->is_kmac;
 345     }
 346     return dest;
 347
 348  err:
 349     sskdf_free(dest);
 350     return NULL;
 351 }
 352
 353 static int sskdf_set_buffer(unsigned char **out, size_t *out_len,
 354                             const OSSL_PARAM *p)
 355 {
 356     if (p->data == NULL || p->data_size == 0)
 357         return 1;
 358     OPENSSL_free(*out);
 359     *out = NULL;
 360     return OSSL_PARAM_get_octet_string(p, (void **)out, 0, out_len);
 361 }
 362
 363 static size_t sskdf_size(KDF_SSKDF *ctx)
 364 {
 365     int len;
 366     const EVP_MD *md = NULL;
 367
 368     if (ctx->is_kmac)
 369         return SIZE_MAX;
 370
 371     md = ossl_prov_digest_md(&ctx->digest);
 372     if (md == NULL) {
 373         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 374         return 0;
 375     }
 376     len = EVP_MD_get_size(md);
 377     return (len <= 0) ? 0 : (size_t)len;
 378 }
 379
 380 static int sskdf_derive(void *vctx, unsigned char *key, size_t keylen,
 381                         const OSSL_PARAM params[])
 382 {
 383     KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
 384     const EVP_MD *md;
 385
 386     if (!ossl_prov_is_running() || !sskdf_set_ctx_params(ctx, params))
 387         return 0;
 388     if (ctx->secret == NULL) {
 389         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
 390         return 0;
 391     }
 392     md = ossl_prov_digest_md(&ctx->digest);
 393
 394     if (ctx->macctx != NULL) {
 395         /* H(x) = KMAC or H(x) = HMAC */
 396         int ret;
 397         const unsigned char *custom = NULL;
 398         size_t custom_len = 0;
 399         int default_salt_len;
 400         EVP_MAC *mac = EVP_MAC_CTX_get0_mac(ctx->macctx);
 401
 402         if (EVP_MAC_is_a(mac, OSSL_MAC_NAME_HMAC)) {
 403             /* H(x) = HMAC(x, salt, hash) */
 404             if (md == NULL) {
 405                 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 406                 return 0;
 407             }
 408             default_salt_len = EVP_MD_get_size(md);
 409             if (default_salt_len <= 0)
 410                 return 0;
 411         } else if (ctx->is_kmac) {
 412             /* H(x) = KMACzzz(x, salt, custom) */
 413             custom = kmac_custom_str;
 414             custom_len = sizeof(kmac_custom_str);
 415             if (EVP_MAC_is_a(mac, OSSL_MAC_NAME_KMAC128))
 416                 default_salt_len = SSKDF_KMAC128_DEFAULT_SALT_SIZE;
 417             else
 418                 default_salt_len = SSKDF_KMAC256_DEFAULT_SALT_SIZE;
 419         } else {
 420             ERR_raise(ERR_LIB_PROV, PROV_R_UNSUPPORTED_MAC_TYPE);
 421             return 0;
 422         }
 423         /* If no salt is set then use a default_salt of zeros */
 424         if (ctx->salt == NULL || ctx->salt_len <= 0) {
 425             ctx->salt = OPENSSL_zalloc(default_salt_len);
 426             if (ctx->salt == NULL)
 427                 return 0;
 428             ctx->salt_len = default_salt_len;
 429         }
 430         ret = SSKDF_mac_kdm(ctx->macctx,
 431                             custom, custom_len, ctx->out_len,
 432                             ctx->salt, ctx->salt_len,
 433                             ctx->secret, ctx->secret_len,
 434                             ctx->info, ctx->info_len, key, keylen);
 435         return ret;
 436     } else {
 437         /* H(x) = hash */
 438         if (md == NULL) {
 439             ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 440             return 0;
 441         }
 442         return SSKDF_hash_kdm(md, ctx->secret, ctx->secret_len,
 443                               ctx->info, ctx->info_len, 0, key, keylen);
 444     }
 445 }
 446
 447 static int x963kdf_derive(void *vctx, unsigned char *key, size_t keylen,
 448                           const OSSL_PARAM params[])
 449 {
 450     KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
 451     const EVP_MD *md;
 452
 453     if (!ossl_prov_is_running() || !sskdf_set_ctx_params(ctx, params))
 454         return 0;
 455
 456     if (ctx->secret == NULL) {
 457         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
 458         return 0;
 459     }
 460
 461     if (ctx->macctx != NULL) {
 462         ERR_raise(ERR_LIB_PROV, PROV_R_NOT_SUPPORTED);
 463         return 0;
 464     }
 465
 466     /* H(x) = hash */
 467     md = ossl_prov_digest_md(&ctx->digest);
 468     if (md == NULL) {
 469         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 470         return 0;
 471     }
 472
 473     return SSKDF_hash_kdm(md, ctx->secret, ctx->secret_len,
 474                           ctx->info, ctx->info_len, 1, key, keylen);
 475 }
 476
 477 static int sskdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
 478 {
 479     const OSSL_PARAM *p;
 480     KDF_SSKDF *ctx = vctx;
 481     OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
 482     size_t sz;
 483
 484     if (params == NULL)
 485         return 1;
 486
 487     if (!ossl_prov_macctx_load_from_params(&ctx->macctx, params,
 488                                            NULL, NULL, NULL, libctx))
 489         return 0;
 490    if (ctx->macctx != NULL) {
 491         if (EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->macctx),
 492                          OSSL_MAC_NAME_KMAC128)
 493             || EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->macctx),
 494                             OSSL_MAC_NAME_KMAC256)) {
 495             ctx->is_kmac = 1;
 496         }
 497    }
 498
 499    if (!ossl_prov_digest_load_from_params(&ctx->digest, params, libctx))
 500        return 0;
 501
 502     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SECRET)) != NULL
 503         || (p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)
 504         if (!sskdf_set_buffer(&ctx->secret, &ctx->secret_len, p))
 505             return 0;
 506
 507     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_INFO)) != NULL)
 508         if (!sskdf_set_buffer(&ctx->info, &ctx->info_len, p))
 509             return 0;
 510
 511     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SALT)) != NULL)
 512         if (!sskdf_set_buffer(&ctx->salt, &ctx->salt_len, p))
 513             return 0;
 514
 515     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MAC_SIZE))
 516         != NULL) {
 517         if (!OSSL_PARAM_get_size_t(p, &sz) || sz == 0)
 518             return 0;
 519         ctx->out_len = sz;
 520     }
 521     return 1;
 522 }
 523
 524 static const OSSL_PARAM *sskdf_settable_ctx_params(ossl_unused void *ctx,
 525                                                    ossl_unused void *provctx)
 526 {
 527     static const OSSL_PARAM known_settable_ctx_params[] = {
 528         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SECRET, NULL, 0),
 529         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
 530         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_INFO, NULL, 0),
 531         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
 532         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
 533         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MAC, NULL, 0),
 534         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0),
 535         OSSL_PARAM_size_t(OSSL_KDF_PARAM_MAC_SIZE, NULL),
 536         OSSL_PARAM_END
 537     };
 538     return known_settable_ctx_params;
 539 }
 540
 541 static int sskdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
 542 {
 543     KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
 544     OSSL_PARAM *p;
 545
 546     if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
 547         return OSSL_PARAM_set_size_t(p, sskdf_size(ctx));
 548     return -2;
 549 }
 550
 551 static const OSSL_PARAM *sskdf_gettable_ctx_params(ossl_unused void *ctx,
 552                                                    ossl_unused void *provctx)
 553 {
 554     static const OSSL_PARAM known_gettable_ctx_params[] = {
 555         OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
 556         OSSL_PARAM_END
 557     };
 558     return known_gettable_ctx_params;
 559 }
 560
 561 const OSSL_DISPATCH ossl_kdf_sskdf_functions[] = {
 562     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))sskdf_new },
 563     { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))sskdf_dup },
 564     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))sskdf_free },
 565     { OSSL_FUNC_KDF_RESET, (void(*)(void))sskdf_reset },
 566     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))sskdf_derive },
 567     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 568       (void(*)(void))sskdf_settable_ctx_params },
 569     { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))sskdf_set_ctx_params },
 570     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 571       (void(*)(void))sskdf_gettable_ctx_params },
 572     { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))sskdf_get_ctx_params },
 573     { 0, NULL }
 574 };
 575
 576 const OSSL_DISPATCH ossl_kdf_x963_kdf_functions[] = {
 577     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))sskdf_new },
 578     { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))sskdf_dup },
 579     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))sskdf_free },
 580     { OSSL_FUNC_KDF_RESET, (void(*)(void))sskdf_reset },
 581     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))x963kdf_derive },
 582     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 583       (void(*)(void))sskdf_settable_ctx_params },
 584     { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))sskdf_set_ctx_params },
 585     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 586       (void(*)(void))sskdf_gettable_ctx_params },
 587     { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))sskdf_get_ctx_params },
 588     { 0, NULL }
 589 };