providers/implementations/kdfs/sskdf.c

   1 /*
   2  * Copyright 2019-2021 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_freectx_fn sskdf_free;
  76 static OSSL_FUNC_kdf_reset_fn sskdf_reset;
  77 static OSSL_FUNC_kdf_derive_fn sskdf_derive;
  78 static OSSL_FUNC_kdf_derive_fn x963kdf_derive;
  79 static OSSL_FUNC_kdf_settable_ctx_params_fn sskdf_settable_ctx_params;
  80 static OSSL_FUNC_kdf_set_ctx_params_fn sskdf_set_ctx_params;
  81 static OSSL_FUNC_kdf_gettable_ctx_params_fn sskdf_gettable_ctx_params;
  82 static OSSL_FUNC_kdf_get_ctx_params_fn sskdf_get_ctx_params;
  83
  84 /*
  85  * Refer to https://csrc.nist.gov/publications/detail/sp/800-56c/rev-1/final
  86  * Section 4. One-Step Key Derivation using H(x) = hash(x)
  87  * Note: X9.63 also uses this code with the only difference being that the
  88  * counter is appended to the secret 'z'.
  89  * i.e.
  90  *   result[i] = Hash(counter || z || info) for One Step OR
  91  *   result[i] = Hash(z || counter || info) for X9.63.
  92  */
  93 static int SSKDF_hash_kdm(const EVP_MD *kdf_md,
  94                           const unsigned char *z, size_t z_len,
  95                           const unsigned char *info, size_t info_len,
  96                           unsigned int append_ctr,
  97                           unsigned char *derived_key, size_t derived_key_len)
  98 {
  99     int ret = 0, hlen;
 100     size_t counter, out_len, len = derived_key_len;
 101     unsigned char c[4];
 102     unsigned char mac[EVP_MAX_MD_SIZE];
 103     unsigned char *out = derived_key;
 104     EVP_MD_CTX *ctx = NULL, *ctx_init = NULL;
 105
 106     if (z_len > SSKDF_MAX_INLEN || info_len > SSKDF_MAX_INLEN
 107             || derived_key_len > SSKDF_MAX_INLEN
 108             || derived_key_len == 0)
 109         return 0;
 110
 111     hlen = EVP_MD_size(kdf_md);
 112     if (hlen <= 0)
 113         return 0;
 114     out_len = (size_t)hlen;
 115
 116     ctx = EVP_MD_CTX_create();
 117     ctx_init = EVP_MD_CTX_create();
 118     if (ctx == NULL || ctx_init == NULL)
 119         goto end;
 120
 121     if (!EVP_DigestInit(ctx_init, kdf_md))
 122         goto end;
 123
 124     for (counter = 1;; counter++) {
 125         c[0] = (unsigned char)((counter >> 24) & 0xff);
 126         c[1] = (unsigned char)((counter >> 16) & 0xff);
 127         c[2] = (unsigned char)((counter >> 8) & 0xff);
 128         c[3] = (unsigned char)(counter & 0xff);
 129
 130         if (!(EVP_MD_CTX_copy_ex(ctx, ctx_init)
 131                 && (append_ctr || EVP_DigestUpdate(ctx, c, sizeof(c)))
 132                 && EVP_DigestUpdate(ctx, z, z_len)
 133                 && (!append_ctr || EVP_DigestUpdate(ctx, c, sizeof(c)))
 134                 && EVP_DigestUpdate(ctx, info, info_len)))
 135             goto end;
 136         if (len >= out_len) {
 137             if (!EVP_DigestFinal_ex(ctx, out, NULL))
 138                 goto end;
 139             out += out_len;
 140             len -= out_len;
 141             if (len == 0)
 142                 break;
 143         } else {
 144             if (!EVP_DigestFinal_ex(ctx, mac, NULL))
 145                 goto end;
 146             memcpy(out, mac, len);
 147             break;
 148         }
 149     }
 150     ret = 1;
 151 end:
 152     EVP_MD_CTX_destroy(ctx);
 153     EVP_MD_CTX_destroy(ctx_init);
 154     OPENSSL_cleanse(mac, sizeof(mac));
 155     return ret;
 156 }
 157
 158 static int kmac_init(EVP_MAC_CTX *ctx, const unsigned char *custom,
 159                      size_t custom_len, size_t kmac_out_len,
 160                      size_t derived_key_len, unsigned char **out)
 161 {
 162     OSSL_PARAM params[2];
 163
 164     /* Only KMAC has custom data - so return if not KMAC */
 165     if (custom == NULL)
 166         return 1;
 167
 168     params[0] = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_CUSTOM,
 169                                                   (void *)custom, custom_len);
 170     params[1] = OSSL_PARAM_construct_end();
 171
 172     if (!EVP_MAC_CTX_set_params(ctx, params))
 173         return 0;
 174
 175     /* By default only do one iteration if kmac_out_len is not specified */
 176     if (kmac_out_len == 0)
 177         kmac_out_len = derived_key_len;
 178     /* otherwise check the size is valid */
 179     else if (!(kmac_out_len == derived_key_len
 180             || kmac_out_len == 20
 181             || kmac_out_len == 28
 182             || kmac_out_len == 32
 183             || kmac_out_len == 48
 184             || kmac_out_len == 64))
 185         return 0;
 186
 187     params[0] = OSSL_PARAM_construct_size_t(OSSL_MAC_PARAM_SIZE,
 188                                             &kmac_out_len);
 189
 190     if (EVP_MAC_CTX_set_params(ctx, params) <= 0)
 191         return 0;
 192
 193     /*
 194      * For kmac the output buffer can be larger than EVP_MAX_MD_SIZE: so
 195      * alloc a buffer for this case.
 196      */
 197     if (kmac_out_len > EVP_MAX_MD_SIZE) {
 198         *out = OPENSSL_zalloc(kmac_out_len);
 199         if (*out == NULL)
 200             return 0;
 201     }
 202     return 1;
 203 }
 204
 205 /*
 206  * Refer to https://csrc.nist.gov/publications/detail/sp/800-56c/rev-1/final
 207  * Section 4. One-Step Key Derivation using MAC: i.e either
 208  *     H(x) = HMAC-hash(salt, x) OR
 209  *     H(x) = KMAC#(salt, x, outbits, CustomString='KDF')
 210  */
 211 static int SSKDF_mac_kdm(EVP_MAC_CTX *ctx_init,
 212                          const unsigned char *kmac_custom,
 213                          size_t kmac_custom_len, size_t kmac_out_len,
 214                          const unsigned char *salt, size_t salt_len,
 215                          const unsigned char *z, size_t z_len,
 216                          const unsigned char *info, size_t info_len,
 217                          unsigned char *derived_key, size_t derived_key_len)
 218 {
 219     int ret = 0;
 220     size_t counter, out_len, len;
 221     unsigned char c[4];
 222     unsigned char mac_buf[EVP_MAX_MD_SIZE];
 223     unsigned char *out = derived_key;
 224     EVP_MAC_CTX *ctx = NULL;
 225     unsigned char *mac = mac_buf, *kmac_buffer = NULL;
 226     OSSL_PARAM params[2], *p = params;
 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     *p++ = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_KEY,
 234                                              (void *)salt, salt_len);
 235     *p = OSSL_PARAM_construct_end();
 236
 237     if (!EVP_MAC_CTX_set_params(ctx_init, params))
 238         goto end;
 239
 240     if (!kmac_init(ctx_init, kmac_custom, kmac_custom_len, kmac_out_len,
 241                    derived_key_len, &kmac_buffer))
 242         goto end;
 243     if (kmac_buffer != NULL)
 244         mac = kmac_buffer;
 245
 246     if (!EVP_MAC_init(ctx_init))
 247         goto end;
 248
 249     out_len = EVP_MAC_CTX_get_mac_size(ctx_init); /* output size */
 250     if (out_len <= 0)
 251         goto end;
 252     len = derived_key_len;
 253
 254     for (counter = 1;; counter++) {
 255         c[0] = (unsigned char)((counter >> 24) & 0xff);
 256         c[1] = (unsigned char)((counter >> 16) & 0xff);
 257         c[2] = (unsigned char)((counter >> 8) & 0xff);
 258         c[3] = (unsigned char)(counter & 0xff);
 259
 260         ctx = EVP_MAC_CTX_dup(ctx_init);
 261         if (!(ctx != NULL
 262                 && EVP_MAC_update(ctx, c, sizeof(c))
 263                 && EVP_MAC_update(ctx, z, z_len)
 264                 && EVP_MAC_update(ctx, info, info_len)))
 265             goto end;
 266         if (len >= out_len) {
 267             if (!EVP_MAC_final(ctx, out, NULL, len))
 268                 goto end;
 269             out += out_len;
 270             len -= out_len;
 271             if (len == 0)
 272                 break;
 273         } else {
 274             if (!EVP_MAC_final(ctx, mac, NULL, len))
 275                 goto end;
 276             memcpy(out, mac, len);
 277             break;
 278         }
 279         EVP_MAC_CTX_free(ctx);
 280         ctx = NULL;
 281     }
 282     ret = 1;
 283 end:
 284     if (kmac_buffer != NULL)
 285         OPENSSL_clear_free(kmac_buffer, kmac_out_len);
 286     else
 287         OPENSSL_cleanse(mac_buf, sizeof(mac_buf));
 288
 289     EVP_MAC_CTX_free(ctx);
 290     return ret;
 291 }
 292
 293 static void *sskdf_new(void *provctx)
 294 {
 295     KDF_SSKDF *ctx;
 296
 297     if (!ossl_prov_is_running())
 298         return NULL;
 299
 300     if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
 301         ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
 302     ctx->provctx = provctx;
 303     return ctx;
 304 }
 305
 306 static void sskdf_reset(void *vctx)
 307 {
 308     KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
 309     void *provctx = ctx->provctx;
 310
 311     EVP_MAC_CTX_free(ctx->macctx);
 312     ossl_prov_digest_reset(&ctx->digest);
 313     OPENSSL_clear_free(ctx->secret, ctx->secret_len);
 314     OPENSSL_clear_free(ctx->info, ctx->info_len);
 315     OPENSSL_clear_free(ctx->salt, ctx->salt_len);
 316     memset(ctx, 0, sizeof(*ctx));
 317     ctx->provctx = provctx;
 318 }
 319
 320 static void sskdf_free(void *vctx)
 321 {
 322     KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
 323
 324     if (ctx != NULL) {
 325         sskdf_reset(ctx);
 326         OPENSSL_free(ctx);
 327     }
 328 }
 329
 330 static int sskdf_set_buffer(unsigned char **out, size_t *out_len,
 331                             const OSSL_PARAM *p)
 332 {
 333     if (p->data == NULL || p->data_size == 0)
 334         return 1;
 335     OPENSSL_free(*out);
 336     *out = NULL;
 337     return OSSL_PARAM_get_octet_string(p, (void **)out, 0, out_len);
 338 }
 339
 340 static size_t sskdf_size(KDF_SSKDF *ctx)
 341 {
 342     int len;
 343     const EVP_MD *md = ossl_prov_digest_md(&ctx->digest);
 344
 345     if (md == NULL) {
 346         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 347         return 0;
 348     }
 349     len = EVP_MD_size(md);
 350     return (len <= 0) ? 0 : (size_t)len;
 351 }
 352
 353 static int sskdf_derive(void *vctx, unsigned char *key, size_t keylen)
 354 {
 355     KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
 356     const EVP_MD *md;
 357
 358     if (!ossl_prov_is_running())
 359         return 0;
 360     if (ctx->secret == NULL) {
 361         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
 362         return 0;
 363     }
 364     md = ossl_prov_digest_md(&ctx->digest);
 365
 366     if (ctx->macctx != NULL) {
 367         /* H(x) = KMAC or H(x) = HMAC */
 368         int ret;
 369         const unsigned char *custom = NULL;
 370         size_t custom_len = 0;
 371         int default_salt_len;
 372         EVP_MAC *mac = EVP_MAC_CTX_mac(ctx->macctx);
 373
 374         if (EVP_MAC_is_a(mac, OSSL_MAC_NAME_HMAC)) {
 375             /* H(x) = HMAC(x, salt, hash) */
 376             if (md == NULL) {
 377                 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 378                 return 0;
 379             }
 380             default_salt_len = EVP_MD_size(md);
 381             if (default_salt_len <= 0)
 382                 return 0;
 383         } else if (EVP_MAC_is_a(mac, OSSL_MAC_NAME_KMAC128)
 384                    || EVP_MAC_is_a(mac, OSSL_MAC_NAME_KMAC256)) {
 385             /* H(x) = KMACzzz(x, salt, custom) */
 386             custom = kmac_custom_str;
 387             custom_len = sizeof(kmac_custom_str);
 388             if (EVP_MAC_is_a(mac, OSSL_MAC_NAME_KMAC128))
 389                 default_salt_len = SSKDF_KMAC128_DEFAULT_SALT_SIZE;
 390             else
 391                 default_salt_len = SSKDF_KMAC256_DEFAULT_SALT_SIZE;
 392         } else {
 393             ERR_raise(ERR_LIB_PROV, PROV_R_UNSUPPORTED_MAC_TYPE);
 394             return 0;
 395         }
 396         /* If no salt is set then use a default_salt of zeros */
 397         if (ctx->salt == NULL || ctx->salt_len <= 0) {
 398             ctx->salt = OPENSSL_zalloc(default_salt_len);
 399             if (ctx->salt == NULL) {
 400                 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
 401                 return 0;
 402             }
 403             ctx->salt_len = default_salt_len;
 404         }
 405         ret = SSKDF_mac_kdm(ctx->macctx,
 406                             custom, custom_len, ctx->out_len,
 407                             ctx->salt, ctx->salt_len,
 408                             ctx->secret, ctx->secret_len,
 409                             ctx->info, ctx->info_len, key, keylen);
 410         return ret;
 411     } else {
 412         /* H(x) = hash */
 413         if (md == NULL) {
 414             ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 415             return 0;
 416         }
 417         return SSKDF_hash_kdm(md, ctx->secret, ctx->secret_len,
 418                               ctx->info, ctx->info_len, 0, key, keylen);
 419     }
 420 }
 421
 422 static int x963kdf_derive(void *vctx, unsigned char *key, size_t keylen)
 423 {
 424     KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
 425     const EVP_MD *md;
 426
 427     if (!ossl_prov_is_running())
 428         return 0;
 429
 430     if (ctx->secret == NULL) {
 431         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
 432         return 0;
 433     }
 434
 435     if (ctx->macctx != NULL) {
 436         ERR_raise(ERR_LIB_PROV, PROV_R_NOT_SUPPORTED);
 437         return 0;
 438     }
 439
 440     /* H(x) = hash */
 441     md = ossl_prov_digest_md(&ctx->digest);
 442     if (md == NULL) {
 443         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 444         return 0;
 445     }
 446
 447     return SSKDF_hash_kdm(md, ctx->secret, ctx->secret_len,
 448                           ctx->info, ctx->info_len, 1, key, keylen);
 449 }
 450
 451 static int sskdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
 452 {
 453     const OSSL_PARAM *p;
 454     KDF_SSKDF *ctx = vctx;
 455     OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
 456     size_t sz;
 457
 458     if (!ossl_prov_digest_load_from_params(&ctx->digest, params, libctx))
 459         return 0;
 460
 461     if (!ossl_prov_macctx_load_from_params(&ctx->macctx, params,
 462                                            NULL, NULL, NULL, libctx))
 463         return 0;
 464
 465     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SECRET)) != NULL
 466         || (p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)
 467         if (!sskdf_set_buffer(&ctx->secret, &ctx->secret_len, p))
 468             return 0;
 469
 470     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_INFO)) != NULL)
 471         if (!sskdf_set_buffer(&ctx->info, &ctx->info_len, p))
 472             return 0;
 473
 474     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SALT)) != NULL)
 475         if (!sskdf_set_buffer(&ctx->salt, &ctx->salt_len, p))
 476             return 0;
 477
 478     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MAC_SIZE))
 479         != NULL) {
 480         if (!OSSL_PARAM_get_size_t(p, &sz) || sz == 0)
 481             return 0;
 482         ctx->out_len = sz;
 483     }
 484     return 1;
 485 }
 486
 487 static const OSSL_PARAM *sskdf_settable_ctx_params(ossl_unused void *provctx)
 488 {
 489     static const OSSL_PARAM known_settable_ctx_params[] = {
 490         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SECRET, NULL, 0),
 491         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
 492         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_INFO, NULL, 0),
 493         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
 494         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
 495         OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MAC, NULL, 0),
 496         OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0),
 497         OSSL_PARAM_size_t(OSSL_KDF_PARAM_MAC_SIZE, NULL),
 498         OSSL_PARAM_END
 499     };
 500     return known_settable_ctx_params;
 501 }
 502
 503 static int sskdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
 504 {
 505     KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
 506     OSSL_PARAM *p;
 507
 508     if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
 509         return OSSL_PARAM_set_size_t(p, sskdf_size(ctx));
 510     return -2;
 511 }
 512
 513 static const OSSL_PARAM *sskdf_gettable_ctx_params(ossl_unused void *provctx)
 514 {
 515     static const OSSL_PARAM known_gettable_ctx_params[] = {
 516         OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
 517         OSSL_PARAM_END
 518     };
 519     return known_gettable_ctx_params;
 520 }
 521
 522 const OSSL_DISPATCH ossl_kdf_sskdf_functions[] = {
 523     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))sskdf_new },
 524     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))sskdf_free },
 525     { OSSL_FUNC_KDF_RESET, (void(*)(void))sskdf_reset },
 526     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))sskdf_derive },
 527     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 528       (void(*)(void))sskdf_settable_ctx_params },
 529     { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))sskdf_set_ctx_params },
 530     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 531       (void(*)(void))sskdf_gettable_ctx_params },
 532     { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))sskdf_get_ctx_params },
 533     { 0, NULL }
 534 };
 535
 536 const OSSL_DISPATCH ossl_kdf_x963_kdf_functions[] = {
 537     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))sskdf_new },
 538     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))sskdf_free },
 539     { OSSL_FUNC_KDF_RESET, (void(*)(void))sskdf_reset },
 540     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))x963kdf_derive },
 541     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 542       (void(*)(void))sskdf_settable_ctx_params },
 543     { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))sskdf_set_ctx_params },
 544     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 545       (void(*)(void))sskdf_gettable_ctx_params },
 546     { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))sskdf_get_ctx_params },
 547     { 0, NULL }
 548 };