providers/common/kdfs/sskdf.c

   1 /*
   2  * Copyright 2019 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 "internal/cryptlib.h"
  46 #include "internal/numbers.h"
  47 #include "internal/evp_int.h"
  48 #include "internal/provider_ctx.h"
  49 #include "internal/providercommonerr.h"
  50 #include "internal/provider_algs.h"
  51
  52 typedef struct {
  53     void *provctx;
  54     EVP_MAC *mac;       /* H(x) = HMAC_hash OR H(x) = KMAC */
  55     EVP_MD *md;         /* H(x) = hash OR when H(x) = HMAC_hash */
  56     unsigned char *secret;
  57     size_t secret_len;
  58     unsigned char *info;
  59     size_t info_len;
  60     unsigned char *salt;
  61     size_t salt_len;
  62     size_t out_len; /* optional KMAC parameter */
  63 } KDF_SSKDF;
  64
  65 #define SSKDF_MAX_INLEN (1<<30)
  66 #define SSKDF_KMAC128_DEFAULT_SALT_SIZE (168 - 4)
  67 #define SSKDF_KMAC256_DEFAULT_SALT_SIZE (136 - 4)
  68
  69 /* KMAC uses a Customisation string of 'KDF' */
  70 static const unsigned char kmac_custom_str[] = { 0x4B, 0x44, 0x46 };
  71
  72 static OSSL_OP_kdf_newctx_fn sskdf_new;
  73 static OSSL_OP_kdf_freectx_fn sskdf_free;
  74 static OSSL_OP_kdf_reset_fn sskdf_reset;
  75 static OSSL_OP_kdf_derive_fn sskdf_derive;
  76 static OSSL_OP_kdf_derive_fn x963kdf_derive;
  77 static OSSL_OP_kdf_settable_ctx_params_fn sskdf_settable_ctx_params;
  78 static OSSL_OP_kdf_set_ctx_params_fn sskdf_set_ctx_params;
  79 static OSSL_OP_kdf_gettable_ctx_params_fn sskdf_gettable_ctx_params;
  80 static OSSL_OP_kdf_get_ctx_params_fn sskdf_get_ctx_params;
  81
  82 /*
  83  * Refer to https://csrc.nist.gov/publications/detail/sp/800-56c/rev-1/final
  84  * Section 4. One-Step Key Derivation using H(x) = hash(x)
  85  * Note: X9.63 also uses this code with the only difference being that the
  86  * counter is appended to the secret 'z'.
  87  * i.e.
  88  *   result[i] = Hash(counter || z || info) for One Step OR
  89  *   result[i] = Hash(z || counter || info) for X9.63.
  90  */
  91 static int SSKDF_hash_kdm(const EVP_MD *kdf_md,
  92                           const unsigned char *z, size_t z_len,
  93                           const unsigned char *info, size_t info_len,
  94                           unsigned int append_ctr,
  95                           unsigned char *derived_key, size_t derived_key_len)
  96 {
  97     int ret = 0, hlen;
  98     size_t counter, out_len, len = derived_key_len;
  99     unsigned char c[4];
 100     unsigned char mac[EVP_MAX_MD_SIZE];
 101     unsigned char *out = derived_key;
 102     EVP_MD_CTX *ctx = NULL, *ctx_init = NULL;
 103
 104     if (z_len > SSKDF_MAX_INLEN || info_len > SSKDF_MAX_INLEN
 105             || derived_key_len > SSKDF_MAX_INLEN
 106             || derived_key_len == 0)
 107         return 0;
 108
 109     hlen = EVP_MD_size(kdf_md);
 110     if (hlen <= 0)
 111         return 0;
 112     out_len = (size_t)hlen;
 113
 114     ctx = EVP_MD_CTX_create();
 115     ctx_init = EVP_MD_CTX_create();
 116     if (ctx == NULL || ctx_init == NULL)
 117         goto end;
 118
 119     if (!EVP_DigestInit(ctx_init, kdf_md))
 120         goto end;
 121
 122     for (counter = 1;; counter++) {
 123         c[0] = (unsigned char)((counter >> 24) & 0xff);
 124         c[1] = (unsigned char)((counter >> 16) & 0xff);
 125         c[2] = (unsigned char)((counter >> 8) & 0xff);
 126         c[3] = (unsigned char)(counter & 0xff);
 127
 128         if (!(EVP_MD_CTX_copy_ex(ctx, ctx_init)
 129                 && (append_ctr || EVP_DigestUpdate(ctx, c, sizeof(c)))
 130                 && EVP_DigestUpdate(ctx, z, z_len)
 131                 && (!append_ctr || EVP_DigestUpdate(ctx, c, sizeof(c)))
 132                 && EVP_DigestUpdate(ctx, info, info_len)))
 133             goto end;
 134         if (len >= out_len) {
 135             if (!EVP_DigestFinal_ex(ctx, out, NULL))
 136                 goto end;
 137             out += out_len;
 138             len -= out_len;
 139             if (len == 0)
 140                 break;
 141         } else {
 142             if (!EVP_DigestFinal_ex(ctx, mac, NULL))
 143                 goto end;
 144             memcpy(out, mac, len);
 145             break;
 146         }
 147     }
 148     ret = 1;
 149 end:
 150     EVP_MD_CTX_destroy(ctx);
 151     EVP_MD_CTX_destroy(ctx_init);
 152     OPENSSL_cleanse(mac, sizeof(mac));
 153     return ret;
 154 }
 155
 156 static int kmac_init(EVP_MAC_CTX *ctx, const unsigned char *custom,
 157                      size_t custom_len, size_t kmac_out_len,
 158                      size_t derived_key_len, unsigned char **out)
 159 {
 160     OSSL_PARAM params[2];
 161
 162     /* Only KMAC has custom data - so return if not KMAC */
 163     if (custom == NULL)
 164         return 1;
 165
 166     params[0] = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_CUSTOM,
 167                                                   (void *)custom, custom_len);
 168     params[1] = OSSL_PARAM_construct_end();
 169
 170     if (!EVP_MAC_CTX_set_params(ctx, params))
 171         return 0;
 172
 173     /* By default only do one iteration if kmac_out_len is not specified */
 174     if (kmac_out_len == 0)
 175         kmac_out_len = derived_key_len;
 176     /* otherwise check the size is valid */
 177     else if (!(kmac_out_len == derived_key_len
 178             || kmac_out_len == 20
 179             || kmac_out_len == 28
 180             || kmac_out_len == 32
 181             || kmac_out_len == 48
 182             || kmac_out_len == 64))
 183         return 0;
 184
 185     params[0] = OSSL_PARAM_construct_size_t(OSSL_MAC_PARAM_SIZE,
 186                                             &kmac_out_len);
 187
 188     if (EVP_MAC_CTX_set_params(ctx, params) <= 0)
 189         return 0;
 190
 191     /*
 192      * For kmac the output buffer can be larger than EVP_MAX_MD_SIZE: so
 193      * alloc a buffer for this case.
 194      */
 195     if (kmac_out_len > EVP_MAX_MD_SIZE) {
 196         *out = OPENSSL_zalloc(kmac_out_len);
 197         if (*out == NULL)
 198             return 0;
 199     }
 200     return 1;
 201 }
 202
 203 /*
 204  * Refer to https://csrc.nist.gov/publications/detail/sp/800-56c/rev-1/final
 205  * Section 4. One-Step Key Derivation using MAC: i.e either
 206  *     H(x) = HMAC-hash(salt, x) OR
 207  *     H(x) = KMAC#(salt, x, outbits, CustomString='KDF')
 208  */
 209 static int SSKDF_mac_kdm(EVP_MAC *kdf_mac, const EVP_MD *hmac_md,
 210                          const unsigned char *kmac_custom,
 211                          size_t kmac_custom_len, size_t kmac_out_len,
 212                          const unsigned char *salt, size_t salt_len,
 213                          const unsigned char *z, size_t z_len,
 214                          const unsigned char *info, size_t info_len,
 215                          unsigned char *derived_key, size_t derived_key_len)
 216 {
 217     int ret = 0;
 218     size_t counter, out_len, len;
 219     unsigned char c[4];
 220     unsigned char mac_buf[EVP_MAX_MD_SIZE];
 221     unsigned char *out = derived_key;
 222     EVP_MAC_CTX *ctx = NULL, *ctx_init = NULL;
 223     unsigned char *mac = mac_buf, *kmac_buffer = NULL;
 224     OSSL_PARAM params[3];
 225     size_t params_n = 0;
 226
 227     if (z_len > SSKDF_MAX_INLEN || info_len > SSKDF_MAX_INLEN
 228             || derived_key_len > SSKDF_MAX_INLEN
 229             || derived_key_len == 0)
 230         return 0;
 231
 232     ctx_init = EVP_MAC_CTX_new(kdf_mac);
 233     if (ctx_init == NULL)
 234         goto end;
 235
 236     if (hmac_md != NULL) {
 237         const char *mdname = EVP_MD_name(hmac_md);
 238         params[params_n++] =
 239             OSSL_PARAM_construct_utf8_string(OSSL_MAC_PARAM_DIGEST,
 240                                              (char *)mdname, 0);
 241     }
 242     params[params_n++] =
 243         OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_KEY, (void *)salt,
 244                                           salt_len);
 245     params[params_n] = OSSL_PARAM_construct_end();
 246
 247     if (!EVP_MAC_CTX_set_params(ctx_init, params))
 248         goto end;
 249
 250     if (!kmac_init(ctx_init, kmac_custom, kmac_custom_len, kmac_out_len,
 251                    derived_key_len, &kmac_buffer))
 252         goto end;
 253     if (kmac_buffer != NULL)
 254         mac = kmac_buffer;
 255
 256     if (!EVP_MAC_init(ctx_init))
 257         goto end;
 258
 259     out_len = EVP_MAC_size(ctx_init); /* output size */
 260     if (out_len <= 0)
 261         goto end;
 262     len = derived_key_len;
 263
 264     for (counter = 1;; counter++) {
 265         c[0] = (unsigned char)((counter >> 24) & 0xff);
 266         c[1] = (unsigned char)((counter >> 16) & 0xff);
 267         c[2] = (unsigned char)((counter >> 8) & 0xff);
 268         c[3] = (unsigned char)(counter & 0xff);
 269
 270         ctx = EVP_MAC_CTX_dup(ctx_init);
 271         if (!(ctx != NULL
 272                 && EVP_MAC_update(ctx, c, sizeof(c))
 273                 && EVP_MAC_update(ctx, z, z_len)
 274                 && EVP_MAC_update(ctx, info, info_len)))
 275             goto end;
 276         if (len >= out_len) {
 277             if (!EVP_MAC_final(ctx, out, NULL, len))
 278                 goto end;
 279             out += out_len;
 280             len -= out_len;
 281             if (len == 0)
 282                 break;
 283         } else {
 284             if (!EVP_MAC_final(ctx, mac, NULL, len))
 285                 goto end;
 286             memcpy(out, mac, len);
 287             break;
 288         }
 289         EVP_MAC_CTX_free(ctx);
 290         ctx = NULL;
 291     }
 292     ret = 1;
 293 end:
 294     if (kmac_buffer != NULL)
 295         OPENSSL_clear_free(kmac_buffer, kmac_out_len);
 296     else
 297         OPENSSL_cleanse(mac_buf, sizeof(mac_buf));
 298
 299     EVP_MAC_CTX_free(ctx);
 300     EVP_MAC_CTX_free(ctx_init);
 301     return ret;
 302 }
 303
 304 static void *sskdf_new(void *provctx)
 305 {
 306     KDF_SSKDF *ctx;
 307
 308     if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
 309         ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
 310     ctx->provctx = provctx;
 311     return ctx;
 312 }
 313
 314 static void sskdf_reset(void *vctx)
 315 {
 316     KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
 317
 318     OPENSSL_clear_free(ctx->secret, ctx->secret_len);
 319     OPENSSL_clear_free(ctx->info, ctx->info_len);
 320     OPENSSL_clear_free(ctx->salt, ctx->salt_len);
 321     EVP_MAC_free(ctx->mac);
 322     memset(ctx, 0, sizeof(*ctx));
 323 }
 324
 325 static void sskdf_free(void *vctx)
 326 {
 327     KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
 328
 329     sskdf_reset(ctx);
 330     EVP_MD_meth_free(ctx->md);
 331     EVP_MAC_free(ctx->mac);
 332     OPENSSL_free(ctx);
 333 }
 334
 335 static int sskdf_set_buffer(unsigned char **out, size_t *out_len,
 336                             const OSSL_PARAM *p)
 337 {
 338     if (p->data == NULL || p->data_size == 0)
 339         return 1;
 340     OPENSSL_free(*out);
 341     *out = NULL;
 342     return OSSL_PARAM_get_octet_string(p, (void **)out, 0, out_len);
 343 }
 344
 345 static size_t sskdf_size(KDF_SSKDF *ctx)
 346 {
 347     int len;
 348
 349     if (ctx->md == NULL) {
 350         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 351         return 0;
 352     }
 353     len = EVP_MD_size(ctx->md);
 354     return (len <= 0) ? 0 : (size_t)len;
 355 }
 356
 357 static int sskdf_derive(void *vctx, unsigned char *key, size_t keylen)
 358 {
 359     KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
 360
 361     if (ctx->secret == NULL) {
 362         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
 363         return 0;
 364     }
 365
 366     if (ctx->mac != 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         const char *macname;
 372         int default_salt_len;
 373
 374         /*
 375          * TODO(3.0) investigate the necessity to have all these controls.
 376          * Why does KMAC require a salt length that's shorter than the MD
 377          * block size?
 378          */
 379         macname = EVP_MAC_name(ctx->mac);
 380         if (strcmp(macname, OSSL_MAC_NAME_HMAC) == 0) {
 381             /* H(x) = HMAC(x, salt, hash) */
 382             if (ctx->md == NULL) {
 383                 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 384                 return 0;
 385             }
 386             default_salt_len = EVP_MD_block_size(ctx->md);
 387             if (default_salt_len <= 0)
 388                 return 0;
 389         } else if (strcmp(macname, OSSL_MAC_NAME_KMAC128) == 0
 390                    || strcmp(macname, OSSL_MAC_NAME_KMAC256) == 0) {
 391             /* H(x) = KMACzzz(x, salt, custom) */
 392             custom = kmac_custom_str;
 393             custom_len = sizeof(kmac_custom_str);
 394             if (strcmp(macname, OSSL_MAC_NAME_KMAC128) == 0)
 395                 default_salt_len = SSKDF_KMAC128_DEFAULT_SALT_SIZE;
 396             else
 397                 default_salt_len = SSKDF_KMAC256_DEFAULT_SALT_SIZE;
 398         } else {
 399             ERR_raise(ERR_LIB_PROV, PROV_R_UNSUPPORTED_MAC_TYPE);
 400             return 0;
 401         }
 402         /* If no salt is set then use a default_salt of zeros */
 403         if (ctx->salt == NULL || ctx->salt_len <= 0) {
 404             ctx->salt = OPENSSL_zalloc(default_salt_len);
 405             if (ctx->salt == NULL) {
 406                 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
 407                 return 0;
 408             }
 409             ctx->salt_len = default_salt_len;
 410         }
 411         ret = SSKDF_mac_kdm(ctx->mac, ctx->md,
 412                             custom, custom_len, ctx->out_len,
 413                             ctx->salt, ctx->salt_len,
 414                             ctx->secret, ctx->secret_len,
 415                             ctx->info, ctx->info_len, key, keylen);
 416         return ret;
 417     } else {
 418         /* H(x) = hash */
 419         if (ctx->md == NULL) {
 420             ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 421             return 0;
 422         }
 423         return SSKDF_hash_kdm(ctx->md, ctx->secret, ctx->secret_len,
 424                               ctx->info, ctx->info_len, 0, key, keylen);
 425     }
 426 }
 427
 428 static int x963kdf_derive(void *vctx, unsigned char *key, size_t keylen)
 429 {
 430     KDF_SSKDF *ctx = (KDF_SSKDF *)vctx;
 431
 432     if (ctx->secret == NULL) {
 433         ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
 434         return 0;
 435     }
 436
 437     if (ctx->mac != NULL) {
 438         ERR_raise(ERR_LIB_PROV, PROV_R_NOT_SUPPORTED);
 439         return 0;
 440     } else {
 441         /* H(x) = hash */
 442         if (ctx->md == NULL) {
 443             ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
 444             return 0;
 445         }
 446         return SSKDF_hash_kdm(ctx->md, ctx->secret, ctx->secret_len,
 447                               ctx->info, ctx->info_len, 1, key, keylen);
 448     }
 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     EVP_MD *md;
 456     EVP_MAC *mac;
 457     size_t sz;
 458     const char *properties = NULL;
 459
 460     /* Grab search properties, should be before the digest and mac lookups */
 461     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_PROPERTIES))
 462         != NULL) {
 463         if (p->data_type != OSSL_PARAM_UTF8_STRING)
 464             return 0;
 465         properties = p->data;
 466     }
 467     /* Handle aliasing of digest parameter names */
 468     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_DIGEST)) != NULL) {
 469         if (p->data_type != OSSL_PARAM_UTF8_STRING)
 470             return 0;
 471         md = EVP_MD_fetch(PROV_LIBRARY_CONTEXT_OF(ctx->provctx), p->data,
 472                           properties);
 473         if (md == NULL) {
 474             ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_DIGEST);
 475             return 0;
 476         }
 477         EVP_MD_meth_free(ctx->md);
 478         ctx->md = md;
 479     }
 480
 481     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MAC)) != NULL) {
 482         EVP_MAC_free(ctx->mac);
 483         ctx->mac = NULL;
 484
 485         mac = EVP_MAC_fetch(PROV_LIBRARY_CONTEXT_OF(ctx->provctx), p->data,
 486                             properties);
 487         if (mac == NULL)
 488             return 0;
 489         EVP_MAC_free(ctx->mac);
 490         ctx->mac = mac;
 491     }
 492
 493     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SECRET)) != NULL
 494         || (p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)
 495         if (!sskdf_set_buffer(&ctx->secret, &ctx->secret_len, p))
 496             return 0;
 497
 498     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_INFO)) != NULL)
 499         if (!sskdf_set_buffer(&ctx->info, &ctx->info_len, p))
 500             return 0;
 501
 502     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SALT)) != NULL)
 503         if (!sskdf_set_buffer(&ctx->salt, &ctx->salt_len, p))
 504             return 0;
 505
 506     if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MAC_SIZE))
 507         != NULL) {
 508         if (!OSSL_PARAM_get_size_t(p, &sz) || sz == 0)
 509             return 0;
 510         ctx->out_len = sz;
 511     }
 512     return 1;
 513 }
 514
 515 static const OSSL_PARAM *sskdf_settable_ctx_params(void)
 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(void)
 542 {
 543     static const OSSL_PARAM known_gettable_ctx_params[] = {
 544         OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
 545         OSSL_PARAM_END
 546     };
 547     return known_gettable_ctx_params;
 548 }
 549
 550 const OSSL_DISPATCH kdf_sskdf_functions[] = {
 551     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))sskdf_new },
 552     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))sskdf_free },
 553     { OSSL_FUNC_KDF_RESET, (void(*)(void))sskdf_reset },
 554     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))sskdf_derive },
 555     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 556       (void(*)(void))sskdf_settable_ctx_params },
 557     { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))sskdf_set_ctx_params },
 558     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 559       (void(*)(void))sskdf_gettable_ctx_params },
 560     { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))sskdf_get_ctx_params },
 561     { 0, NULL }
 562 };
 563
 564 const OSSL_DISPATCH kdf_x963_kdf_functions[] = {
 565     { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))sskdf_new },
 566     { OSSL_FUNC_KDF_FREECTX, (void(*)(void))sskdf_free },
 567     { OSSL_FUNC_KDF_RESET, (void(*)(void))sskdf_reset },
 568     { OSSL_FUNC_KDF_DERIVE, (void(*)(void))x963kdf_derive },
 569     { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
 570       (void(*)(void))sskdf_settable_ctx_params },
 571     { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))sskdf_set_ctx_params },
 572     { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
 573       (void(*)(void))sskdf_gettable_ctx_params },
 574     { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))sskdf_get_ctx_params },
 575     { 0, NULL }
 576 };