providers/implementations/macs/kmac_prov.c

   1 /*
   2  * Copyright 2018-2021 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 /*
  11  * See SP800-185 "Appendix A - KMAC, .... in Terms of Keccak[c]"
  12  *
  13  * Inputs are:
  14  *    K = Key                  (len(K) < 2^2040 bits)
  15  *    X = Input
  16  *    L = Output length        (0 <= L < 2^2040 bits)
  17  *    S = Customization String Default="" (len(S) < 2^2040 bits)
  18  *
  19  * KMAC128(K, X, L, S)
  20  * {
  21  *     newX = bytepad(encode_string(K), 168) ||  X || right_encode(L).
  22  *     T = bytepad(encode_string("KMAC") || encode_string(S), 168).
  23  *     return KECCAK[256](T || newX || 00, L).
  24  * }
  25  *
  26  * KMAC256(K, X, L, S)
  27  * {
  28  *     newX = bytepad(encode_string(K), 136) ||  X || right_encode(L).
  29  *     T = bytepad(encode_string("KMAC") || encode_string(S), 136).
  30  *     return KECCAK[512](T || newX || 00, L).
  31  * }
  32  *
  33  * KMAC128XOF(K, X, L, S)
  34  * {
  35  *     newX = bytepad(encode_string(K), 168) ||  X || right_encode(0).
  36  *     T = bytepad(encode_string("KMAC") || encode_string(S), 168).
  37  *     return KECCAK[256](T || newX || 00, L).
  38  * }
  39  *
  40  * KMAC256XOF(K, X, L, S)
  41  * {
  42  *     newX = bytepad(encode_string(K), 136) ||  X || right_encode(0).
  43  *     T = bytepad(encode_string("KMAC") || encode_string(S), 136).
  44  *     return KECCAK[512](T || newX || 00, L).
  45  * }
  46  *
  47  */
  48
  49 #include <stdlib.h>
  50 #include <string.h>
  51 #include <openssl/core_dispatch.h>
  52 #include <openssl/core_names.h>
  53 #include <openssl/params.h>
  54 #include <openssl/evp.h>
  55 #include <openssl/err.h>
  56 #include <openssl/proverr.h>
  57
  58 #include "prov/implementations.h"
  59 #include "prov/provider_ctx.h"
  60 #include "prov/provider_util.h"
  61 #include "prov/providercommon.h"
  62
  63 /*
  64  * Forward declaration of everything implemented here.  This is not strictly
  65  * necessary for the compiler, but provides an assurance that the signatures
  66  * of the functions in the dispatch table are correct.
  67  */
  68 static OSSL_FUNC_mac_newctx_fn kmac128_new;
  69 static OSSL_FUNC_mac_newctx_fn kmac256_new;
  70 static OSSL_FUNC_mac_dupctx_fn kmac_dup;
  71 static OSSL_FUNC_mac_freectx_fn kmac_free;
  72 static OSSL_FUNC_mac_gettable_ctx_params_fn kmac_gettable_ctx_params;
  73 static OSSL_FUNC_mac_get_ctx_params_fn kmac_get_ctx_params;
  74 static OSSL_FUNC_mac_settable_ctx_params_fn kmac_settable_ctx_params;
  75 static OSSL_FUNC_mac_set_ctx_params_fn kmac_set_ctx_params;
  76 static OSSL_FUNC_mac_init_fn kmac_init;
  77 static OSSL_FUNC_mac_update_fn kmac_update;
  78 static OSSL_FUNC_mac_final_fn kmac_final;
  79
  80 #define KMAC_MAX_BLOCKSIZE ((1600 - 128*2) / 8) /* 168 */
  81 #define KMAC_MIN_BLOCKSIZE ((1600 - 256*2) / 8) /* 136 */
  82
  83 /* Length encoding will be  a 1 byte size + length in bits (2 bytes max) */
  84 #define KMAC_MAX_ENCODED_HEADER_LEN 3
  85
  86 /*
  87  * Custom string max size is chosen such that:
  88  *   len(encoded_string(custom) + len(kmac_encoded_string) <= KMAC_MIN_BLOCKSIZE
  89  *   i.e: (KMAC_MAX_CUSTOM + KMAC_MAX_ENCODED_LEN) + 6 <= 136
  90  */
  91 #define KMAC_MAX_CUSTOM 127
  92
  93 /* Maximum size of encoded custom string */
  94 #define KMAC_MAX_CUSTOM_ENCODED (KMAC_MAX_CUSTOM + KMAC_MAX_ENCODED_HEADER_LEN)
  95
  96 /* Maximum key size in bytes = 2040 / 8 */
  97 #define KMAC_MAX_KEY 255
  98
  99 /*
 100  * Maximum Encoded Key size will be padded to a multiple of the blocksize
 101  * i.e KMAC_MAX_KEY + KMAC_MAX_ENCODED_LEN = 258
 102  * Padded to a multiple of KMAC_MAX_BLOCKSIZE
 103  */
 104 #define KMAC_MAX_KEY_ENCODED (KMAC_MAX_BLOCKSIZE * 2)
 105
 106 /* Fixed value of encode_string("KMAC") */
 107 static const unsigned char kmac_string[] = {
 108     0x01, 0x20, 0x4B, 0x4D, 0x41, 0x43
 109 };
 110
 111
 112 #define KMAC_FLAG_XOF_MODE          1
 113
 114 struct kmac_data_st {
 115     void  *provctx;
 116     EVP_MD_CTX *ctx;
 117     PROV_DIGEST digest;
 118     size_t out_len;
 119     int key_len;
 120     int custom_len;
 121     /* If xof_mode = 1 then we use right_encode(0) */
 122     int xof_mode;
 123     /* key and custom are stored in encoded form */
 124     unsigned char key[KMAC_MAX_KEY_ENCODED];
 125     unsigned char custom[KMAC_MAX_CUSTOM_ENCODED];
 126 };
 127
 128 static int encode_string(unsigned char *out, int *out_len,
 129                          const unsigned char *in, int in_len);
 130 static int right_encode(unsigned char *out, int *out_len, size_t bits);
 131 static int bytepad(unsigned char *out, int *out_len,
 132                    const unsigned char *in1, int in1_len,
 133                    const unsigned char *in2, int in2_len,
 134                    int w);
 135 static int kmac_bytepad_encode_key(unsigned char *out, int *out_len,
 136                                    const unsigned char *in, int in_len,
 137                                    int w);
 138
 139 static void kmac_free(void *vmacctx)
 140 {
 141     struct kmac_data_st *kctx = vmacctx;
 142
 143     if (kctx != NULL) {
 144         EVP_MD_CTX_free(kctx->ctx);
 145         ossl_prov_digest_reset(&kctx->digest);
 146         OPENSSL_cleanse(kctx->key, kctx->key_len);
 147         OPENSSL_cleanse(kctx->custom, kctx->custom_len);
 148         OPENSSL_free(kctx);
 149     }
 150 }
 151
 152 /*
 153  * We have KMAC implemented as a hash, which we can use instead of
 154  * reimplementing the EVP functionality with direct use of
 155  * keccak_mac_init() and friends.
 156  */
 157 static struct kmac_data_st *kmac_new(void *provctx)
 158 {
 159     struct kmac_data_st *kctx;
 160
 161     if (!ossl_prov_is_running())
 162         return NULL;
 163
 164     if ((kctx = OPENSSL_zalloc(sizeof(*kctx))) == NULL
 165             || (kctx->ctx = EVP_MD_CTX_new()) == NULL) {
 166         kmac_free(kctx);
 167         return NULL;
 168     }
 169     kctx->provctx = provctx;
 170     return kctx;
 171 }
 172
 173 static void *kmac_fetch_new(void *provctx, const OSSL_PARAM *params)
 174 {
 175     struct kmac_data_st *kctx = kmac_new(provctx);
 176
 177     if (kctx == NULL)
 178         return 0;
 179     if (!ossl_prov_digest_load_from_params(&kctx->digest, params,
 180                                       PROV_LIBCTX_OF(provctx))) {
 181         kmac_free(kctx);
 182         return 0;
 183     }
 184
 185     kctx->out_len = EVP_MD_size(ossl_prov_digest_md(&kctx->digest));
 186     return kctx;
 187 }
 188
 189 static void *kmac128_new(void *provctx)
 190 {
 191     static const OSSL_PARAM kmac128_params[] = {
 192         OSSL_PARAM_utf8_string("digest", OSSL_DIGEST_NAME_KECCAK_KMAC128,
 193                                sizeof(OSSL_DIGEST_NAME_KECCAK_KMAC128)),
 194         OSSL_PARAM_END
 195     };
 196     return kmac_fetch_new(provctx, kmac128_params);
 197 }
 198
 199 static void *kmac256_new(void *provctx)
 200 {
 201     static const OSSL_PARAM kmac256_params[] = {
 202         OSSL_PARAM_utf8_string("digest", OSSL_DIGEST_NAME_KECCAK_KMAC256,
 203                                sizeof(OSSL_DIGEST_NAME_KECCAK_KMAC256)),
 204         OSSL_PARAM_END
 205     };
 206     return kmac_fetch_new(provctx, kmac256_params);
 207 }
 208
 209 static void *kmac_dup(void *vsrc)
 210 {
 211     struct kmac_data_st *src = vsrc;
 212     struct kmac_data_st *dst;
 213
 214     if (!ossl_prov_is_running())
 215         return NULL;
 216
 217     dst = kmac_new(src->provctx);
 218     if (dst == NULL)
 219         return NULL;
 220
 221     if (!EVP_MD_CTX_copy(dst->ctx, src->ctx)
 222         || !ossl_prov_digest_copy(&dst->digest, &src->digest)) {
 223         kmac_free(dst);
 224         return NULL;
 225     }
 226
 227     dst->out_len = src->out_len;
 228     dst->key_len = src->key_len;
 229     dst->custom_len = src->custom_len;
 230     dst->xof_mode = src->xof_mode;
 231     memcpy(dst->key, src->key, src->key_len);
 232     memcpy(dst->custom, src->custom, dst->custom_len);
 233
 234     return dst;
 235 }
 236
 237 static size_t kmac_size(void *vmacctx)
 238 {
 239     struct kmac_data_st *kctx = vmacctx;
 240
 241     return kctx->out_len;
 242 }
 243
 244 /*
 245  * The init() assumes that any ctrl methods are set beforehand for
 246  * md, key and custom. Setting the fields afterwards will have no
 247  * effect on the output mac.
 248  */
 249 static int kmac_init(void *vmacctx)
 250 {
 251     struct kmac_data_st *kctx = vmacctx;
 252     EVP_MD_CTX *ctx = kctx->ctx;
 253     unsigned char out[KMAC_MAX_BLOCKSIZE];
 254     int out_len, block_len;
 255
 256     if (!ossl_prov_is_running())
 257         return 0;
 258
 259     /* Check key has been set */
 260     if (kctx->key_len == 0) {
 261         ERR_raise(ERR_LIB_PROV, PROV_R_NO_KEY_SET);
 262         return 0;
 263     }
 264     if (!EVP_DigestInit_ex(kctx->ctx, ossl_prov_digest_md(&kctx->digest),
 265                            NULL))
 266         return 0;
 267
 268     block_len = EVP_MD_block_size(ossl_prov_digest_md(&kctx->digest));
 269     if (block_len < 0)
 270         return 0;
 271
 272     /* Set default custom string if it is not already set */
 273     if (kctx->custom_len == 0) {
 274         const OSSL_PARAM params[] = {
 275             OSSL_PARAM_octet_string(OSSL_MAC_PARAM_CUSTOM, "", 0),
 276             OSSL_PARAM_END
 277         };
 278         (void)kmac_set_ctx_params(kctx, params);
 279     }
 280
 281     return bytepad(out, &out_len, kmac_string, sizeof(kmac_string),
 282                    kctx->custom, kctx->custom_len, block_len)
 283            && EVP_DigestUpdate(ctx, out, out_len)
 284            && EVP_DigestUpdate(ctx, kctx->key, kctx->key_len);
 285 }
 286
 287 static int kmac_update(void *vmacctx, const unsigned char *data,
 288                        size_t datalen)
 289 {
 290     struct kmac_data_st *kctx = vmacctx;
 291
 292     return EVP_DigestUpdate(kctx->ctx, data, datalen);
 293 }
 294
 295 static int kmac_final(void *vmacctx, unsigned char *out, size_t *outl,
 296                       size_t outsize)
 297 {
 298     struct kmac_data_st *kctx = vmacctx;
 299     EVP_MD_CTX *ctx = kctx->ctx;
 300     int lbits, len;
 301     unsigned char encoded_outlen[KMAC_MAX_ENCODED_HEADER_LEN];
 302     int ok;
 303
 304     if (!ossl_prov_is_running())
 305         return 0;
 306
 307     /* KMAC XOF mode sets the encoded length to 0 */
 308     lbits = (kctx->xof_mode ? 0 : (kctx->out_len * 8));
 309
 310     ok = right_encode(encoded_outlen, &len, lbits)
 311         && EVP_DigestUpdate(ctx, encoded_outlen, len)
 312         && EVP_DigestFinalXOF(ctx, out, kctx->out_len);
 313     *outl = kctx->out_len;
 314     return ok;
 315 }
 316
 317 static const OSSL_PARAM known_gettable_ctx_params[] = {
 318     OSSL_PARAM_size_t(OSSL_MAC_PARAM_SIZE, NULL),
 319     OSSL_PARAM_END
 320 };
 321 static const OSSL_PARAM *kmac_gettable_ctx_params(ossl_unused void *provctx)
 322 {
 323     return known_gettable_ctx_params;
 324 }
 325
 326 static int kmac_get_ctx_params(void *vmacctx, OSSL_PARAM params[])
 327 {
 328     OSSL_PARAM *p;
 329
 330     if ((p = OSSL_PARAM_locate(params, OSSL_MAC_PARAM_SIZE)) != NULL)
 331         return OSSL_PARAM_set_size_t(p, kmac_size(vmacctx));
 332
 333     return 1;
 334 }
 335
 336 static const OSSL_PARAM known_settable_ctx_params[] = {
 337     OSSL_PARAM_int(OSSL_MAC_PARAM_XOF, NULL),
 338     OSSL_PARAM_size_t(OSSL_MAC_PARAM_SIZE, NULL),
 339     OSSL_PARAM_octet_string(OSSL_MAC_PARAM_KEY, NULL, 0),
 340     OSSL_PARAM_octet_string(OSSL_MAC_PARAM_CUSTOM, NULL, 0),
 341     OSSL_PARAM_END
 342 };
 343 static const OSSL_PARAM *kmac_settable_ctx_params(ossl_unused void *provctx)
 344 {
 345     return known_settable_ctx_params;
 346 }
 347
 348 /*
 349  * The following params can be set any time before final():
 350  *     - "outlen" or "size":    The requested output length.
 351  *     - "xof":                 If set, this indicates that right_encoded(0)
 352  *                              is part of the digested data, otherwise it
 353  *                              uses right_encoded(requested output length).
 354  *
 355  * All other params should be set before init().
 356  */
 357 static int kmac_set_ctx_params(void *vmacctx, const OSSL_PARAM *params)
 358 {
 359     struct kmac_data_st *kctx = vmacctx;
 360     const OSSL_PARAM *p;
 361     const EVP_MD *digest = ossl_prov_digest_md(&kctx->digest);
 362
 363     if ((p = OSSL_PARAM_locate_const(params, OSSL_MAC_PARAM_XOF)) != NULL
 364         && !OSSL_PARAM_get_int(p, &kctx->xof_mode))
 365         return 0;
 366     if (((p = OSSL_PARAM_locate_const(params, OSSL_MAC_PARAM_SIZE)) != NULL)
 367         && !OSSL_PARAM_get_size_t(p, &kctx->out_len))
 368         return 0;
 369     if ((p = OSSL_PARAM_locate_const(params, OSSL_MAC_PARAM_KEY)) != NULL) {
 370         if (p->data_size < 4 || p->data_size > KMAC_MAX_KEY) {
 371             ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
 372             return 0;
 373         }
 374         if (!kmac_bytepad_encode_key(kctx->key, &kctx->key_len,
 375                                      p->data, p->data_size,
 376                                      EVP_MD_block_size(digest)))
 377             return 0;
 378     }
 379     if ((p = OSSL_PARAM_locate_const(params, OSSL_MAC_PARAM_CUSTOM))
 380         != NULL) {
 381         if (p->data_size > KMAC_MAX_CUSTOM) {
 382             ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_CUSTOM_LENGTH);
 383             return 0;
 384         }
 385         if (!encode_string(kctx->custom, &kctx->custom_len,
 386                            p->data, p->data_size))
 387             return 0;
 388     }
 389     return 1;
 390 }
 391
 392 /*
 393  * Encoding/Padding Methods.
 394  */
 395
 396 /* Returns the number of bytes required to store 'bits' into a byte array */
 397 static unsigned int get_encode_size(size_t bits)
 398 {
 399     unsigned int cnt = 0, sz = sizeof(size_t);
 400
 401     while (bits && (cnt < sz)) {
 402         ++cnt;
 403         bits >>= 8;
 404     }
 405     /* If bits is zero 1 byte is required */
 406     if (cnt == 0)
 407         cnt = 1;
 408     return cnt;
 409 }
 410
 411 /*
 412  * Convert an integer into bytes . The number of bytes is appended
 413  * to the end of the buffer. Returns an array of bytes 'out' of size
 414  * *out_len.
 415  *
 416  * e.g if bits = 32, out[2] = { 0x20, 0x01 }
 417  *
 418  */
 419 static int right_encode(unsigned char *out, int *out_len, size_t bits)
 420 {
 421     unsigned int len = get_encode_size(bits);
 422     int i;
 423
 424     /* The length is constrained to a single byte: 2040/8 = 255 */
 425     if (len > 0xFF)
 426         return 0;
 427
 428     /* MSB's are at the start of the bytes array */
 429     for (i = len - 1; i >= 0; --i) {
 430         out[i] = (unsigned char)(bits & 0xFF);
 431         bits >>= 8;
 432     }
 433     /* Tack the length onto the end */
 434     out[len] = (unsigned char)len;
 435
 436     /* The Returned length includes the tacked on byte */
 437     *out_len = len + 1;
 438     return 1;
 439 }
 440
 441 /*
 442  * Encodes a string with a left encoded length added. Note that the
 443  * in_len is converted to bits (*8).
 444  *
 445  * e.g- in="KMAC" gives out[6] = { 0x01, 0x20, 0x4B, 0x4D, 0x41, 0x43 }
 446  *                                 len   bits    K     M     A     C
 447  */
 448 static int encode_string(unsigned char *out, int *out_len,
 449                          const unsigned char *in, int in_len)
 450 {
 451     if (in == NULL) {
 452         *out_len = 0;
 453     } else {
 454         int i, bits, len;
 455
 456         bits = 8 * in_len;
 457         len = get_encode_size(bits);
 458         if (len > 0xFF)
 459             return 0;
 460
 461         out[0] = len;
 462         for (i = len; i > 0; --i) {
 463             out[i] = (bits & 0xFF);
 464             bits >>= 8;
 465         }
 466         memcpy(out + len + 1, in, in_len);
 467         *out_len = (1 + len + in_len);
 468     }
 469     return 1;
 470 }
 471
 472 /*
 473  * Returns a zero padded encoding of the inputs in1 and an optional
 474  * in2 (can be NULL). The padded output must be a multiple of the blocksize 'w'.
 475  * The value of w is in bytes (< 256).
 476  *
 477  * The returned output is:
 478  *    zero_padded(multiple of w, (left_encode(w) || in1 [|| in2])
 479  */
 480 static int bytepad(unsigned char *out, int *out_len,
 481                    const unsigned char *in1, int in1_len,
 482                    const unsigned char *in2, int in2_len, int w)
 483 {
 484     int len;
 485     unsigned char *p = out;
 486     int sz = w;
 487
 488     /* Left encoded w */
 489     *p++ = 1;
 490     *p++ = w;
 491     /* || in1 */
 492     memcpy(p, in1, in1_len);
 493     p += in1_len;
 494     /* [ || in2 ] */
 495     if (in2 != NULL && in2_len > 0) {
 496         memcpy(p, in2, in2_len);
 497         p += in2_len;
 498     }
 499     /* Figure out the pad size (divisible by w) */
 500     len = p - out;
 501     while (len > sz) {
 502         sz += w;
 503     }
 504     /* zero pad the end of the buffer */
 505     memset(p, 0, sz - len);
 506     *out_len = sz;
 507     return 1;
 508 }
 509
 510 /*
 511  * Returns out = bytepad(encode_string(in), w)
 512  */
 513 static int kmac_bytepad_encode_key(unsigned char *out, int *out_len,
 514                                    const unsigned char *in, int in_len,
 515                                    int w)
 516 {
 517     unsigned char tmp[KMAC_MAX_KEY + KMAC_MAX_ENCODED_HEADER_LEN];
 518     int tmp_len;
 519
 520     if (!encode_string(tmp, &tmp_len, in, in_len))
 521         return 0;
 522
 523     return bytepad(out, out_len, tmp, tmp_len, NULL, 0, w);
 524 }
 525
 526 const OSSL_DISPATCH ossl_kmac128_functions[] = {
 527     { OSSL_FUNC_MAC_NEWCTX, (void (*)(void))kmac128_new },
 528     { OSSL_FUNC_MAC_DUPCTX, (void (*)(void))kmac_dup },
 529     { OSSL_FUNC_MAC_FREECTX, (void (*)(void))kmac_free },
 530     { OSSL_FUNC_MAC_INIT, (void (*)(void))kmac_init },
 531     { OSSL_FUNC_MAC_UPDATE, (void (*)(void))kmac_update },
 532     { OSSL_FUNC_MAC_FINAL, (void (*)(void))kmac_final },
 533     { OSSL_FUNC_MAC_GETTABLE_CTX_PARAMS,
 534       (void (*)(void))kmac_gettable_ctx_params },
 535     { OSSL_FUNC_MAC_GET_CTX_PARAMS, (void (*)(void))kmac_get_ctx_params },
 536     { OSSL_FUNC_MAC_SETTABLE_CTX_PARAMS,
 537       (void (*)(void))kmac_settable_ctx_params },
 538     { OSSL_FUNC_MAC_SET_CTX_PARAMS, (void (*)(void))kmac_set_ctx_params },
 539     { 0, NULL }
 540 };
 541
 542 const OSSL_DISPATCH ossl_kmac256_functions[] = {
 543     { OSSL_FUNC_MAC_NEWCTX, (void (*)(void))kmac256_new },
 544     { OSSL_FUNC_MAC_DUPCTX, (void (*)(void))kmac_dup },
 545     { OSSL_FUNC_MAC_FREECTX, (void (*)(void))kmac_free },
 546     { OSSL_FUNC_MAC_INIT, (void (*)(void))kmac_init },
 547     { OSSL_FUNC_MAC_UPDATE, (void (*)(void))kmac_update },
 548     { OSSL_FUNC_MAC_FINAL, (void (*)(void))kmac_final },
 549     { OSSL_FUNC_MAC_GETTABLE_CTX_PARAMS,
 550       (void (*)(void))kmac_gettable_ctx_params },
 551     { OSSL_FUNC_MAC_GET_CTX_PARAMS, (void (*)(void))kmac_get_ctx_params },
 552     { OSSL_FUNC_MAC_SETTABLE_CTX_PARAMS,
 553       (void (*)(void))kmac_settable_ctx_params },
 554     { OSSL_FUNC_MAC_SET_CTX_PARAMS, (void (*)(void))kmac_set_ctx_params },
 555     { 0, NULL }
 556 };